itu-r working party 8b activities - international civil · web viewa block diagram of the type...

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AMCP-WG F WP/2

Aeronautical Mobile Communications PanelWorking Group F

(Lima, 27 March – 4 April 2001)

Agenda Item 2: Review of outcome of ITU Working Parties and Task Groups (8B, 8D, 8F & 1/5)

ITU-R Working Party 8B activities(Presented by the Secretary)

The present paper contains information on ITU-R Working party 8B activities that may be of interest to AMCP WGF, in particular with regard to WRC-2003 preparation. Sources of the information are indicated in the body of the paper as applicable. They include:

- WP8B meeting report Geneva (10-18 October 2000);- SG8 working papers produced by WP8B;- liaison statements from WP8B to other groups; and- WP8B document.

The document is in ten parts. ICAO Secretariat comments and proposed action by AMCP WGF are provided for each part.

Part 1 (p.3): Reply from WP8B to liaison statements of Task Group 1/5 on out-of-band emissions of primary radars and protection of safety services from unwanted emissions (ITU-R Document 1-5/64-E)

Part 2 (p.45) Draft revision of Recommendation ITU-R M.589.2 on the "Technical characteristics of methods of data transmission and interference protection for radionavigation services in the frequency bands between 70 and 130 kHz" (ITU-R Document 8/14).

Part 3 (p.64) Preparations for WRC-03 (Attachment 11 to ITU-R Document 8B/49-E - Report of the eighth meeting of Working Party 8B)

Part 4 (p.78) Liaison statement to WP 1A on a "Study of interference from short-range radio devices using ultra wideband (UWB) technology operating in the 1 - 6 GHz bands (ITU-R Document 1A/28-E).

Part 5 (p.82) Draft revision to question ITU-R 216-1/8 on the "Compatibility of radionavigation, Earth exploration-satellite (active), Space research (active) and radiolocation services operating in the 5350 - 5650 MHz and 2900 - 3100 MHz band." (ITU-R Document SG8/16)

/TT/FILE_CONVERT/5AB825E17F8B9AC1058C587D/DOCUMENT.DOC 06/05/2023 06/05/2023

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Part 6 (p.85) Preliminary draft new recommendation ITU-R M. – Characteristics of and protection criteria for radiolocation aeronautical radionaviafation and meteorological radars operating in the frequency bands between 5 250 and 5 850 MHz (ITU-R Document 7C/42-E)

Part 7 (p.98) Revised work plan for working party 8B for completing urgent studies under question ITU-R 216/8 (Attachment 5 to ITU-R Document 8B/49-E - Report of the eighth meeting of Working Party 8B)

Part 8 (p.112) Liaison statements to working party 8F on interference from IMT-2000 and other services (including the radiodetermination service) (ITU-R Document 8F/169-E)

Part 9 (p.121) Response to liaison statement from working party 7C on the "sharing between the Earth exploration-satellite service (passive) and the ARNS in the band 4200 - 4400 MHz (ITU-R Document 7C/53E).

Part 10 (p.125) Liaison statement to working party 8D concerning the protection of radar in the band 1215 - 1300 MHz (ITU-R Document 8D/49-E).


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Part 1Reply from WP8B to liaison statements of Task Group 1/5 on out-of-band emissions of primary radars and protection of safety services from unwanted emissions (ITU-R Document 1-5/64-E)

ICAO Secretariat comments:

This ITU-R TG1/5 document is based on Documents 8B/TEMP/1, 10, 11 and 12, produced by the October 2000 meeting of WP8B. It contains various comments from WP8B on liaison statements from Task Group 1/5 on the out-of-band emissions and protection of radar.

1. Attachment 1 to Doc 1-5/64-E provides two techniques for the measurement of unwanted emissions of radar systems that should be used to assess compliance with Appendix S3 (Section II) of the radio regulations.

AMCP WGF ACTION: Review these proposals

2. Attachment 2 to Doc 1-5/64-E contains comments from WP8B to TG 1/5 concerning a preliminary draft new recommendation on the "Protection of safety services from unwanted emissions" . This important draft new recommendation proposes various guidelines to be observed when protecting (aeronautical) safety services from interference from unwanted emissions. The output from TG 1/5 is awaited with a view to secure adequate treatment of the aviation's requirements for the protection of aeronautical services.

AMCP WGF ACTION: Review the PDNR

3. Attachment 3 to Doc 1-5/64-E contains a draft revision of Question ITU-R 202-1/8 ("Unwanted emissions of primary radar systems"). This revision intends to include in the studies of unwanted emissions of primary radar systems references to Recommendation ITU-R F.1097 and ITU-R F.1190 on mitigation option to enhance compatibility between radar and digital radio relay systems and protection criteria for digital radio relay systems to ensure compatibility with radar. Also references to the revised (at WRC 2000) appendix S3 of the Radio Regulations (Table of maximum spurious emission power levels) and Recommendation ITU-R SM.329 are included as well as references to Recommendations ITU-R M.1177 and M.1314 on the techniques for measurement of unwanted emissions from radar systems and the reduction of spurious emission of radar systems are incorporated. The goal is to determine the unwanted emission levels from existing state-of-the-art radar systems and the levels of unwanted emission that can be achieved using various mitigation options. As a result of the widening of the scope of the study question, it is necessary to ensure that mitigation options that might be considered for implementation are realistic and safe and do not cause an unrealistic burden on radar system operators.

AMCP WGF ACTION: Review the revised question


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Working Party 8B

REPLY TO LIAISON STATEMENTS OF TASK GROUP 1/5

1 IntroductionWorking Party 8B has received several liaison statements from Task Group 1/5 since our last meeting in February 1999*. At the February 1999 meeting of Working Party 8B, the Chairman of Working Party 8B established a Radar Correspondence Group recognizing the accelerated meeting schedule of Task Group 1/5, and urged their participation in Task Group 1/5 meetings.At the request of the Chairman of Task Group 1/5, members of the Radar Correspondence Group attending the Task Group 1/5 were asked to form a Joint Radar Correspondence Group (JRCG) involving participation of Working Party 8B and Task Group 1/5 members. Recognizing the importance of reaching agreement on matters associated with emission masks and measurements procedures for primary radar systems, the JRCG was formally established. Pursuant to the goals of the JRCG, a formal meeting of the JRCG was held in June 2000 at the Maritime and Coastguard Agency, Southampton, United Kingdom, resulting in agreement on out-of-band emission masks (Annex AD) and the boundary between the out-of-band and spurious emissions.The following are responses of Working Party 8B to the above source documents.

2 Out-of-Band Emissions and Measurement Techniques for Primary Radars(Document 8B/109)

Working Party 8B has noted Attachment 1, preliminary draft revision of Recommendation ITU-R SM.329-7; Attachment 2, Out-of-Band Emissions Falling into Adjacent Bands; and Attachment 3, Annex [AD], Primary Radars. These attachments have been overtaken by subsequent liaison statements from Task Group 1/5, and will be discussed later.With respect to comments on Recommendation ITU-R M.1177, Techniques for Measurement of Unwanted Emissions of Radars, Working Party 8B agrees with the views of Task Group 1/5 that additional information is needed to develop measurement capabilities and to apply the measurement techniques. Pursuant to providing the requested information, Working Party 8B, is developing a preliminary draft revision to Recommendation ITU-R M.1177 which is contained in Attachment 1. Also, Working Party 8B, was informed that a demonstration of the Direct Measurement technique contained in Recommendation ITU-R M.1177 was provided by the United States at the JRCG meeting in June 2000.

* Document 8B/109 (Document 1-5/TEMP/119(Rev.1))Document 8B/110 (Document 1-5/TEMP/112(Rev.3))Document 8B/114 (Document 1-5/TEMP/149(Rev.1))Document 8B/118 (Document 1-5/TEMP/159(Rev.1))


INTERNATIONAL TELECOMMUNICATION UNION

RADIOCOMMUNICATIONSTUDY GROUPS

Document 1-5/64-E24 October 2000English only

Source: Document 8B/TEMP/12

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3 Boundary Between Spurious and Out-of-Band Emissions (Document 8B/110)Working Party 8B has reviewed the Attachments to the liaison statement. With respect to Attachment 2, Variation of the Boundary Between Out-of-Band and Spurious Emissions, the text in Section 3.3 of Annex 8 of Recommendation ITU-R SM.329-8; should be modified to reflect the agreement reached in the JRCG. Working Party 8B have discussed this matter and propose the following text for Section 3.3:“3.3 Primary radars in the radiodetermination serviceAccording to further recommends 2.3 of this Recommendation and RR Appendix S3, the spurious emission region generally begins at a frequency separation equal to 250% of the necessary bandwidth, with exceptions for certain kinds of systems, including those with digital or pulsed modulation. However, it is difficult to apply the general boundary concept of 250% of the necessary bandwidth to primary radar stations in the radiodetermination service.For the case of primary radar systems, the out-of-band emission mask rolls off at 20 dB per decade from the 40 dB bandwidth to the spurious limit specified in Table II of Appendix S3. The detailed definition of the out-of-band/spurious boundary is contained in Annex AD of Recommendation ITU-R SM {OOB}.In Annex AD (Paragraph 5) the above definition of the boundary is the subject of ongoing ITU studies with a design objective of 40 dB per decade roll-off. These studies should be completed by the Radiocommunication Assembly 2006.”Working Party 8B is requesting Task Group 1/5 or Study Group 1 to incorporate the proposed changes to Recommendation ITU-R SM.329-8 at the earliest practical date.On a related subject Working Party 8B has discussed the revision of Appendix S3 with regard to agenda item 1.8.1 of WRC-03, and in particular with regard to the boundary between out-of-band and spurious emissions for primary radars. A proposal for this revision is as follows:

“Revision of Appendix S3Add at the conclusion of Paragraph 11 as a new sub-paragraph.For primary radar stations in the radiodetermination service, the boundary between out-of-band and spurious emissions is defined as at the frequency where the out-of-band emission limits defined in Recommendation {PDNR [OOB Annex AD} are equal to the spurious emission limit defined in Table II”.

4 Protection of Safety Services from Unwanted Emissions (Document 8B/114)Working Party 8B has reviewed the above liaison statement containing a draft new Recommendation (DNR) on the Protection of Safety Services from unwanted emissions. Working Party 8B comments on the DNR are contained in Attachment 2.


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5 Liaison Statement to Working Party 8B (Document 8B/118)Working Party 8B agrees with Task Group 1/5 on the need to further study Out-of-Band emission limits of primary radars in exclusive radiodetermination bands. This subject will be discussed later in this reply in response to a subsequent liaison statement from Task Group 1/5.With respect to comments of Recommendation ITU-R M.1177, Working Party has responded to the information requested in Document 8B/109. See above discussion. Also, comments from Task Group 1/5 on the correct measurement bandwidth to determine the –20 dB bandwidth, necessary bandwidth, were taken into consideration and appropriate changes were made to Recommendation ITU-R M.1177. See Attachment 1.Working Party 8B reviewed Attachment 1, Out-of-Band Emissions Falling into Adjacent Allocated Bands, and can support the draft new Recommendation as provided. Attachment 2, Annex [AD], Primary Radars, has been overtaken by a subsequent liaison statements from the JRCG (Document 8B/2(Rev.1) and Document TG 1-5/5), and will be discussed later. Attachment 3, Working Document on the Determination of OOB Emission Masks for Primary Radars, was taken into consideration by the JRCG. Working Party 8B has no comments on Attachment 4, Out-of-Band Emission Measurements. Reference to Recommendation ITU-R M.1177 in Section 3.3 is sufficient.Attachment 5, Joint TG 1-5/WP-8B Radar Correspondence Group, Work Plan, was taken into consideration by the JRCG.

6 Joint Radar Correspondence Group, Liaison Statement to Working Party 8B(Document 8B/2(Rev.1))

Working Party 8B has reviewed the liaison statement from the JRCG. Working Party 8B supports Annex [AD], Out-of-Band Emission Limits for Primary Radars, as contained in Document 8B/2(Rev.1) and Document 1-5/5; and urges Task Group 1/5 to approve the Annex without further change. As mentioned earlier, Working Party 8B recognizes the need to further study Out-of-Band emission limits of primary radars in exclusive radiodetermination bands, and understands that further reduction of OOB emissions will enhance compatibility with other services. Pursuant to this study and the stated design objective in Annex [AD], Working Party 8B has approved a revision to Question ITU-R 202-1/8 to include out-of-band emissions, and calls for the completion of the study by the 2006 Radiocommunication Assembly.The proposed revision is contained in Attachment 3. The findings of the study will be incorporated into a Study Group 8 Recommendation.Working Party 8B noted that there was a need to complete the definitions of dBpep and dBpp. After some discussion it was concluded that this work should be finalized in TG 1-5.

Attachments: 3


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ATTACHMENT 1

(Source : Document 8B/TEMP/10 + Add. 1)

PRELIMINARY DRAFT REVISION OF RECOMMENDATION ITU-R M.1177-1*

TECHNIQUES FOR MEASUREMENT OF UNWANTED EMISSIONSOF RADAR SYSTEMS

(Question ITU-R 202/8)(1995-1997)

Summary

This Recommendation provides two techniques for the measurement of radiated radar unwanted emissions. It should be used to assess compliance with the spurious emission limits in Appendix S3 (Section II) of the Radio Regulations (RR).The ITU Radiocommunication Assembly,

consideringa) that both fixed and mobile radar stations in the radiodetermination service are widely implemented in bands adjacent to and in harmonic relationship with other services;b) that stations in other services are vulnerable to interference from radar stations with unwanted emissions with high peak power levels;c) that many services have adopted or are planning to adopt digital modulation systems which are more susceptible to interference from radar unwanted emissions;d) that under the conditions stated in a) through c), interference to stations in other services may be caused by a radar station with unwanted emissions with high peak power levels;

* This Recommendation should be brought to the attention of the International Maritime Organization (IMO), the International Civil Aviation Organization (ICAO), the International Maritime Radio Association (CIRM), the World Meteorological Organization (WMO) and Radiocommunication Study Groups 1, 4 and 9.


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e) that RR Appendix S3 specifies the maximum values of spurious emissions from radio transmitters;f) that techniques to measure radar unwanted emissions to ensure compatibility with other services require the capability to measure levels of the order of 130 dB below the radar fundamental emission,

recommends1 that measurement techniques as described in Annex 1 be used to provide guidance in quantifying radiated unwanted emission levels from radar stations, over the required frequency ranges set out in Appendix S3 (Section II) of the Radio Regulations;2 that results of such usage of this Recommendation be reported to ITU-R, in order to determine any limitations in the techniques, e.g. tolerances of measurements and repeatability over the required frequency ranges, so that confidence can be established in the measurement methods.

ANNEX 1

1 IntroductionTechniques have been developed in response to § 1 of Question ITU-R 202/8. Two techniques known as the direct and indirect methods are recommended.The direct measurement method accurately measures unwanted emissions from radars that are designed in such a way as to preclude measurements at intermediate points within the radar transmitters. Examples include those which use distributed-transmitter arrays built into (or comprising) the antenna structure.The indirect method separately measures the components of the radar and then combines the results. The recommended split of the radar is to separate the system after the “rotating joint” (Ro-Jo) and thus to measure the transmitter output spectrum at the output port of the Ro-Jo and to combine it with the measured antenna gain characteristics.Experience with these techniques has yielded repeatability of 2 dB at any given frequency and under the condition of agreed fixed measurement parameters when the spectrum of any particular radar unit is repeatedly measured.


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2 Measurement system bandwidth and detector parameters

IF bandwidth ( 0.5/T ) for fixed-frequency, non-pulse-coded radars, where T : pulse length. (E.g. if radar pulse length is 1 s, then the measurement IF bandwidth should be 0.5/(1 s) 500 kHz.)

( 0.5/t ) for fixed-frequency, phase-coded pulsed radars, where t : phase-chip length. (E.g. if radar transmits 26-s pulses, each pulse consisting of 13 phase coded chips that are 2-s in length, then the measurement IF bandwidth should be 0.5/(2 s) 250 kHz.)

(0.5 B/T )½, for swept-frequency (FM, or chirp) radars, where B : range of frequency sweep during each pulse and T : pulse length. (E.g. if radar sweeps (chirps) across frequency range of 1 250 - 1 280 MHz ( 30 MHz of spectrum) during each pulse, and if the pulse length is 10 s, then the measurement IF bandwidth should be: 0.5((30 MHz)/(10 s))½ 0.87 MHz.)< (1/T) for multi-pulsemode (multi-mode) radars. For multi-mode radars, the effective value of T is determined empirically from observations of the multi-mode radar emission. The empirical observation is performed as follows: The measurement system receiver is tuned to one of the fundamental frequencies of the multi-mode radar (if the radar frequency-hops), or is tuned to a frequency within the chirp range of the radar, if the radar uses pulse compression techniques in its transmission. The measurement system IF bandwidth is set to the widest available value, and the received power level from the radar in this bandwidth is noted. The measurement bandwidth is then progressively narrowed, and the received power level is recorded as a function of the increasingly narrow bandwidths. The end result is a graph or table showing measured power as a function of measurement system IF bandwidth. The multi-mode radar's effective emission bandwidth will be the narrowest bandwidth that allows the full power level (or within 5 dB of the full power level) into the measurement system receiver. The measurement system IF bandwidth should be less than this bandwidth.

Video bandwidth Measurement IF bandwidthDetector: positive peak

3 Direct methodThe direct method described below can be used to measure unwanted emissions (out-of-band and spurious) from radar systems, and has been used to measure the emission characteristics of radar systems operating at frequencies up to 24 GHz, transmitter output powers of several megawatts, and effective isotropically radiated power (e.i.r.p.) levels in the gigawatt range. This direct method may also be carried out in an anechoic chamber.

3.1 Measurement hardware and softwareA block diagram of the type of measurement system required for this method is shown in Fig. 1. The first element to be considered in the system is the receive antenna.


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The receive antenna should have a broadband frequency response, at least as wide as the frequency range to be measured. A high-gain response (as achieved with a parabolic reflector) is usually also desirable. The high gain value permits greater dynamic range in the measurement; the narrow antenna beamwidth provides discrimination against other signals in the area; the narrow beamwidth minimizes problems with multipath propagation from the radar under measurement; and spectrum data collected with a parabolic antenna require a minimum of post-measurement correction, as discussed in the next paragraph. The antenna feed polarization is selected to maximize response to the radar signal. Circular polarization of the feed is a good choice for cases in which the radar polarization is not known a priori. The antenna polarization may be tested by rotating the feed (if linear polarization is used) or by exchanging left and right-hand polarized feeds, if circular polarization is being used.Corrections for variable antenna gain as a function of frequency should be considered. Antenna gain levels are usually specified relative to that of a theoretically perfect isotropic antenna, in units of dBi. The effective aperture of an isotropic antenna decreases as -20log(f), where f is the frequency being measured. This means that, if the measurement antenna has a constant effective aperture (that is, has an isotropic gain that increases as 20log(f)), no corrections for variable antenna gain need be performed. This requirement is met by a theoretically perfect parabolic reflector antenna, and is one of the reasons that such an antenna is preferred for a broadband radar spectrum measurement. Conversely, to the extent to which the gain of the measurement antenna deviates from a 20log(f) curve (including a less-than-ideal parabolic antenna), the resulting measurements must be corrected for such deviation.The cable connecting the measurement antenna to the measurement system should also be considered. A length of low-loss radio frequency (RF) cable (which will vary depending upon the circumstances of measurement system geometry at each radar site) connects the antenna to the RF front-end of the measurement system. As losses in this piece of line attenuate the received radar signal, it is desirable to make this line length as short, and as low-loss, as possible.


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R

R

FIGURE 1

Block diagram for measurement of radiated spurious emissionsfrom radars using the direct method

Measurement system RF front-end

Spectrumanalyser

PC-typecomputer

Variable RFattenuatorvariable RF(GPIB controlfrom computer)

Tracking bandpassfilter(e.g., YIG filter)

Low-noisepreamplifier (LNA)

Optional notch,bandpass, orother filter

Low-loss RF line;as short as possiblebetween antenna andmeasurement systeminput port

YIG trackingvoltage GPIB bus

GPIBbus

Noise diode calibrationperformed at this point

Measurement antenna:parabolic, with

appropriate feed

Radar antenna(rotating normally)

Filter, used toattenuate radar centrefrequency for measurementsat radar harmonicfrequencies

Control ofmeasurement systemand recording of data

Fixed RF attenuationused to optimizemeasurement systemgain/noise figuretrade-off

LNA used toimprove spectrumanalyser noise figure

D01

The RF front-end is one of the most critical parts of the entire measurement system. It performs three vital functions. The first is control and extension of measurement system dynamic range through the use of variable RF attenuation. The second is bandpass filtering (preselection) to prevent overload of amplifiers by high-amplitude signals that are not at the tuned frequency of the measurement system. The third is low-noise preamplification to provide the maximum sensitivity to emissions that may be as much as 130 dB below the peak measured level at the radar fundamental. Each of these sections in the RF front end is considered below.


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The RF attenuator is the first element in the front-end. It provides variable attenuation (e.g. 0-70 dB) in fixed increments (e.g. 10 dB/attenuator step). Use of this attenuator during the measurement extends the instantaneous dynamic range of the measurement system by the maximum amount of attenuation available (e.g. 70 dB for a 0-70 dB attenuator). The key to using this attenuator effectively in a radar measurement is to tune the measurement system in fixed-frequency increments (e.g. 1 MHz), called steps, rather than to sweep across the spectrum, as is more conventionally done with manually controlled spectrum analysers. At each fixed-frequency step, the attenuator is adjusted to keep the radar peak power within the dynamic range of the other elements in the measurement system (often the front-end amplifier and the spectrum analyser log amplifier are the limiting elements). With the front-end RF attenuator properly adjusted at each step, a measurement of the radar power at that frequency is performed. In this way, a nominal 60 dB dynamic range for the measurement system is extended by as much as 70 dB, to a total resulting dynamic range of 130 dB. In principle, this attenuator and the stepped-frequency measurement algorithm that it necessitates could be manually controlled, but in practice, control of the frequency-stepping and the attenuator settings via computer is more efficient and more practical.The next element in the front end, the tunable bandpass filter preselector is necessary because of the need to measure low-power spurious emission levels at frequencies that are adjacent to much higher-level fundamental emissions. For example, it may be necessary to measure spurious emissions from an air traffic control radar at 2 900 MHz that are at a level of –120 dBm in the measurement circuitry, while the fundamental emission level is at +10 dBm and is only 150 MHz away in frequency (at 2 750 MHz). The measurement system requires an unattenuated low-noise amplifier (LNA) to measure the spurious emission at 2 900 MHz, but the amplifier will be overloaded (and thus gain-compressed) if it is exposed to the unattenuated fundamental emission at 2 750 MHz. For this reason, attenuation that has frequency-dependence is required in the front-end at a position before the LNA input. In practice, this tunable bandpass filtering is effectively provided by varactor technology (below 500 MHz) and by yttrium-iron-garnet (YIG) technology (above 500 MHz). The applicable filters may be procured commercially, and should be designed to automatically track the tuned frequency of the measurement system.The final element in the RF front-end is an LNA. An LNA installed as the next element in the signal path after the preselector. The low-noise input characteristic of the LNA provides high sensitivity to low-amplitude spurious radar emissions, and its gain overdrives the noise figure of the rest of the measurement system (e.g. a length of transmission line and a spectrum analyser).The sensitivity and dynamic range of the measurement system are optimized by proper selection of LNA gain and noise figure characteristics. It is desirable to minimize noise figure while providing enough gain to accommodate all measurement circuitry after the LNA (essentially the RF line loss after the front end, plus the noise figure of the spectrum analyser circuitry). Ideally, the sum of the LNA gain and noise figure (which is the excess noise produced by the LNA with a 50-ohm termination on its input) should be approximately equal to the noise figure of the remaining measurement system. For example, assume that the spectrum analyser noise figure is 25 dB and the RF line loss between the RF front end and the analyser is 5 dB. Thus the front-end LNA must accommodate a total noise figure of 30 dB. The sum of the LNA gain and noise figure should


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therefore be approximately 30 dB in this example. A combination for such an LNA would be 3 dB noise figure and 27 dB gain.Typical spectrum analyser noise figures are 25-45 dB (varying as a function of frequency), and transmission line losses may typically be 5-10 dB, depending upon the quality and the length of the line. As a result of variation in measurement system noise figure as a function of frequency, a variety of LNAs used in frequency octaves (e.g. 1-2 GHz, 2-4 GHz, 4-8 GHz, 8-18 GHz, 18-26 GHz, and 26-40 GHz) may be required. Each LNA can be optimized for gain and noise figure within each frequency octave. This also helps match LNAs to octave breaks between various YIGs (e.g. 0.5-2 GHz, 2-18 GHz, etc.). Use of an LNA after the preselector (and, if required, a cascaded LNA at the spectrum analyser input) may reduce the overall measurement system noise figure to about 10-15 dB. This noise figure range has been found to be adequate for the measurement of broadband radar emission spectra with dynamic range as high as 130 dB.Another option for LNA configuration is one in which LNAs are cascaded. The first LNA is placed between two stages within the YIG or varactor bandpass preselector filter. It has low noise figure, but only enough gain to accommodate the insertion loss of the second YIG stage. A second (possibly lower-performance) LNA is placed immediately after the YIG. This option will provide somewhat lower overall system noise figure because the second stage of the YIG is accommodated by the first LNA. However, this option may require more advanced design and engineering modifications to the preselector filter than an administration may deem practical.A third option for the measurement system LNA configuration, and one not requiring any redesign or retrofitting of the front end preselector filter, is to place a lower-gain LNA in the front end and a second LNA at the spectrum analyser signal input. The first LNA is selected to have very low noise figure and just enough gain to accommodate the RF line loss and the noise figure of the spectrum analyser LNA. The spectrum analyser LNA, in turn, is selected for a gain characteristic that is just adequate to accommodate the spectrum analyser's noise figure in the appropriate frequency range of the radar measurement. This set of two cascaded LNAs may be more easily acquired than a single, extremely high-performance LNA, and will typically be less susceptible to overload because the 1 dB compression points can be expected to be higher than those for individual high-performance LNAs. The remainder of the RF measurement system is expected to be essentially a commercially available spectrum analyser. Any spectrum analyser which can receive signals over the frequency range of interest, and which can be computer-controlled to perform the stepped-frequency algorithm, can be used. As noted above, the high noise figure of currently available spectrum analysers must be accommodated by low-noise preamplification if the measurement is to achieve the necessary sensitivity to observe most spurious emissions.The measurement system can be controlled via any computer which has a bus interface (GPIB or equivalent) that is compatible with the computer controller and interface card(s) being used. In terms of memory and speed, modern PC-type computers are quite adequate. The measurement algorithm (providing for frequency stepping of the spectrum analyser and the preselector, and control of the front-end variable attenuator) must be implemented through software. Some commercially available software may approach fulfilment of this need, but it is likely that the measurement organization will need to write at least a portion of their own measurement software. While the development of software requires a significant resource expenditure, practical experience with such systems has shown such an investment to be worthwhile if radar emission measurements are to be performed on a frequent and repeatable basis.


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Data may be recorded on the computer's hard drive or on a removable disk. Ideally, a data record is made for every 100-200 measurement steps, so as to keep the size of data files manageable, and to prevent the loss of an excessive amount of data if the measurement system computer or other components should fail during the measurement.

3.2 Measurement system calibrationThe measurement system is calibrated by disconnecting the antenna from the rest of the system, and attaching a noise diode to the RF line at that point. A 25 dB excess noise ratio (ENR, where ENR = (effective temperature, oK, of noise diode/ambient temperature, oK)) diode should be more than adequate to perform a satisfactory calibration, assuming that the overall system noise figure is less than 20 dB. The technique is standard Y-factor, with comparative power measurements made across the spectrum, once with the noise diode on and once with the noise diode off.The noise diode calibration results in a table of noise figure values and gain corrections for the entire spectral range to be measured. The gain corrections may be stored in a look-up table, and are applied to measured data as those data are collected. Appendix II to Annex 1 describes the calibration procedure in more detail.The measurement antenna is not normally calibrated in the field. Correction factors for the antenna (if any) are applied in post-measurement analysis.

3.3 Measurement procedureAppendix III to Annex 1 describes the Direct Method in detail; this section provides a summary of the method. In addition to the parameters listed in § 2, the spectrum analyser should be set up as follows:

Spectrum analyser centre frequency:

lowest frequency to be measured. (E.g. if radar centre frequency is 3 050 MHz, but the spectrum is to be measured across 2 - 6 GHz, then initial spectrum analyser centre frequency would be 2 GHz.)

Spectrum analyser frequency span

0 Hz. (Analyser is operated as a time-domain instrument.)

Spectrum analyser sweep time

radar beam rotation interval. (E.g. if radar rotates at 40 r.p.m., or 1.5 s per rotation, then sweep time should be 1.5 s; 2 s would be a reasonable selection.)

With the radar antenna beam scanning normally, and with the measurement system set up as described above, the first data point is collected. A data point consists of a pair of numbers: measured power level and the frequency at which the power level was measured. For example, the first data point for the above measurement might be -93 dBm at 2 000 MHz. The data point is collected by monitoring the radar emission at the desired frequency, in a frequency span of 0 Hz, for an interval slightly longer than that of the radar rotation. This time-display of the radar antenna beam rotation will be displayed on the spectrum analyser screen. The highest point on the trace will normally represent the received power when the radar beam was aimed in the direction of the measurement system. That maximum received power value is retrieved (usually by the control computer, although it could be written down manually), corrected for measurement system gain at that frequency, and recorded (usually in a data file on magnetic disk).The second measurement point is taken by tuning the measurement system to the next frequency to be measured. This frequency is optimally equal to the first measured frequency plus the measurement bandwidth (e.g. if the first measurement was at 2 000 MHz and the measurement


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bandwidth were 1 MHz, then the second measured frequency would be 2 001 MHz). At this second frequency, the procedure is repeated: measure the maximum power received during the radar beam rotation interval, correct the value for gain factor(s), and record the resulting data point.This procedure, which consists of stepping (rather than sweeping) across the spectrum, continues until all of the desired emission spectrum has been measured. The stepping process consists of a series of individual amplitude measurements made at predetermined (fixed-tuned) frequencies across a spectrum band of interest. The measurement system remains tuned to each frequency for a specified measurement interval. The interval is called step-time, or dwell. The dwell time for each step is specified by the measurement system operator, and is normally equal to the IF bandwidth of the measurement system. For example, measurements across 200 MHz of spectrum might use 200 steps at a 1 MHz step interval and a 1 MHz IF bandwidth (ideally paired with a 1 sec pulse width transmitted by the radar). Computer control of the measurement system is desirable if this process (step, tune, measure, correct for gain, and repeat) is to be performed with efficiency and accuracy.The stepped technique is required for the insertion of RF attenuation at the front-end of the measurement system as the frequencies approach the centre frequency (and any other peaks) of the radar spectrum. This ability to add attenuation on a frequency-selective basis makes it possible to extend the dynamic range available for the measurement to as much as about 130 dB, if a 0-70 dB RF attenuator is used with a measurement system having 60 dB of instantaneous dynamic range. This is of great benefit in identifying relatively low-power spurious emissions. To achieve the same effect with a swept-frequency measurement, a notch filter could be inserted at the centre frequency of the radar, but there would be no practical way to insert a notch filter for all the other high-amplitude peaks that might occur in the spectrum.It is important to provide adequate bandpass filtering at the front-end of the measurement system, so that strong off-frequency signal components do not affect the measurement of low-power spurious components.These measurements may be performed without the radar antenna being rotated, provided that the directions of both maximum fundamental emission and any unwanted emission are known.

4 Indirect methodFigure 2 illustrates a recommended component separation for the Indirect method. In this Indirect method, where unwanted emissions are measured at the Rotating-Joint and then, combined with the antenna characteristics measured separately at distances of 5 m and 30 m with appropriate far-field correction, the procedure is:a) make measurements of a radar transmitter emissions at the Rotating-Joint (Ro-Jo) with a

feeder (as shown in Figure 3);b) then make separate measurements of a radar antenna maximum gain at the emission

frequencies found in step a). Here, measurements are made at the distances of 5 m for frequencies below 5 GHz and 30 m for frequencies above 5 GHz (as shown in Figure 4);

c) correct the measured gains with an appropriate correction factor (using a software program, given in Appendix I, for the frequencies, at which the emissions were observed in step a));

d) finally, steps a) and c) are combined to obtain the Indirect e.i.r.p. radiation at the observed unwanted emission frequencies.


- 16 -

Radartransmitter

Antenna

Coaxial cable

Recommended componentseparation for indirect method

Transmitter outputin WG 10

Rotatingjoint

FIGURE 2Typical radar system

D02


- 17 -

FIGURE 3

Measurement at the rotating-joint port

Radars

Spectrumanalyser

EIA right-angleadaptor

Waveguide toEIA adaptor

Short or long feederRotating joint

Specialattenuator

Measuring cable

A coaxial attenuator ora notch filter is needed

in WG 10 and WG 12 tofurther enhance the

measuring sensitivity

Waveguide toN-typeadaptors

WaveguidetransitionsWG 10-12WG 10-14WG 10-16WG 10-18

D03


- 18 -

4.1 Methods of measurement and problems associated with a waveguideThere are two main problems in measuring the transmitter output power spectrum. The one is accessing the higher frequency components of the transmitted spectrum without distortion and; the other is measuring very low level emissions in the presence of the fundamental transmitting pulse of perhaps 60 kW peak power.In any waveguide, the propagation mode, TE10, can be measured using a calibrated measuring system. The characteristic of such a system is such that it attenuates the powerful fundamental signal sufficiently to protect the measuring equipment, at other frequencies offers a negligible attenuation and energy is being measured in the TE10 mode.However, it is recognized that with radars employing magnetrons, the spurious frequency emissions of the transmitter output could be in higher order modes at any time and the energy levels may be greater than that in the fundamental mode. Determination of modal content at the transmitter output is, potentially, expensive and technically may not be of significance anyway, because it is most probable that higher order modes may get trapped in a waveguide to coaxial adaptor, or in antenna feeder and the Ro-Jo connecting to the radar antenna. (i.e. waveguide to coaxial adaptors are only designed to couple energy in TE10 mode).

4.2 The measurement system for the measurement of unwanted emissions in a waveguide

This measuring system allows the measurement of low levels of emissions accurately in the presence of high power radar pulses.The main components of the system are a notch filter and a set of waveguide tapers, from WG 10 to smaller waveguide sizes, to cover the whole frequency range of interest. The notch filter comprises of a straight WG 10 waveguide with absorbent elements inside, which attenuates the fundamental signal while at other frequencies it offers negligible attenuation. To achieve the required attenuation to protect the measuring equipment, and to measure emissions at higher frequencies, linear tapers are used at the output of the notch filter.The waveguide taper is a high pass filter and thus rejects, by reflecting back, signals below the cut off frequency. If a taper had been used directly at an output port of a radar transmitter, the fundamental would have been reflected back into the transmitter causing an undesirable mismatch. But with the taper after the notch filter the reflected signals are absorbed a second time. Thus the return loss at the fundamental frequency is typically 34 dB, which is low enough to avoid frequency pulling of the magnetron.Frequencies above the cut off are transmitted through the transitions and into the measuring equipment. If possible, a short waveguide section, should be included to prevent coupling of evanescent modes between a taper and a waveguide to coaxial transition.

4.3 Results of measurement at the Ro-Jo portThe measurement technique comprises an exploratory search of a frequency band of interest to locate and tag significant spurious emissions by frequency, followed by a revisit to each noted emission for detailed and accurate measurement of maximum amplitude of that emission.

4.4 Measurement uncertainty in a waveguideThe system has a measurement accuracy of 1.3 dB across the frequency band 2 to 18.4 GHz for the waveguide port. Total uncertainties with a confidence level of not less than 95% can be calculated to be 3.4 dB for the waveguide port including the spectrum analyser.


- 19 -

4.5 Measurement of antenna gain characteristic at measured emission frequenciesThis indirect method recommends that near-field measurements be made on the antenna on an Open Area Test Site (OATS) at distance of 5 m for frequency below 5 GHz and 30 m for frequencies above 5 GHz. Correction factors are then applied to correct the measurement to an equivalent far field gain, which provide an acceptable correlation with the far field gain. A typical measurement arrangement is shown in Figure 4.

FIGURE 4Near field gain measurement arrangement for 5 m and 30 m distances

Signalgenerator

Directionalcoupler

Calibratedtest horns

Turntable

TX cable Radar antenna

Earth plane

Measuringequipment

Antenna mast

RX cable

Heightsearch1-4 m

Fixedheight1.5 m

Separation distance:5 m for frequencies less than 5 GHz30 m for frequencies above 5 GHz

D04

4.6 Near field gain measurement procedure for 5 m and 30 m distancesThe measurement of maximum gain of the Antenna Under Test (AUT) shall be carried out at spurious and out-of-band frequencies measured or identified, using the method specified in subclause 4.3. At each measured, or identified, emission frequency, the gain of AUT shall be maximized by first rotating through 360% and then further maximized by moving the test horn up, or down. The gain of the AUT is obtained by measuring e.i.r.p. at each distance with a known level of power into the AUT at each frequency of interest. Equations (1) and (2) show details of calculations to arrive at the equivalent far field gain (Ga) of the AUT from the measured spectrum analyser level (S).

Ga of the AUT (dBi) = Measured e.i.r.p. (dBm) - Pinput (dBm) + Gc (dB) (1)

Measured e.i.r.p. (dBm) = S (dBm) + - Gr (dBi) (2)

where:Ga = Equivalent far field gain of the AUT (dBi)

Pinput = Power input into the AUT (dB)Gc = Gain correction factors for 5 m and 30 m distances, which can be

calculated for the AUT using a software program specified in Appendix I


- 20 -

S = Measured spectrum analyser level (dBm)Gr = Gain of the receiving test horn antenna (dBi)

d = measuring distance (m)l = wavelength of a frequency of interest (m)

4.7 Gain correction and reduction factorsThe software program gives the far field correction factors from a near field measurement. The program derives the correction factor for each distance at the frequency of interest by considering the phase changes of the received wave across the linear antenna. (At near distances the wave front is spherical and not linear.) Therefore, it can be used to infer the maximum antenna gain at infinity from a near field measurement.An important point to bear in mind is that the antenna gain pattern is not addressed. It must be noted that at spurious frequencies the electrical length of the antenna is different from the mechanical length; it may well be much shorter. This is due to the different illumination pattern of the antenna length at frequencies other than the designed frequency. A copy of the program is given in Appendix I.

4.8 Near field gain measurement uncertainty with the applied correction factorsThe worst-case measurement uncertainty can be calculated to be 6 dB, which includes, uncertainties due to a spectrum analyser, test horn gain, cable loss and source and site imperfection. Total uncertainties with a confidence level of not less than 95% can be calculated to be 4.2 dB.The derivation of the correction factors for these distances assumes the AUT radiating aperture to be constant at all frequencies.

4.9 Producing a radar transmitter emission spectrum as an e.i.r.p. by combining measured emissions and antenna gain characteristic

The technique used to obtain a maximum value for omnidirectional e.i.r.p. is to add, for each emission frequency, the maximum power generated by radar transmitter (dBm), to the maximum directional gain (dBi) from the AUT. This means one only has to characterize the AUT at frequencies at which the radar transmitter emissions were observed.The effects of the AUT mismatch are considered to be taken into account automatically in the measurements of gain, because the test equipment is matched to 50 ohms, the nominal impedance of the coaxial connectors and the emissions are measured in the 50 ohms measuring receiver.

4.10 SummaryThe indirect method, which is cost effective in time and facilities, is sensitive enough to allow measurement of low level emission values with a reasonable accuracy and repeatability. Furthermore, it can be used in all weather conditions. With this indirect method, the measurement frequency range can easily be extended to 40 GHz or higher.


- 21 -

APPENDIX I

TO ANNEX 1

Calculation of gain correction factors for a planar antenna array using a software program written in BASIC

'**************************************************************************This program is written, in BASIC, to determine the far field from a near field measurement. Uses only the considerations of the phase changes of the received wave due to the difference between the spherical RF wavefront and the planar antenna array. Thus the program should only be used to determine the boresight or maximum antenna gain at infinity from a near field measurement. Antenna gain pattern is not addressed here.

'***************************************************************************'Test data for error -.025 pi radians ; error ~.3 dB

'freq = 3000'l = 10

'd = 1'

CLS'

INPUT "Enter the antenna frequency in MHz "; freqINPUT "Now enter the measuring distance in metres from the antenna "; l

INPUT "Enter the maximum dimension of the antenna in metres "; d'

''

CONST c = 300CONST pi = 3.141592654#

''

lamda = c / freqnum = 100

''


- 22 -

IF d < (5 * lamda) THEN PRINT "Antenna dimensions should be much greater (* 5) than";

PRINT " the wavelength for accurate use of this prog" STOP

END IF'sum of inphase and quadrature field elements

sumi = 0sumj = 0

'' system is symmetrical so integrate from 0 to d/2

FOR i = 0 TO num - 1 dprime = i * d / (2 * (num - 1))

phasediff = (l - ((l ^ 2) + (dprime ^ 2)) ^ .5) * 2 * pi / lamda' PRINT " phase diff is ";

' PRINT USING "##.##"; phasediff; icomp = COS(phasediff)

sumi = sumi + icomp jcomp = SIN(phasediff)

sumj = sumj + jcompNEXT i

PRINT " Max phase error is ";PRINT USING "##.##"; phasediff / pi;

PRINT " * pi rads"'form final received planar power received from spherical RF wave

res = ((sumj) ^ 2 + (sumi) ^ 2) ^ .5'PRINT "Result is "; res; "i is "; i; " num is "; num

'Calc gain reductiongprime = num / res

'glog = 20 * (LOG(gprime) / LOG(10#))

PRINT "Gain reduction from infinite far field is ";PRINT USING "##.### "; glog;

PRINT " dB"END


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APPENDIX II

TO ANNEX 1

Gain and noise figure calibration using a noise diode

Measurement system calibration should be performed prior to every radar emission spectrum measurement. As measurements are performed, gain corrections may be added automatically to every data point. For measurement system noise figures of 20 dB or less, noise diode Y-factor calibration (as described below) may be used. This Appendix describes the theory and procedure for such calibration.

TheoryThe noise diode calibration of a receiver tuned to a particular frequency may be represented in lumped-component terms as shown in Figure 1. In this diagram, the symbol represents a power-summing function that linearly adds any power at the measurement system input to the inherent noise power of the system. The symbol g represents the total gain of the measurement system. The measurement system noise factor is denoted by nf, and the noise diode has an excess noise ratio denoted as enr. (In this Appendix, all algebraic quantities denoted by lower-case letters, such as "g," represent liner units. All algebraic quantities denoted by upper case letters, such as "G," represent decibel units).


- 24 -

FIGURE 1

Lumped component diagram of noise diode calibration

Noise factor is the ratio of noise power from a device, ndevice(W), and thermal noise,

where k is Boltzmann's constant (1.38·10-23W·s/k, Watt-seconds per degree kelvin), T is system temperature in kelvin, and B is bandwidth in hertz. The excess noise ratio is equal to the noise factor minus one, making it the fraction of power in excess of kTB. The noise figure of a system is defined as 10 log (noise factor). As many noise sources are specified in terms of excess noise ratio, that quantity may be used.In noise diode calibration, the primary concern is the difference in output signal when the noise diode is switched on and off. For the noise diode = on condition, the power, Pon(W), is given by:

where nfs is system noise factor and enrd is the noise diode enr.When the noise diode is off, the power, Poff(W), is given by:

The quantity k, Boltzmann's constant, is 1.3810-20 mW s/K (milliwatt seconds per kelvin). T is the system noise temperature in kelvin, and B is the bandwidth in hertz. The ratio between Pon and Poff is the Y factor:


- 25 -

Hence the measurement system noise factor can be solved as:

The measurement system noise figure is:

Hence:

or

In noise diode calibrations, the preceding equation is used to calculate measurement system gain from measured noise diode values.Although the equation for NFs may be used to calculate the measurement system noise figure, software may implement an equivalent equation:

And substituting the expression for gain into the preceding equation yields:

The gain and noise figure values determined with these equations may be stored in look-up tables. The gain values are used to correct the measured data points on a frequency-by-frequency basis.Excluding the receive antenna, the entire signal path is calibrated with a noise diode source prior to a radar spectrum measurement. A noise diode is connected to the input of the first RF line in place of the receiving antenna. The connection may be accomplished manually or via an automated relay, depending upon the measurement scenario. The noise level in the system is measured at a series of points across the frequency range of the system with the noise diode turned on. The noise measurement is accomplished with the IF bandwidth set to 1 MHz and the video bandwidth set to 10 Hz. The noise diode is then turned off and the system noise is measured as before, at the same frequencies. The measurement system computer thus collects a set of Pon and Poff values at a series of frequencies across the band to be measured. The values of Pon and Poff are used to solve for the gain and noise figure of the measurement system in the equations above.


- 26 -

APPENDIX III

TO ANNEX 1

Direct method detailed description of procedures and software

The direct method assumes that the following conditions can be met:1) The far field radiation zone of a radar can be accessed by a measurement system as

described in the body of this Annex;2) Unwanted feed-through of radar signals directly into the measurement system hardware

(i.e. bypassing the measurement system antenna) can be minimized to a sufficiently low level to ensure that measurement results are accurate.

The direct method does not require that the radar operation be coordinated with the measurement system, although in some cases cooperative operation may be beneficial in expediting the measurement.The direct method process is as follows:Step 1: Determine a measurement location. The measurement location should be within or as nearly as possible to the radar main radiation beam. For surface search radars and some other radar types, this may be relatively easy, as the radar beam will sweep across the surface, and the measurement system need only be placed within this area. For many air search radars, however, the main beam does not directly illuminate the ground. For these radars, the measurement system should be located within the maximum coupling zone on the surface. This zone may be determined by tuning the measurement system to the radar fundamental frequency and then driving the measurement system in a vehicle from a position close to the radar to a position far (on the order of a few kilometres) from the radar. The measurement system is used to monitor received signal level as a function of position. This can be done by running a spectrum analyser in a zero frequency span with a sweep time of 500 seconds, and watching the peak level every few seconds when the radar sweeps past the vehicle. The result is a time display that shows the maximum coupling location(s).Any place within the maximum coupling zone should be adequate. In practice, this zone has been found to begin no closer than about 0.75 km from air search radars, and to extend to no further than about 2 km from the same radars. There is usually no sharply defined point where maximum coupling occurs, but rather a broad zone within these limits.The question of multipath should be considered. Multipath effects have been observed very rarely. When they have been observed, it has been in cases in which the radar and the measurement system were separated by calm, smooth water surfaces. In other cases, irregular intervening terrain and the use of parabolic reflector antennas by the measurement system minimize multipath effects to an extent that makes them negligible. Multipath effects can be checked by repeating the radar measurement at a second location and comparing the results from the two measurement locations. Multipath is also believed to be minimized by raising the measurement antenna on a telescoping mast to a height of about 10 meters above the ground. This also provides a better line-of-sight between the radar and the measurement system.Step 2. Set up the measurement system and check for unwanted feed-through signals. The measurement system is configured with a parabolic reflector antenna at the top of a 10 metre mast (optional), or at a height of at least a few metres above the ground, to avoid multipath effects and provide reasonably good line-of-sight propagation. The measurement system should be tuned to the radar fundamental frequency or maximum emission frequency, if it is chirped or frequency-hopping.


- 27 -

When this is accomplished, it is necessary to check for unwanted feed-through (i.e. the unwanted reception of radar energy within the measurement equipment, bypassing the measurement antenna). Feed-through is checked by disconnecting the measurement antenna and terminating the input line with a 50-ohm load. If feed-through is present, the following options may be exercised:1) check to ensure measurement equipment racks (if any) are sealed;2) check connectors for firm fittings;3) move the radar measurement system to an alternative location, in which the

measurement equipment is shielded from the radar by buildings or foliage, and in which the antenna is raised above these obstacles on the telescoping mast;

4) move the radar measurement system to a larger distance from the radar.A well-designed measurement system should minimize the possibility of unwanted feed-through.Step 3. Determine radar emissions parameters. The parameters that are most critical to determine before the measurement begins are beam scanning interval and effective emission bandwidth. Beam scanning interval and other characteristics are acquired by tuning the spectrum analyser in a zero span mode and a sweep time interval of several seconds, and then observing the beam scanning of the radar.Determination of the emission bandwidth is accomplished as described in the main body of this Annex, with the spectrum analyser tuned to the radar fundamental frequency in a zero span mode, and the IF and video bandwidths initially set to their widest available values. The IF bandwidth is then reduced each time the radar beam swings past the measurement system, and the bandwidth at which the received power level drops is noted. This is the widest available measurement bandwidth that is less than the radar emission bandwidth. This will be the measurement bandwidth used, unless circumstances such as a need to observe the radar in a particular receiver bandwidth dictate otherwise.Additional radar emission parameters that should be noted are: pulse repetition rate, pulse jitter (if any), pulse stagger (if any), and pulse width (as measured on an oscilloscope connected to the spectrum analyser video output).Step 4. Calibrate the measurement system. See Appendix II of this Annex. Noise diode calibration is recommended, although alternative methods using signal generators can be used.Step 5. Configure measurement system software. The measurement software must be configured to the desired start frequency (MHz), stop frequency (MHz), step size (MHz), step interval (MHz), IF bandwidth (MHz), video bandwidth ( IF bandwidth), detector (positive peak), spectrum analyser reference level (usually –10 dBm), initial attenuation at the start frequency (usually zero dB), and additional data as location, radar name, project name for the measurement, etc.Step 6. Check for linearity during the measurement. It is critical to maintain the integrity of the measurement by checking for linearity as the measurement progresses. When measuring both at the fundamental frequency and in the spurious emissions, system linearity should be checked by periodically inserting 10 dB of RF attenuation at the rf front end, ahead of the LNA. The result should always be a 10 dB drop in measured signal level. If more than a 10 dB drop is observed, overload of the LNA may be occurring. If less than a 10 dB drop is observed, then unwanted feed-through may be occurring. Good system design will minimize these potential problems. If they do occur, it may alternatively be necessary to either take additional steps to shield the measurement system, or else to move to another location, as described in Step 2, above.


- 28 -

Step 7. Measure the radar in more than one IF bandwidth (recommended but not required). It may be useful to measure radar emissions in several bandwidths. Such measurements provide an unequivocal indication of the variation in measured radar power as a function of receiver bandwidth at any given frequency in the spectrum.


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ATTACHMENT 2

(Source: Document 8B/TEMP/11)

COMMENTS ON LIAISON STATEMENT FROM TG 1/5 CONCERNING PRELIMINARY DRAFT NEW RECOMMENDATION ON PROTECTION OF

SAFETY SERVICES FROM UNWANTED EMISSIONS

Working Party 8B wishes to suggest possible additions and modifications to the above preliminary draft new Recommendation (Document 8B/114), as shown in the attachment to this document.New text is shown underlined whilst text for removal is shown in strikethrough.

Attachment: 1


- 30 -

ATTACHMENT (TO ATTACHMENT 2)(Source: Document 1-5/TEMP/140(Rev.2))

PRELIMINARY DRAFT NEW RECOMMENDATION ITU-R SM.[SAF]

THE PROTECTION OF SAFETY SERVICES FROM UNWANTED EMISSIONS

The ITU Radiocommunication Assembly,

consideringa) that, in some cases, safety services and services employing high power transmitters have been allocated to adjacent or nearby frequency bands;b) that, in making these allocations, practical transmitter and receiver compatibility may not have been considered;c) that No. S1.59 defines a safety service as any Radiocommunication service used permanently or temporarily for the safeguarding of human life and property;d) that some services, such as those safety services concerned with safety of life or property, are based on the reception of emissions with a higher probability of integrity and availability than is generally required for other radio services;e) that No. S1.169 defines harmful interference as interference which endangers the functioning of a radionavigation service or of other safety services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance with the Radio Regulations;f) that No. S4.10 of the Radio Regulations recognizes the requirement of radionavigation and other safety services for special measures to ensure their freedom from harmful interference;g) that it is important to avoid harmful interference to safety services because of the potential for loss of life and property;h) that several footnotes of the Radio Regulations draw attention to the need for greater availability and priority for safety services in certain bands (e.g., Nos. S5.353A, S5.357A, S5.362A). High-power emissions and emissions from spaceborne or airborne stations can be particularly harmful;j) that there are various operational practices and mitigation techniques that can be used by safety services to minimize the impact of interference from other services;k) that there are various operational practices and mitigation techniques that can be used to avoid causing harmful interference to the safety services;l) that general limits for spurious emissions, such as those in Appendix S3, may not protect to the desired extent the safety services from interference;m) that WRC-97 called for ITU-R to "study those frequency bands and instances where, for technical or operational reasons, more stringent spurious emission limits than the general limits in Appendix S3 may be required to protect safety services ... and the impact on all concerned services of implementing or not implementing such limits";n) that WRC-97 called for ITU-R to "study those frequency bands and instances where, for technical or operational reasons, out-of-band limits may be required to protect safety services ... and the impact on all concerned services of implementing or not implementing such limits";


- 31 -

o) that suitable measures can be taken to avoid the potential of harmful interference to safety services,

notinga) that explanations of why safety services may need special attention with respect to interference from out-of-band or spurious emissions are presented in Annex 1;b) that ITU Radio Regulations contain definitions and terminology related to safety services (e.g., Nos. S1.28-S1.31, S1.32, S1.33, S1.36, S1.43, S1.44 S1.46, S1.47 - services, S4.10, S1.59 - general, S1.166, S1.167, S1.168, S1.669 - interference);c) that safety services can only be defined in terms of safety requirements which seek to show that the system reaches a specified integrity level under all conditions of use. In the case of protection requirements it is necessary to demonstrate that a safety system's integrity is not compromised;d) that information on past history of compatibility between safety services and other services may be useful,

recommends1 that the following measures may be taken to avoid the potential of harmful interference to safety services:a) consultation;b) agreement among safety services and other transmitting organizations; and c) appropriate spectrum management techniques including unwanted emission limits;2 that the mitigation techniques and measures described in Annex 2 be used by transmitting systems to avoid harmful interference generated by unwanted emissions, bearing in mind the constraints placed on system design;3 that the mitigation techniques and measures described in Annex 3 may be used by safety services to reduce or avoid the impact of interference from other services where they do not degrade the performance of safety service equipment;4 that where it is determined to be necessary, more stringent spurious emission limits than the general limits in Appendix S3 be used in the frequency bands in Annex 4; special cases may be resolved by using applicable ITU-R Recommendations;5 that the frequency bands listed in Annex 4 are those safety service bands where, for technical or operational reasons, out-of-band limits may be used by active services to protect safety services;6 that the level of harmful interference for safety of life systems shall be determined on a case by case basis in the form of a safety analysis. This analysis will assess the use to which the safety system is being put and demonstrate that the specified integrity level is still maintained under all conditions of use.


- 32 -

ANNEX 1

(to Document 1-5/TEMP/140(Rev.2))

Protection of safety services

Safety services are radiocommunications services used for safeguarding human life and property. For example, all aeronautical operational and air traffic control communications channels and many maritime communications channels are fundamentally safety of life channels. The systems, including radionavigation systems and radionavigation satellite systems, used for safety-of-life often depend on the ability to detect a weak or distant signal where interference can critically affect reception. This means special protection may be required for safety services as stated in RR S4.10, because of the criticality of protecting life and property. The necessity for safety systems to detect weak signals makes it important that these systems operate in an environment free from harmful interference. The international radio regulatory authorities recognize that special protection is required for the safety services. In addition to the general spurious emission limits specified in the ITU Radio Regulations, specific standards or applicable ITU-R Recommendations are required to protect some safety services. Some examples are Recommendations:ITU-R M.218-2, M.441-1, M.589-2, M.690-1, M.1088, M.1233, M.1234, M.1313, M.1317, M.1318, M.1460, M.1461, M.1463 and M.1464.

1 Aeronautical systemsFor international civil aviation, specific safety standards are specified in International Civil Aviation Organization's (ICAO) Standards and Recommended Practices, Annex 10 to the Convention on International Civil Aviation. ICAO states "The Radio Regulations also have a major concern with the prevention of interference of all kinds, whether between services or regions, between assignments, or from other sources of radiation such as industrial or medical equipment. Particular attention is accorded to services where there is a predominant safety-of-life function, as in aeronautical services."In the design of aeronautical communications, navigation, and surveillance (CNS) systems, the attributes of spectrum efficiency and robustness of system operation (e.g., adequate link margin, resistance to interference, minimal failure modes) often will be in conflict. When this is the case, it should be recognized that robustness of system design must be given priority due to the safety-critical nature of aeronautical CNS systems.

2 Space based distress alerting and location systemsDistress and safety systems operating in space stations with sensitive receivers are particularly vulnerable to interference from terrestrial emitters. Systems such as Cospas-Sarsat have fields of view that extend over thousands of square kilometres to receive and locate signals from low power satellite EPIRBs. Interference to Cospas-Sarsat in the band 406-406.1 MHz has been shown to originate from equipment in adjacent and near-adjacent bands as well as from transmitters with broadband modulation characteristics operating at frequencies as much as 20 MHz away from 406 MHz. The out-of-band and spurious emissions from high power systems that use pulse and digital modulation techniques can be at levels that completely mask reception of EPIRB transmissions.


- 33 -

Recommendation ITU-R M.[Doc. 8/84], Protection Criteria For Cospas-Sarsat Search and Rescue Processors in the Band 406-406.1 MHz, establishes the broadband signal spectral power flux-density threshold level at the input to the satellite antenna as -198.6 dB(W/m2/Hz). This document also establishes that narrow band spurious emissions should not exceed -185.8 dB(W/m2) at the input to the Sarsat antenna. Recommendation ITU-R SM.1051 also provides information on principles of EPIRB detection and location, processing of 406 MHz interfering signals, and harmful interference levels.


- 34 -

ANNEX 2


Mitigation techniques and measures that may be used at the transmitter

Several possible mitigation techniques have been described in ITU R Recommendations, such as Recommendation ITU R SM.328-10, which may have direct relevance to the categories listed below:

Practical hardware and system measures to be considered at an early stage in the design of systems in order to reduce interference from unwanted emissions• Transmitter architecture.• Design of the output power amplifier to avoid spectral regrowth of the signal into

adjacent channels, or intermodulation.• Use of components that operate with linear characteristics to the extent possible.• Design of the modulation process to avoid unwanted emissions.• Antenna patterns.• Power control.

Traffic loading management See Trunking

Band utilization• One way to avoid co-channel harmful interference is to make optimum use of frequency

reuse.• Geographic and frequency separations are standard methods of precluding harmful

interference.• Safety services are more easily protected from harmful interference due to unwanted

emissions when they are allocated frequency bands for their exclusive use.• Space-based distress alerting and location systems have sensitive receivers and the

following considerations should be addressed when planning new systems or upgrading old systems:• Proposed protection bandwidths must account for Doppler shifts due to relative

motion between the transmitter and space station. This is especially important when the transmitter is also located in space.

• Special consideration must be given to the impact of out-of-band and spurious emissions from systems employing pulse, spread spectrum, and other broadband modulation techniques. These types of systems can cause interference when the transmitter frequency is relatively near in frequency to the safety system carrier frequency.

• Desensitization of low noise amplifiers can occur when both the safety and non-safety systems are located in space. A potential for burnout of low noise


- 35 -

amplifiers also exists for cases, where orbital geometries are such that the safety and non-safety systems are in close proximity.


- 36 -

• Applicable ITU-R recommendations identifying harmful interference levels to safety systems should be used as aids to establish proper frequency separation between safety and non-safety systems.

Guard channelsChannel 16 in the marine band has been protected in the past by providing vacant channels either side of the distress and safety calling and working channels. For example, in the past channels 15 and 17 were not used in order to avoid interference to channel 16. The present Appendix S18 includes protection for channel 16 by footnotes encouraging the use of low power operation and on-board communications on channels 15, 75, 76, and 17. The use of guardbands in allocations adjacent to safety services can help to mitigate interference.

MonitoringReports of interference can be used to determine the type of interference or service being dealt with to determine whether the problem is to be dealt with by local or international monitoring stations.Facilities for monitoring from VLF through to "L" band and above and mobile monitoring teams and mobile EMC Laboratories can be used to supplement the fixed facilities.

Sector blankingOperating procedures may be established whereby the transmitter is inhibited when the radiated main beam is in the field of view of a safety service system (particularly applicable to VTS radar systems).


- 37 -

ANNEX 3


Mitigation techniques and measures that may be used by safety services to minimize harmful interference from other services

Mitigation techniques vary for different services and systems. Not all of the techniques listed below are suitable in all cases. For example, some communications and surveillance systems used by civil aviation have frequency diversity and signal processing. However, other techniques such as tailoring the antenna pattern or beam-tilting may limit the performance of some aeronautical safety systems and would not be appropriate.

Receiver architecture

Improved RF selectivity will reduce unwanted signals outside of the tuned bandwidth.Double Superheterodyne design will give both good image and adjacent channel rejection performance.

Site-shielding

Mesh fences and suitable use of local topography can provide attenuation to interfering signals.

Operational measures

The use of correct operational procedures (e.g. use of call-sign prior to passing traffic) reduces the risk of misinterpretation of unwanted signals.

Error correction and interleaving

The use of error correction coding and interleaving techniques may improve the performance of digital systems in the presence of unwanted signals.

Frequency Diversity

Where a number of channels are available for use at any time or a signal is transmitted on two or more frequencies simultaneously. If harmful interference is detected on any of the available channels, a clear channel can be selected.Signals can be either combined at the receiver or the strongest signal is selected. It should be noted that this technique is, however, spectrally inefficient.

Space Diversity

Weak signals are enhanced by the use of antennas separated in space with their outputs correlated combined at the receiver.

Beam down-tilt

Not only can the interfering signal be reduced by as much as 3dB (even co-channel) but also penetration can be increased. Antenna techniques such as "null fill" have been used to provide a better quality service.


- 38 -

Antenna pattern

Corner reflectors and other directional antennas can be used to tailor the service area of interest and minimize interference from outside the service area.


- 39 -

Signal Processing (Radar)Recommendation ITU-R M.1372 (Efficient use of the radio spectrum by radar stations in the Radiodetermination service) provides some of the methods that can be used to enhance spectrum efficiency of radar systems operating in radiodetermination bands. Several receiver post-detection interference suppression techniques currently used in radionavigation, radiolocation and meteorological radars are addressed along with system performance trade-offs (limitations) associated with the interference suppression techniques.

RF FilteringNotch filtering has successfully been used in the past to protect hyperbolic navigation systems such as Loran from harmful interference. This type of filtering can easily be used to attenuate large power signals nearby the wanted signal. Other types of filtering, such as band pass filtering etc., could also be usefully employed, where only a few channels or bands are of interest. These techniques can be applied to both transmitters and receivers.

TDMA/FDMA systemsTime and Frequency multiplexing systems can offer greater immunity to some types of interference than asynchronous and large bandwidth systems.

Digitally Coded Squelch (DCS)/Continuous Tone Control Signalling System (CTCSS)A receiver using this technique is only activated when traffic is intended for that particular unit.

MonitoringThe Cospas-Sarsat system has the ability to locate many types of interfering signals. This capability has been implemented at numerous ground stations and the information is routinely reported to administrations and ITU. An example of spectrum monitoring procedures is given in Recommendation ITU-R SM.1051-2.

TrunkingThe radio system comprises a number of channels that are available for traffic at a given time. A control signal allocates the next available working channel when a user tries to access the system. In the case where safety services are provided by the trunking systems, priority features should also be built into this system to provide instant access for priority traffic. Other systems will be able to detect interference on a working channel and automatically take the relevant channel out of service.

Path DiversityThis system is particularly applicable to CDMA systems in urban environments. A number of de-spreading circuits are employed at the receiver which decode the wanted signal contributions after successively longer finite periods of time (this is known as "rake" reception). The received signal contributions are correlated and are processed using either "switched", "equal gain" or "maximal-ratio" combining to obtain a better estimate of the message signal.

Adaptive Power ControlA mobile transmitters power can be automatically adjusted.


- 40 -

ANNEX 4


Relevant frequency bands for safety services

This Annex lists frequency bands that have been identified as being used for safety services. Some other bands under the control of national administrations may be in use for safety services, but these may not be included in the list.

Frequency band Brief description of use

70-130 kHz Hyperbolic phase comparison

90-110 kHz Hyperbolic time difference LORAN-C190-435 kHz Non-directional beacons275-335 kHz DGNSS hyperbolic RANA

1 625-1 635 kHz Hyperbolic phase comparison TORAN1 800-1 810 kHz Hyperbolic phase comparison TORAN2 160-2 170 kHz Hyperbolic phase comparison TORAN

2.1-28 MHz(various bands)

Aeronautical Mobile (In-Route and Off-Route) Service and GMDSS communications in accordance

with Article S574.8-75.2 MHz Instrument Landing System marker beacons108-118 MHz Radionavigation aids – VHF Omni-directional

Range, Instrument Landing System Localizer, terrestrial augmentation for radionavigation-satellite

systems

118-137 MHz Air-to-Ground and Ground-to-Air Safety Communications

121.45-121.55 MHz Distress Beacons: COSPAS SARSAT and Aeronautical Emergency location

156-162 MHz GMDSS Maritime Communications, Automatic Identification System

242.95-243.05 MHz Distress Beacons: COSPAS-SARSAT and Aeronautical Emergency Location

225-328.6 MHz Air-to-Ground and Ground-to-Air Safety Communications

328.6-335.4 MHz Instrument Landing System Glide Slope


- 41 -

335.4-400 MHz Air-to-Ground and Ground-to-Air Safety Communications

406.00-406.10 MHz Distress Beacon COSPAS-SARSAT (E-s), GMDSS


- 42 -

960-1 215 MHz Aeronautical radionavigation aids – Distance Measuring Equipment, Tactical Air Navigation, Radar Beacons, Secondary surveillance radar,

Airborne Collision Avoidance System Radionavigation-satellite systems

1 215-1 400 MHz Aeronautical Radar1 215-1 260 MHz Radionavigation satellite systems

1 525-1 559 MHz (s-E) Mobile satellite distress and safety communications, GMDSS and AMS(R)S)

1544-1545 MHz (s-E) COSPAS-SARSAT Distress Beacon L-band EPIRB GMDSS

1 559-1 610 MHz Radionavigation satellite systems

Terrestrial and satellite based augmentations for satellite navigation systems

1 626.5-1 660.5MHz (E-s) Mobile satellite distress and safety communications, GMDSS and AMS(R)S)

1 645.5-1 646.5 MHz L-band EPIRB (E-s) GMDSS2 700-3 300 MHz Radar (shipborne, land-based , racons and

Aeronautical), weather radar4 200-4 400 MHz Airborne Radio Altimeter5 000-5 150 MHz Microwave Landing System

Radionavigation-satellite systems5 350-5 650 MHz Radar beacons, radar on-board, Terminal Doppler

Weather Radar8 750-8 850 MHz Airborne Doppler navigation aids (radar)8 900-9 280 MHz Land-based radar, Aeronautical radar9 200-9 500 MHz Radar (shipborne), radar beacons and target

enhancers, airborne and land-based weather radar, aeronautical ground-based radar and SARTs.

13.25-13.4 GHz Airborne Doppler navigation aids (radar)15.4-16.4 GHz Airport Surface Detection Equipment

Weather radarAircraft landing systems, radar sensing and

measurement system


- 43 -

ATTACHMENT 3(Source: Document 8B/TEMP/1)

DRAFT REVISION OF QUESTION ITU-R 202-1/8*

UNWANTED EMISSIONS OF PRIMARY RADAR SYSTEMS

(1993-1997)


consideringa) that the radio spectrum available for use by the radiodetermination service is limited;b) that the radionavigation service is a safety service as specified by No. S4.10 of the Radio Regulations, and in addition that some other types of radar systems such as weather radars may perform safety-of-life functions;c) that the necessary bandwidth of emissions from radar stations in the radiodetermination service is large in order to effectively perform their function;d) that new emerging technology systems may use digital or other technologies that are more susceptible to interference from unwanted emissions from radar systems due to their high peak envelope power;e) that Radiocommunication Study Group 8 has been studying the question of efficient use of the radio spectrum by radar systems including the study of inherent unwanted emission characteristics of various types of output devices;f) that Radiocommunication Study Group 9 completed studies on the effects of unwanted emissions from radar systems on systems in the fixed service and developed Recommendations ITU-R F.1097 Interference Mitigation Options to Enhance Compatibility between Radar Systems and Digital Radio-Relay Systems and F.1190 Protection Criteria for Digital Radio-Relay Systems to Ensure Compatibility with Radar Systems in the Radiodetermination Service;g) that unwanted emissions from radar systems may in some cases cause unacceptable interference to systems in other radio services operating in the adjacent and harmonically related bands, especially when the technical and operational characteristics of the other radio service systems are changed in ways that make them more susceptible to interference;h) that performance (bandwidth, coherency, etc.), expected lifetime, cost, weight, size and mechanical ruggedness are important factors that must be considered in the design-to-performance specifications of radiodetermination systems;j) that Radiocommunication Study Group 1 revised Recommendation ITU-R SM.329 which includes spurious emission limits for the radiodetermination service;k) that WRC-2000 revised Appendix S3 Table of Maximum Permitted Spurious Emission Power Levels based on Recommendation ITU-R SM.329, and decided that radiodetermination service transmitters installed after 1 January 2003 and all transmitters after 1 January 2012 must comply with these power levels;

* This Question should be brought to the attention of Radiocommunication Study Groups 1 and 9, the International Maritime Organization (IMO), the International Civil Aviation Organization (ICAO), the International Maritime Radio Committee (CIRM), and the World Meteorological Organization (WMO).


- 44 -

l) that Study Group 8 developed Recommendation ITU-R M.1177 on Techniques for Measurement of Unwanted Emissions of Radar Systems;m) that Study Group 8 developed Recommendation ITU-R M.1314 on Reduction of Spurious Emissions of Radar Systems Operating in the 3 GHz and 5 GHz bands,

notingthat the out-of-band limits in bands allocated to the radiodetermination service on an exclusive basis are under the purview of Study Group 8,

decides that the following Question should be studied1 What are the unwanted emission levels from existing and state-of-the-art radar systems below 26 GHz taking into account:a) radar missions such as safety of life, radionavigation, surveillance, tracking, etc.;b) type and size of the platform (e.g. fixed, mobile, shipborne, airborne, etc.);c) available technologies; andd) economic considerations?2 What mitigation options, such as the choice of output device, could be taken into consideration in the design and implementation of radar systems to reduce radar spurious emissions, and what are their associated impacts on operational performance (bandwidth, coherency, etc.) expected lifetime, relative cost, weight, size and mechanical ruggedness?3 What unwanted emission levels can be achieved using these mitigation options, and what compatibility can then be achieved with other radio services?

further decides1 that the results of the above studies should be included in (a) Recommendation(s);2 that the above studies should be completed by the 2006 Radiocommunication Assembly.

__________


- 45 -

Part 2

Draft revision of Recommendation ITU-R M.589.2 on the "Technical characteristics of methods of data transmission and interference protection for radionavigation services in the frequency bands between 70 and 130 kHz" (ITU-R Document 8/14).


This ITU-R SG8 document is based on Document 8B/TEMP/5 produced by the October 2000 meeting of WP8B. This Recommendation is proposed to be expanded with material regarding data transmission from LORAN and Chavka stations to augment GNSS. This material includes protection criteria and signal level determination guidelines. Furthermore, material is proposed to be included on the technical characteristics of tri state pulse position modulation and message types and message formats. The GNSSP should provide the necessary information on the proposed amendments

AMCP WGF ACTION: Review GNSSP comments


- 46 -

Source: Document 8/14

Working Party 8B

DRAFT REVISION OF RECOMMENDATION ITU-R M.589-2*

TECHNICAL CHARACTERISTICS OF METHODS OF DATA TRANSMISSION AND INTERFERENCE PROTECTION FOR RADIONAVIGATION SERVICES IN THE

FREQUENCY BANDS BETWEEN 70 AND 130 kHz

(1982-1986-1992)SummaryA number of administrations are providing radionavigation services in the frequency band between 70 and 130 kHz. This Recommendation defines protection criteria to these radionavigation services and provides signal level determination guidelines.Furthermore, a number of administrations are implementing or considering implementing data transmissions from Loran-C and Chayka stations to augment Global Navigation Satellite Systems (GNSS). This Recommendation contains the technical characteristics to which tri-state pulse position modulation data transmissions should conform. The Recommendation also describes the message types and the message format associated with this method of data transmission.


consideringa) that radionavigation systems exist or are being implemented in the three Regions of the ITU;b) that various services, including radionavigation systems, operate in frequency bands between 70 and 130 kHz;c) that the operating characteristics of these radionavigation systems are well established and sufficiently documented by the appropriate service providers;d) that radionavigation being a safety service, all practical means consistent with the Radio Regulations (RR) should be taken to prevent harmful interference to any radionavigation system;

* The Director, CCIR, is requested to bring this Recommendation should be brought to the attention of the International Maritime Organization (IMO), the International Civil Aviation Organization (ICAO), the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) and Study Group 7.




Document 8/14(Rev.1)-E6 November 2000Original: English

- 47 -

e) that users of phased pulsed radionavigation systems in the band 90-110 kHz receive no protection outside that band, yet may receive benefit from their signals outside the occupied bandwidth;f) that in the band 90-110 kHz, different phased pulsed radionavigation systems may operate in adjacent areas, on the same assigned frequency and within the same occupied bandwidth;g) that Loran-C and Chayka systems are characterized by ground waves that follow the Earth's contours with ranges that exceed comparably powered medium frequency systems, and by sky waves that may be received at considerably greater distances;h) that Loran-C or Chayka provides an independent radionavigation system to complement GNSS;j) that GNSS components exist or are being implemented and the accuracy may not be enough for some specialized navigation, or for the position sensor in electronic chart systems;k) that safety applications require integrity information for position fixes derived from GNSS;l) that the accuracy and integrity of GNSS can be improved considerably by the transmission of differential corrections or other data;m) that appropriate modulation of Loran-C and Chayka transmissions enables these systems to transmit differential GNSS corrections, integrity messages and other data without interfering with the Loran-C or Chayka navigation function;n) that the transmission of differential GNSS corrections, integrity messages and other data may benefit from the long-range transmission characteristics of Loran-C or Chayka;o) that appropriate modulation of Loran-C and Chayka transmissions increases the efficiency of the use of the available bandwidth;p) that a number of administrations currently provide Loran-C or Chayka coverage of coastal waters and land areas enabling a worldwide standard for the transmission of differential GNSS corrections, integrity messages and other data to be introduced efficiently and economically;q) that other methods of data transmission using Loran-C or Chayka signals may be introduced,

recommends

1 that information be exchanged between the authorities operating radionavigation systems in the band 90-110 kHz with those operating other systems in the band 70-130 kHz employing stable transmissions;2 that administrations operating radionavigation systems in the band 90-110 kHz in adjacent areas coordinate the technical characteristics of their individual systems in accordance with the RR;3 that within the allocated band 90-110 kHz, the protection criteria for pulsed radionavigation systems (e.g. Loran-C and Chayka) should be in terms of unwanted to wanted emissions and in accordance with Annex 1;


- 48 -

4 that determination of Loran-C signal levels should be in accordance with the guidelines given in Annex 1;5 that any method of data transmission using Loran-C and Chayka signals should preserve the utility of the existing radionavigation services;6 that a data service using tri-state pulse position modulation of Loran-C or Chayka signals should be designed in accordance with the technical characteristics given in Annex 2.


- 49 -

ANNEX 1

Loran-C/Chayka protection criteria and signal level determination guidelines

1 Protection criteria1.1 The protection criteria for Loran-C/CW interference as a function of frequency offset are given in Fig 1.1.2 Near-synchronous interference at frequency, f, should satisfy the following relationship:

where:GRI : group reception intervals

n : any integer, andb : response bandwidth of the receiver (related to response time).

In the track-mode, typical Loran-C receivers have a –3 dB tracking response of 0.01 Hz for marine receivers and 0.1 Hz for aeronautical receivers. However, in the signal acquisition, or search mode, the response may be of considerably higher frequency. The value of b = 1.0 Hz is therefore recommended to be used.


- 50 -

0 5 1 0 1 5 2 0 2 5 3 0

– 3 0

– 2 0

– 1 0

0

1 0

2 0

3 0

D 01

Freq u en cy o ffse t fro m 1 0 0 kH z

Unw

ante

d-to

-wan

ted

signa

l rat

io (d

B)

N o n -sy n ch ro n o u s

N ea r-sy n ch ro n o u s

F IG U RE 1

L oran-C /C W I protection cr iter ia

1.3 The protection criteria for Loran-C/FSK interference as a function of frequency offset are given in Fig. 2.

2 Signal level determination guidelinesThe application of Figs. 1 and 2 to determine a maximum acceptable field strength of a specific unwanted signal to a known frequency requires knowledge of the expected Loran-C signal strength. This expected signal strength varies widely within the coverage area of a specific Loran-C chain. However, a minimum level may be determined at the coverage boundary.The area of Loran-C coverage is specified by the administration operating the stations within a chain. This chain coverage area is determined on the basis of the Loran-C signal strength with respect to expected ambient noise levels. The signal-to-noise ratio at the boundary of the coverage area is typically –10 dB. Therefore, the signal-to-noise ratio within the defined coverage area is greater than that value. The ambient noise levels used to calculate the boundaries are derived from Recommendation 372, characteristics and applications of atmospheric radio noise data. The Loran-C field strength, measured at the boundary of that coverage area, then represents the minimum expected. For example, if the expected noise level is 55 dB(µV/m), a Loran-C signal level of 45 dB(µV/m) or higher would likely be found throughout the coverage area. 45 dB(µV/m) could then be used as the value of the wanted signal in conjunction with Figs. 1 and 2.A study relative to chains operated within the United States of America reported that Loran-C signal levels within defined coverage areas may be as low as 43 dB(µV/m). Using this value, and considering a near-synchronous CWI signal between 90 and 110 kHz, the maximum unwanted to wanted signal level, determined from Fig. 1 is –20 dB. In this case, the unwanted field strength at the Loran-C receiver may have to be below 23 dB(µV/m) to prevent interference.


- 51 -

0 5 10 1 5 20 25 3 0

–3 0

–2 0

–1 0

0

1 0

2 0

3 0

D 0 2F req u en cy o ffs e t fro m 1 0 0 k H z

Unw

ante

d-to

-wan

ted

signa

l rat

io (d

B)

FIG U R E 2

L oran-C /F S K protec tion cr iter ia

ANNEX 2

Technical characteristics of a tri-state pulse position modulation (3s-PPM) data service using Loran-C and Chayka transmissions in the frequency band 90-110 kHz

1 StructureThe following structure is used for signal specification:

1 Physical layer Loran-C and Chayka signal specification

As documented by the appropriate service providers

2 Modulation/demodulation layer

Description of the 3s-PPM Chapter 2 of this Annex

3 FEC layer Description of the Forward Error Correction algorithm

Chapter 3 of this Annex

4 Message coding layer Description of the message coding algorithm

Chapter 4 of this Annex

2 Modulation/demodulation layer These definitions give the modulation of the Loran-C or the Chayka signal to enable data transmissions. The definitions include the low level modulation type, the modulation strategy to minimize devaluation of


- 52 -

Loran-C or Chayka use for positioning and the relation between modulation patterns and other data representations.


- 53 -

2.1 Pulse modulation

2.1.1 TimingA 3s-PPM should be applied to pulse three (3) to eight (8) of each pulse group. The modulation should consist of a time-shift of one (1) s of the pulse transmission, with respect to an unmodulated pulse. The three possible states of the modulation are given in Table 2-1.

TABLE 2-1

States of the modulation

Pulse state Transmission time minus time of

reference pulse (s)

Indication

Advanced pulse 1

Prompt pulse 0 0Delayed pulse +1 +

2.1.2 Modulation balanceThe number of advanced and delayed pulses of one channel in one pulse group should be equal. The modulation of six (6) pulses in one pulse group resolves in 141 possible balanced patterns, refer to Table 2-2, of which 128 should represent valid data, one (1) should indicate no data transmission and 12 should be not used.

TABLE 2-2

Modulation pattern combination

Modulation pattern combination Example Number of combinations

6 x zero (0) 0 x plus (+) 0 x minus () 0 0 0 0 0 0 14 x zero 1 x plus 1 x minus 0 0 + 0 - 0 302 x zero 2 x plus 2 x minus 0 + - + 0 - 900 x zero 3 x plus 3 x minus + + - - - + 20

Total = 141

2.1.3 Timing accuracyThe timing accuracy of the modulated signal should conform to the same timing accuracy requirements as for the unmodulated signal.

2.2 Modulation patterns

2.2.1 Pattern/data translationEach of the 128 valid modulation patterns should uniquely represent a 7 bit binary block of data as shown below.


- 54 -

Decimal Hexa- Patterndecimal



0 0 --00++ 43 2B 00-+-+ 86 56 ++-00-1 1 --0+0+ 44 2C 00-++- 87 57 ++0--02 2 --0++0 45 2D 00+--+ 88 58 ++0-0-3 3 --+00+ 46 2E 00+-+- 89 59 ++00--4 4 --+0+0 47 2F 00++-- 90 5A -0000+5 5 --++00 48 30 0+--0+ 91 5B -000+06 6 -0-0++ 49 31 0+--+0 92 5C -00+007 7 -0-+0+ 50 32 0+-0-+ 93 5D -0+0008 8 -0-++0 51 33 0+-0+- 94 5E -+00009 9 -00-++ 52 34 0+-+-0 95 5F 0-000+10 A -00+-+ 53 35 0+-+0- 96 60 0-00+011 B -00++- 54 36 0+0--+ 97 61 0-0+0012 C -0+-0+ 55 37 0+0-+- 98 62 0-+00013 D -0+-+0 56 38 0+0+-- 99 63 00-00+14 E -0+0-+ 57 39 0++--0 100 64 00-0+015 F -0+0+- 58 3A 0++-0- 101 65 00-+0016 10 -0++-0 59 3B 0++0-- 102 66 000-0+17 11 -0++0- 60 3C +--00+ 103 67 000-+018 12 -+-00+ 61 3D +--0+0 104 68 0000-+19 13 -+-0+0 62 3E +--+00 105 69 0000+-20 14 -+-+00 63 3F +-0-0+ 106 6A 000+-021 15 -+0-0+ 64 40 +-0-+0 107 6B 000+0-22 16 -+0-+0 65 41 +-00-+ 108 6C 00+-0023 17 -+00-+ 66 42 +-00+- 109 6D 00+0-024 18 -+00+- 67 43 +-0+-0 110 6E 00+00-25 19 -+0+-0 68 44 +-0+0- 111 6F 0+-00026 1A -+0+0- 69 45 +-+-00 112 70 0+0-0027 1B -++-00 70 46 +-+0-0 113 71 0+00-028 1C -++0-0 71 47 +-+00- 114 72 0+000-29 1D -++00- 72 48 +0--0+ 115 73 +-000030 1E 0--0++ 73 49 +0--+0 116 74 +0-00031 1F 0--+0+ 74 4A +0-0-+ 117 75 +00-0032 20 0--++0 75 4B +0-0+- 118 76 +000-033 21 0-0-++ 76 4C +0-+-0 119 77 +-+-+-34 22 0-0+-+ 77 4D +0-+0- 120 78 -+-+-+35 23 0-0++- 78 4E +00--+ 121 79 +-+--+36 24 0-+-0+ 79 4F +00-+- 122 7A -+-++-37 25 0-+-+0 80 50 +00+-- 123 7B +--+-+38 26 0-+0-+ 81 51 +0+--0 124 7C -++-+-39 27 0-+0+- 82 52 +0+-0- 125 7D +--++-40 28 0-++-0 83 53 +0+0-- 126 7E -++--+41 29 0-++0- 84 54 ++--00 127 7F +0000-42 2A 00--++ 85 55 ++-0-0


- 55 -

2.2.2 "No data transmission" patternThe pattern "000000" should be used to indicate that no data is being transmitted.

2.2 Message structureOne (1) 3s-PPM message should consist of thirty (30) consecutive pulse groups.

2.3 BlankingA blanked pulse group should be considered to have been transmitted for modulation purposes.

3 Forward Error Correction layerA systematic Reed-Solomon (30,10) 27-ary code should be applied to all messages. All messages should consist of 30 symbols, each symbol representing a 7 bit element. Of these symbols, 10 should be data and 20 should be Reed-Solomon parity.

3.1 Primitive polynomialThe symbols should be elements of the Galois field GF(128), constructed using the primitive polynomial:

.The relationship between GF(128) elements and binary data should be to consider the value of the power of alpha as a 7 bit binary value converted to decimal. The symbol "0" should correspond to a 7 bit value of 127.

3.2 Generator polynomialThe FEC parity should be defined by the following generator polynomial:

.

The relation between a symbol representation and a polynomial is given in Table 3-1.

TABLE 3-1

Relation between symbol representation andpolynomial representation

Position Symbol number

Multiply with

Least significant symbol S1 x0

S2 x1

… …… …

Most significant symbol Sn xn-1


- 56 -

The following steps should be used in the message encoding process:1) translation of the binary data to a symbol representation, using the primitive polynomial;2) translation of the symbol representation obtained in step 1 to a polynomial;3) multiplication of the polynomial obtained in step 2 with x20;4) division of the polynomial obtained in step 3 by the generator polynomial;5) summation of the polynomial obtained in step 3 with the remainder of the division in

step 4;6) translation of the polynomial obtained in step 5 to a symbol or binary representation.

3.3 Order of transmissionThe first transmitted pattern of an FEC-encoded message should correspond to the least significant symbol of that message.

3.4 Continuity of modulationMessages should be transmitted consecutively without interleaving. The pattern transmitted in the first pulse group after the last pattern of a message shall be the first pattern of the next message.

4 Message coding layer4.1 Generic structure

All message types should be defined with the same structure, consisting of a Message Type, a Message body, and a Cyclic Redundancy Check (CRC). The Message Type should identify the type of data contained in the Message body. The generic structure is given in Table 4-1.

TABLE 4-1

Generic structure of data section

Field Bits used Bit numbers

Message Type 4 I1 – I4

Message body 52 I5 – I56

CRC 14 I57 – I70

Total 704.2 Message Type Identification

The Message Type should be in accordance with the information presented in Table 4-2.


- 57 -

TABLE 4-2

Interpretation of Message Type

Indication Message Type Decimal

I4 I3 I2 I1

Type 1 DGPS Corrections 0 0 0 1 1Type 2 DGLONASS

Corrections0 0 1 0 2

Type 3 Reserved 0 0 1 1 3Type 4 Reserved 0 1 0 0 4Type 5 Text Message 0 1 0 1 5Type 6 Reserved 0 1 1 0 6Type 7 Reserved 0 1 1 1 7Type 8 Reserved 1 0 0 0 8Type 9 Reserved 1 0 0 1 9Type 10 Reserved 1 0 1 0 10Type 11 Reserved 1 0 1 1 11Type 12 Reserved 1 1 0 0 12Type 13 Reserved 1 1 0 1 13Type 14 Reserved 1 1 1 0 14Type 15 Reserved 1 1 1 1 15Type 16 Reserved 0 0 0 0 0


- 58 -

4.3 Message bodiesTABLE 4-3a

Message bit assignment tableMessage Type

Bit Num. 1 2 3 4 5 6 7 81

0001 0010 0011 0100 0101 0110 0111 10002345

Modified

Z-Count

13 bits

Modified

Z-Count

13 bits

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

Sequence Number

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

678 End9 Text

ASCII with Cyrillic

extensions

6 wordsby

8 bitsper

word

101112131415161718 Scale Scale19 UDRE UDRE2021

SatellitePRN

SatellitePRN

2223242526

P

R

C

15 bits

P

R

C

15 bits

272829303132333435363738394041

R

R

C

8 bits

R

R

C

8 bits

4243444546474849 I

O

Change50 T

O5152


- 59 -

D

8 bitsD

7 bits

53545556

57-70 CRC CRC CRC CRC CRC CRC CRC CRCTABLE 4-3b

Message bit assignment tableMessage Type

Bit Num. 9 10 11 12 13 14 15 161

1001 1010 1011 1100 1101 1110 1111 00002345

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

R

e

s

e

r

v

e

d

6789

101112131415161718192021222324252627282930313233343536373839404142434445464748


- 60 -

4950515253545556

57-70 CRC CRC CRC CRC CRC CRC CRC CRC


- 61 -

4.4 Definitions

4.4.1 "Modified" Z-countThe Z-count represents the reference time for the differential data messages. The Z-count begins at 0, at the beginning of each hour in GPS or GLONASS time and ranges to a maximum value of 3 599.4 s, with a resolution of 0.6 s. It is used to compute the GPS time or GLONASS time of the corrections, in the same manner as other time calculations are made in the user's receivers.

4.4.2 Scale factorTwo states of the scale factor for pseudorange corrections may be used and these are defined in Table 4-4. The rationale for the two-level scale factor is to maintain a high degree of precision most of the time, and the ability to increase the range of the corrections on those rare occasions when it is needed.

TABLE 4-4

Scale factor

Code No. Indication

0 (0) Scale factor for pseudorange correction is 0.02 m and for range rate correction is 0.002 m/s

1 (1) Scale factor for pseudorange correction is 0.32 m and for range rate correction is 0.032 m/s

4.4.3 User differential range error (UDRE)An estimate of the root-mean-square error in the differential pseudorange correction. It is influenced by such factors as satellite signal-to-noise ratio, multipath effects and data smoothing. Table 4-5 defines the format for the UDRE field.

TABLE 4-5

User differential range error (UDRE)

4.4.4 Satellite IDStandard format (1-32, 32 is indicated with all zeros).


Code No.1 differential error

(m)00 (0) 101 (1) 1 and 410 (2) 4 and 811 (3) Reference station not useable

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4.4.5 Pseudorange Correction (PRC)The pseudorange correction describes the estimated correction at the time of measurement in the reference receiver. The relationship between pseudorange correction, range rate correction and reference time is defined by the following equation:

.

The pseudorange correction is given as a 2's complement value. The resolution depends on the scale factor.

4.4.6 Range-rate Correction (RRC)The range rate correction describes the estimate of the rate of change of the pseudorange correction at the time of measurement in the reference receiver. The use of the range rate correction is described by the previous equation. The resolution depends on the scale factor.

4.4.7 Issue of data (IOD)The issue of data (IOD) as broadcast by the reference station is the value in the GPS navigational messages which corresponds to the GPS ephemeris data used to compute corrections. This is a key to ensure that the user equipment calculations and reference station corrections are based on the same set of broadcast orbital and clock parameters.

4.4.8 Tb of navigation data (TOD)The time within the current 24 h period by UTC(SU), which includes the operational information transmitted in the frame.

4.4.9 Sequence NumberThe Message Number should be equal for all portions of one text message. The Message Number should increase with unit step for subsequent text messages, restarting at "000" after "111".

4.4.10 End of Message (End)The End-of-Message indicates the last portion of a text message. A value of "0" should indicate that more portions are required to complete the text message. A value of "1" should indicate completion of the text message.

4.4.11 Text charactersUp to six (6) characters of eight (8) bits each are accommodated in each portion of a text message. Codes from 0-127 should correspond to standard ASCII codes. Cyrillic characters should be represented by codes greater than 127.

4.5 Cyclic Redundancy Check (CRC)The cyclic redundancy check should be generated using the following polynomial:

.

The following steps should be used in the calculation of the cyclic redundancy check:1) translation of the data, including the Message Type field to a polynomial following the

convention defined in Table 6. The resulting polynomial will not contain higher orders of x than x55;


- 63 -

2) multiplication of the polynomial obtained in step 1 with x14;3) division of the polynomial obtained in step 2 by the generator polynomial;4) translation of the remainder of the division in step 3 to a binary representation is the

CRC.

TABLE 4-6

Relation between binary representation andpolynomial representation

Position Bit number Multiply with

LSB I1 x0

I 2 x1

… …… …

MSB In xn-1

_______________


- 64 -

Part 3

Preparations for WRC-03 (Attachment 11 to ITU-R Document 8B/49-E - Report of the eighth meeting of Working Party 8B)


This paper is based on on Document 8B/TEMP/6, produced by the October 2000 meeting of WP8B. It provides a work plan for WP 8B on ITU-R preparatory work in which Working Party 8B is responsible.

This work plan includes:

1 Items for which WP 8B is primary responsible.

a. WRC-2003 agenda item 1.4 "to consider the results of studies related to Resolution 114 (WRC-95), dealing with the use of the band 5091 - 5150 MHz by the fixed satellite service (Earth-to-space) (limited to non-GSO MSS feeder links), and to review the allocation to the aeronautical radionavigation service and the fixed satellite service in the band 5091 - 5150 MHz."

In ICAO, work on this agenda item has been initiated by AMCP WG F, in collaboration with the European Frequency Management Group (FIG). A preliminary ICAO position on this agenda item has been developed and further work is ongoing. Results have to be presented to ITU-R in a timely manner.

b. WRC-2003 agenda item 1.14 "to consider measures to address harmful interference in the band allocated to the maritime mobile and aeronautical mobile (R) services, taking into account Resolutions 207 and 350, and to review the frequency and channel arrangements in the maritime MF and HF bands concerning the use of new digital technology, also taking into account Resolution 347."

In ICAO, work on this agenda item has been initiated by AMCP WG F. Only Resolution 207 is relevant to the AM(R)S. An initial ICAO position on this agenda item has been developed and further work is ongoing.

c. WRC-2003 agenda item 4 "in accordance with Resolution 95, to review the resolutions and recommendations of previous conferences with a view to their possible revision, replacement or abrogation."

This agenda item of the WRC requires primarily further consideration by AMCP WG F. Work on this subject will be initiated at the WG F meeting planned for March/April 2001.

AMCP WG ACTION: initiated review of resolutions/recommendations

2. Items for which WP 8B is contributing (to other WP's) or interested.

a. WRC-2003 agenda item 1.24 "to review the usage of the band 13.75 - 14 GHz, in accordance with resolution 733, with a view to addressing the sharing conditions"

On this agenda item an ICAO position has been drafted and further review of it is unlikely.

b. WRC-2003 agenda item 1.5 "to consider, in accordance with resolution 736, regulatory provisions and spectrum requirements for new and additional allocations to the mobile, fixed, Earth


- 65 -

exploration satellite and space research services, and to review the status of the radiolocation service in the frequency range 5150 - 5725 MHz, with a view to upgrading it, taking into account the results of ITU studies."

On this agenda item an ICAO position has been drafted and further review of it is unlikely. Developments on the work on this agenda item needs to be followed carefully in order to preserve the future use of the band 5360 - 5470 MHz by the aeronautical radionavigation service.

c. WRC-2003 agenda item 1.8 "to consider issues related to unwanted emissions"

On this agenda item an ICAO position has been drafted. However, in the light of further developments in ITU-R, further refinement of this position may be required in order to avoid unduly constraints to the aeronautical mobile and radionavigation services.

d. WRC-2003 agenda item 1.15 "to review the results of studies concerning the radionavigation satellite service in accordance with resolutions 604, 605 and 606."

This agenda item refers to the introduction of allocations to the radionavigation satellite service in various frequency bands. The involvement of 8B mainly relates to the need to protect existing use of the bands around 1 GHz for TACAN/DME and radar systems.

e. WRC-2003 agenda item 1.31 "to consider additional allocations to the mobile satellite service in the 1-3 GHz band, in accordance with resolutions 226 and 227."

On this agenda item an ICAO position has been drafted and further review of it is unlikely.

AMCP WGF ACTION: Note


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ATTACHMENT 11(Source: Document 8B/TEMP/6)

PREPARATIONS FOR WRC-03

WP 8B created an electronic correspondence group to progress the work of CPM and WRC-03 preparations in the interim between meetings. Ms Darlene Drazenovich was nominated as the Rapporteur for this group.The WRC-03 agenda items assigned to WP 8B as the responsible group and contributing/interested group are detailed in Annexes 1 and 2 respectively. WP 8B will contribute to the work of the Special Committee on Regulatory/Procedural matters, as appropriate, and as it pertains to WRC-03 agenda item 1.4 specifically and any other agenda item that WP 8B deems to have regulatory and procedural implications per Annex 3. A work plan to prepare for WRC-03 to include deliverables and a timeline for WP 8B completion of the deliverables is contained in Annex 4. Administrations and members are requested to submit contributions to next meeting of WP 8B to advance the studies required for WRC-03.

Annexes: 4


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ANNEX 1

(to Attachment 11)

Allocations of ITU-R preparatory work for the 2003 World Radiocommunication Conference

WP 8B as Responsible Group

Topic Responsible Group*

Action to be taken by the ITU-R Study Group

1.4 to consider the results of studies related to Resolution 114 (WRC-95), dealing with the use of the band 5 091-5 150 MHz by the fixed-satellite service (Earth-to-space) (limited to non-GSO MSS feeder links), and review the allocations to the aeronautical radionavigation service and the fixed-satellite service in the band 5 091-5 150Resolution 114 (WRC-95)Use of the band 5 091-5 150 MHz by the fixed-satellite service (Earth-to-space) (limited to feeder links of the non-geostationary mobile-satellite service)

SG 8

(WP 8B)

1 to study the technical and operational issues relating to sharing of this band between the aeronautical radionavigation service and the fixed-satellite service providing feeder links of the non-GSO mobile-satellite service (Earth-to-space);2 to bring the results of these studies to the attention of WRC-01,

1.9 to consider Appendix S13 and Resolution 331 (Rev.WRC-97) with a view to their deletion and, if appropriate, to consider related changes to Chapter SVII and other provisions of the Radio Regulations, as necessary, taking into account the continued transition to and introduction of the Global Maritime Distress and Safety System (GMDSS);Resolution 331 (Rev.WRC-97)Transition to the Global Maritime Distress and Safety System (GMDSS) and continuation of the distress and safety provisions in Appendix S13

SG 8(WP 8B)

invites the Radiocommunication Study Group 8to review the operational and procedural incompatibilities between the old and new systems with a view to presenting the information to WRC-01.

1.10 to consider the results of studies, and take necessary actions, relating to:1.10.1 exhaustion of the maritime mobile service identity numbering resource (Resolution 344 (WRC-97));Resolution 344 (WRC-97)

Exhaustion of the maritime mobile service identity numbering resource

SG 8

(WP 8B)

1 to keep under review the Recommendations for assigning MMSIs, with a view to identifying alternative resources before the resources are exhausted;2 to consult each other when addressing changes to any of the Recommendations affecting the MMSI numbering resources; 3 to complete studies on an urgent basis when a future world radiocommunication conference identifies the impending exhaustion of the MMSI resource,

1.10.2 shore-to-ship distress communication priorities (Resolution 348 (WRC-97));

* All appropriate regulatory/procedural studies on relevant agenda items will be carried out by the Special Committee on Regulatory/Procedural matters (SC) on the basis of proposals from membership of ITU and the relevant ITU-R Study Group/Working Party/Task Group.


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Resolution 348 (WRC-97)Studies required to provide priority to distress communications originated by shore-based search and rescue authorities

SG 8(WP 8B)

recognizinga) that life and property may be lost if rapid access is not provided for distress related communications originated by the rescue authority;b) that the International Maritime Organization (IMO) has considered this problem and decided that provisions are necessary for giving priority to shore-originated distress communications;c) that Inmarsat is currently studying how to provide such priority communications,

resolves to invite1 ITU-R to monitor the status of these studies and to develop suitable Recommendations;

1.14 to consider measures to address harmful interference in the bands allocated to the maritime mobile and aeronautical mobile (R) services, taking into account Resolutions 207 (Rev.WRC-2000) and 350 [COM5/12] (WRC-2000), and to review the frequency and channel arrangements in the maritime MF and HF bands concerning the use of new digital technology, also taking into account Resolution 347 (WRC-97);Resolution 207 (Rev.WRC-2000) Measures to address unauthorized use of and interference to frequencies in the bands allocated to the maritime mobile service and to the aeronautical mobile (R) service

SG 8(WP 8B)

1 to study possible technical and regulatory solutions to assist in the mitigation of interference to operational distress and safety communications in the maritime mobile service and aeronautical mobile (R) service;2 to increase regional awareness of appropriate practices in order to help mitigate interference in the HF bands, especially on distress and safety channels;3 to report the results of the above studies to the next competent conference,

Resolution 350 [COM5/12] (WRC-2000)Study on interference caused to the distress and safety frequencies 12 290 kHz and 16 420 kHz by routine calling

SG 8(WP 8B)

1 to invite ITU-R to study the interference to the distress and safety frequencies 12 290 kHz and 16 420 kHz caused by routine calling on channels 1221 and 1621;2 to instruct the Radiocommunication Bureau, in consultation with administrations, to organize monitoring programmes for the support of these studies;3 to urge administrations to participate actively in these studies;4 to invite ITU-R to complete these studies in time for consideration by WRC5 to invite WRC-03 to consider this issue,

Resolution 347 (WRC-97)Use of digital telecommunication technologies in the MF and HF bands by the maritime mobile service

To be noted.

1.17 to consider upgrading the allocation to the radiolocation service in the frequency range 2 900-3 100 MHz to primary;SG 8(WP 8B)

to complete the studies on technical and operational issues related to the upgrading of the radiolocation service allocation taking into account Nos. S5.425, S5.426 and S5.427

1.28 to permit the use of the band 108-117.975 MHz for the transmission of radionavigation satellite differential correction signals by ICAO standard ground-based systems;


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SG 8(WP 8B)

to undertake studies for consideration by WRC-03, relating to technical and operational issues relating to the use of 108-177.975 MHz for the transmission of radionavigation-satellite differential corrections by ICAO standard ground-based systems

4 in accordance with Resolution 95 (Rev.WRC-2000), to review the resolutions and recommendations of previous conferences with a view to their possible revision, replacement or abrogation;Resolution 95 (Rev.WRC-2000)General review of the resolutions and recommendations of world administrative radio conferences and world radiocommunication conferences

instructs the Director of the Radiocommunication Bureau1 to conduct a general review of the resolutions and recommendations of previous conferences and, after consultation with the Radiocommunication Advisory Group and the chairpersons and vice-chairpersons of the radiocommunication study groups, submit a report to the second session of the Conference Preparatory Meeting in respect of 2 if practicable, to include in the above report an indication of the agenda item, if appropriate, and possible responsible committees within the conference for each text, based on the available information as to the possible structure of the conference,

invites the Conference Preparatory Meetingto include, in its report, the results of a general review of the resolutions and recommendations of previous conferences.

Contributing Group (bolded) shall submit the contribution.Interested Group (not bolded) may submit the contribution.


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ANNEX 2(to Attachment 11)

Allocations of ITU-R preparatory work for the 2003 World Radiocommunication Conference WP 8B as Contributing/Interested Group

Topic Responsible Group*

Action to be taken by the ITU-R Study Group

1.24 to review the usage of the band 13.75-14 GHz, in accordance with Resolution 733 [COM5/10] (WRC-2000), with a view to addressing sharing conditions;Resolution 733 [COM 5/10] (WRC-2000)Review of sharing conditions between services in the band 13.75-14 GHz

JTG 4-7-81 to conduct studies, as a matter of urgency and in time for consideration by WRC-03, on the sharing conditions indicated in Nos. S5.502 and S5.503reviewing the constraints in No. S5.502 regarding the minimum antenna diameter of GSO FSS earth stations and the constraints on the e.i.r.p. of the radiolocation service;2 to identify and study, in time for consideration by WRC-03, possible alternative sharing conditions to those indicated in Nos. S5.502 and S5.503.

1.5 to consider, in accordance with Resolution 736 [GT PLEN-2/1] (WRC-2000), regulatory provisions and spectrum requirements for new and additional allocations to the mobile, fixed, Earth exploration-satellite and space research services, and to review the status of the radiolocation service in the frequency range 5 150-5 725 MHz, with a view to upgrading it, taking into account the results of ITU-R studies;Resolution 736 [GT PLEN-2/1] (WRC-2000)Consideration by a future competent world radiocommunication conference of issues dealing with allocations to the mobile, fixed, radiolocation, Earth exploration-satellite (active), and space research (active) services in the frequency range 5 150-5 725 MHz

JTG4-7-8-9

resolvesthat, on proposals from administrations and taking into account the results of studies in ITU-R and the Conference Preparatory Meeting, [WRC-03] should consider:

1 allocation of frequencies to the mobile service in the bands 5 150-5 3505 470-5 725 MHz for the implementation of wireless access systems including RLANs;2 a possible allocation in Region 3 to the fixed service in the band 5 250-5 350 MHz, while fully protecting the worldwide Earth exploration-satellite (active) and space research (active) services;3 additional primary allocations for the Earth exploration-satellite service (active) and space research service (active) in the frequency range 5 460-5 570 MHz;4 review, with a view to upgrading, of the status of frequency allocations to the radiolocation service in the frequency range 5 350-5 650 MHz,

invites ITU-Rto conduct, and complete in time for [WRC-03], the appropriate studies leading to technical and operational recommendations to facilitate sharing between the services referred to in the resolves and existing services.

1.8 to consider issues related to unwanted emissions:1.8.1 consideration of the results of studies regarding the boundary between spurious and out-of-band emissions, with a view to including the boundary in Appendix Recommendation 66 (Rev.WRC-2000)Studies of the maximum permitted levels of unwanted emissions

SG 1(TG 1/5)

4 study the reasonable boundary of spurious emissions and out-of-band emissions with a view to defining such a boundary in Article S1;

1.8.2 consideration of the results of studies, and proposal of any regulatory measures regarding the protection of passive services from unwanted emissions, in particular from space service transmissions, in response to recommends 5 and 6 of Recommendation 66 (Rev.WRC-2000);Recommendation 66 (Rev.WRC-2000)Studies of the maximum permitted levels of unwanted emissions

SG 1

(TG 1/5)

5 study those frequency bands and instances where, for technical or operational reasons, more stringent spurious emission limits than the general limits in Appendix be required to protect safety services and passive services such as radio astronomy, and the impact on all concerned services of implementing or not implementing such limits;6 study those frequency bands and instances where, for technical or operational reasons, out-of-band limits may be required to protect safety services and passive services such as radio astronomy, and the impact on all concerned services of implementing or not implementing such limits;8 report the results of these studies to a competent world radiocommunication

* All appropriate regulatory/procedural studies on relevant agenda items will be carried out by the Special Committee on Regulatory/Procedural matters (SC) on the basis of proposals from membership of the ITU and the relevant ITU-R Study Group/Working Party/Task Group.


- 71 -

conference(s).1.12 to consider allocations and regulatory issues related to the space science services in accordance with Resolution 723 (Rev.WRC-2000) and to review all Earth exploration-satellite service and space research service allocations between 35 and 38 GHz, taking into account Resolution 730 [COM5/1] (WRC-2000);Resolution 723 (Rev.WRC-2000)Consideration by a future competent world radiocommunication conference of issues dealing with allocations to science services

SG 7(WP 7E)

resolvesto recommend that WRC-03 consider the following matters:1 provision of up to 3 MHz of frequency spectrum for the implementation of telecommand links in the space research and space operations services in the frequency range 100 MHz to 1 GHz;2 to consider incorporating in the Table of Frequency Allocations the existing primary allocation to the space research service in the band 7 145-7 235 MHz under No. S5.460;3 to review the allocations to the space research service (deep space) (space-to-Earth) and the inter-satellite service, taking into account the coexistence of these two services in the frequency range 32-32.3 GHz, with a view to facilitating satisfactory operation of these services;4 to review existing allocations to space science services near 15 GHz and 26 GHz, with a view to accommodating wideband space-to-Earth space research applications,

invites ITU-Rto complete the necessary studies, as a matter of urgency, taking into account the present use of allocated bands, with a view to presenting, at the appropriate time, the technical information likely to be required as a basis for the work of the conference,


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Resolution 730 [COM5/1] (WRC-2000)Use of the frequency band 35.5-35.6 GHz by spaceborne precipitation radars

SG 7(WP 7E)

1 to invite ITU-R to study sharing between spaceborne precipitation radars and other services in the band 35.5-35.6 GHz;2 to recommend that WRC-03 review the results of those studies and consider the removal of the restriction currently contained in No. S5.551A on spaceborne precipitation radars operating in the Earth exploration-satellite service in the band 35.5-35.6 GHz.

1.13 to consider regulatory provisions and possible identification of existing frequency allocations for services which may be used by high altitude platform stations, taking into account NoS5.5RRR and the results of the ITU-R studies conducted in accordance with Resolutions 122 (Rev.WRC-2000) and 734 [COM5/14] (WRC-2000);Resolution 734 [COM5/14] (WRC-2000)Feasibility of use by high altitude platform stations in the fixed and mobile services in the frequency bands above 3 GHz allocated exclusively for terrestrial radiocommunication

SG 9(WP 9B)

to carry out, as a matter of urgency, regulatory and technical studies to determine the feasibility of facilitating systems using HAPS in the fixed and mobile services in bands above 3 GHz allocated exclusively by the Table of Frequency Allocations or by footnotes for terrestrial radiocommunication, taking account of existing use and future requirements in these bands, and any impact on allocations in adjacent bands,

1.15 to review the results of studies concerning the radionavigation-satellite service in accordance with Resolutions 604 [COM5/16] (WRC-2000), [COM5/20] (WRC-2000);Resolution 604 [COM5/16] (WRC-2000)Studies on compatibility between the radionavigation-satellite service (space-to-Earth) operating in the frequency band 5 010-5 030 MHz and the radio astronomy service operating in the band 4 990-5 000 MHz

SG 8

(WP 8D)

1 to conduct, or continue to conduct, as a matter of urgency and in time for consideration by WRC-03, the appropriate technical, operational and regulatory studies to review the provisional pfd limit concerning the operation of space stations, including the development of a methodology for calculating the aggregate power levels in order to ensure that the RNSS (space-to-Earth) in the band 5 010-5 030 MHz will not cause interference detrimental to the RAS in the band 4 990-5 000 MHz;2 to report to CPM-02 on the conclusions of these studies,

Resolution 605 [COM5/19] (WRC-2000)Use of the frequency band 1 164-1 215 MHz by systems of the radionavigation-satellite service (space-to-Earth)

SG 8(WP 8D)

to conduct, as a matter of urgency and in time for WRC-03, the appropriate technical, operational and regulatory studies on the overall compatibility between the radionavigation-satellite service and the aeronautical radionavigation service in the band 960including an assessment of the need for an aggregate power flux-density limit, and revision, if necessary, of the provisional pfd limit given in No. S5.328A concerning the operation of radionavigation-satellite service (space-to-Earth) systems in the frequency band 1 164-1 215 MHz,

Resolution 606 [COM5/20] (WRC-2000)Use of the frequency band 1 215-1 300 MHz by systems of the radionavigation-satellite service (space-to-Earth)

SG 8(WP 8D)

to conduct, as a matter of urgency and in time for WRC-03, the appropriate technical, operational and regulatory studies, including an assessment of the need for a power flux-density limit concerning the operation of radionavigation-satellite service (space-to-Earth) systems in the frequency band 1 215-1 300 MHz in order to ensure that the radionavigation-satellite service (space-to-Earth) will not cause harmful interference to the radionavigation and the radiolocation services,

1.31 to consider the additional allocations to the mobile-satellite service in the 1-3 GHz band, in accordance with Resolutions 226 [COM5/29] (WRC


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Resolution 226 [COM5/29] Sharing studies for, and possible additional allocations to, the mobile-satellite service (space-to-Earth) in the 1-3 GHz range, including consideration of the band 1 518-1 525 MHz

SG 8(WP 8D)

1 to study, as a matter of urgency, sharing between the MSS and aeronautical mobile telemetry in all the Regions in the band 1 518-1 525 MHz, taking into account, Recommendation ITU-R M.1459;2 to review, as a matter of urgency, the pfd levels used as coordination thresholds for MSS (space-to-Earth) with respect to the protection of point-to-multipoint fixed-service systems in the band 1 518-1 525 MHz in Regions 1 and 3, taking into account the work already done in Recommendations ITU-R M.1141 and ITU-R M.1142 and the characteristics of fixed-service systems contained in Recommendations ITU-R F.755-2 and ITU-R F.758-1, and the sharing methodologies contained in Recommendations ITU-R F.758-1, ITU-R F.1107 and ITU-R F.1108;3 in the event that the studies of the specific frequency bands referred to in this resolution lead to an unsatisfactory conclusion, to carry out sharing studies in order to recommend alternative MSS (space-to-Earth) frequency bands in the 1-3 GHz range, but excluding the band 1 559-1 610 MHz, for consideration at WRC-03;4 to bring the results of these studies to the attention of WRC-03,

Resolution 227 [COM5/30]Sharing studies for, and possible additional allocations to, the mobile-satellite service (Earth-to-space) in the 1-3 GHz range, including consideration of the band 1 683-1 690 MHz

SG 8(WP 8D)

1 to complete, as a matter of urgency and in time for WRC-03, the technical and operational studies on the feasibility of sharing between MSS and MetSat, by determining appropriate separation distances between mobile earth stations and MetSat stations, including GVAR/S-VISSR stations, in the band 1 683-1 690 MHz, as stated in Recommendation ITU-R SA.1158-2;2 to assess, with the participation of WMO, the current and future spectrum requirements of the MetAids service, taking into account improved characteristics, and of the MetSat service in the band 1 683-1 690 MHz, taking into account future developments;3 in the event that the studies of the specific frequency band referred to in this resolution lead to an unsatisfactory conclusion, to carry out sharing studies in order to recommend alternative MSS (Earth-to-space) frequency bands in the 1-3 GHz range, but excluding the band 1 559-1 610 MHz, for consideration at WRC-03;4 to bring the results of these studies to the attention of WRC-03,

8 to recommend to the Council that additional budgetary and conference resources be provided so that the following items can be included in this agenda for WRC-03:

8.1 to examine the adequacy of the frequency allocations for HF broadcasting from about 4 MHz to 10 MHz, taking into account the seasonal planning procedures adopted by WRC-97;SG 6(WP 6E)


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ANNEX 3

(to Attachment 11)

Organization of the work of the Special Committee on Regulatory/Procedural matters

Pursuant to Resolution ITU-R 38-2 the CPM invites the Special Committee on Regulatory/Procedural Matters (SC) to focus its work, in particular, on the following topics, for which the CPM has noted that four Rapporteur Groups will be created. This does not preclude that the SC may establish other Rapporteur Groups or to address other issues of a regulatory/procedural nature as necessary.

SC-1 Mr Jean [email protected]

Regulatory/procedural aspects relating to Appendices S30, S30A and unplanned BSS in the framework of WRC-03 agenda items 1.27 and 1.34

SC-2 Mr Edward DAVISON [email protected]

Regulatory/procedural aspects relating to the fixed-satellite service in the framework of WRC-03 agenda items 1.19, 1.25, 1.26, 1.29. 1.30, 1.32 and 7.1

SC-3 Mr Srinivasan [email protected]

Regulatory/procedural aspects relating to space science services and to sharing issues in the 5 GHz band in the framework of WRC-03 agenda items 1.4, 1.5, 1.6 and 1.12

SC-4Mr Katsuhiko [email protected]

Regulatory/procedural aspects relating to high altitude platform stations in the framework of WRC-03 agenda items 1.13 and 1.33


mailto:[email protected]




- 75 -

ANNEX 4

(to Attachment 11)

Work programme

Agenda item Deliverables Timeline

1.4 DNR technical and operational characteristics of systems in the aeronautical radionavigation service in the band 5 091-5 150 MHz

October 2001

1.4 DNR on sharing between systems in the aeronautical radionavigation service and non-GSO feeder links in the mobile satellite service in the band 5 091-5 150 MHz

October 2001

1.9 Report on the operational and procedural incompatibilities between the old and new systems

October 2001

1.9 Modification to Chapter SVII as a result of consequential suppression of Appendix S13

October 2001

1.10.1 Revision to Recommendation ITU-R M.585-2 Assignment and use of MMSIs, with a view to identifying alternative resources before the resources are exhausted

October 2001

1.10.2 PDNR or report on priority for shore-originated distress communications

October 2001

1.14 PDNR or report on technical and regulatory solutions to assist in the mitigation of interference to operational distress and safety communications in the maritime mobile service and aeronautical mobile (R) service

October 2001

1.14 Report on increasing regional awareness of appropriate practices in order to help mitigate interference in the HF bands, especially on distress and safety channels

October 2001

1.14 Develop a monitoring programme in consultation with the BR for the support of studies on the interference to the distress and safety frequencies 12 290 kHz and 16 420 kHz caused by routine calling on channels 1221 and 1621

Completed*

1.14 Report on the interference to the distress and safety frequencies 12 290 kHz and 16 420 kHz caused by routine calling on channels 1221 and 1621

October 2001

1.17 PDNR on sharing, technical and operational issues between radars in the radiolocation and radionavigation services (taking into account Nos. S5.425, S5.426 and S5.427)

October 2001

1.241 Report on usage in the band 13.75-14 GHz October 2001


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1.24 Liaison statement to JTG 4-7-8 October 2000

1.241 DNR on technical and operational characteristics of radars in the 13.75-14 GHz band

May 2001**


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1.28 Report on technical and operational issues relating to the use of 108-117.975 MHz for the transmission of radionavigation-satellite differential corrections by ICAO standard ground-based systems

October 2001

1.5 Liaison statement to JTG 4-7-8-9 October 2000

1.52 PDNR for operational and technical characteristics of radars in the radiolocation service in the frequency range 5 350-5 650 MHz

May 2001

1.83 study the reasonable boundary of spurious emissions and out-of-band emissions with a view to defining such a boundary in Article S1

October 2001

1.83 study those frequency bands and instances where, for technical or operational reasons, more stringent spurious emission limits than the general limits in Appendix S3 may be required to protect safety services, and the impact on all concerned services of implementing or not implementing such limits;study those frequency bands and instances where, for technical or operational reasons, out-of-band limits may be required to protect safety services, and the impact on all concerned services of implementing or not implementing such limits

October 2001

1 WP 8B contributes to Responsible Group JTG 4-7-8.2 WP 8B contributes to Responsible Group JTG 4-7-8-9.3 WP 8B contributes to Responsible Groups SG 1 and TG 1/5. BR issued Circular Letter CR147 (see http://www.itu.int/itudoc/itu-r/cl/cr/index.html . Administrations are requested to take note of and participate in this monitoring programme as it will support WRC-03 activities. WP 8B requests contributions regarding this PDNR be submitted to the ITU-R no later than April 2001 in order for administrations to review prior to the May 2001 WP 8B meeting.


http://www.itu.int/itudoc/itu-r/cl/cr/index.html

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Part 4

Liaison statement to WP 1A on a "Study of interference from short-range radio devices using ultra wideband (UWB) technology operating in the 1 - 6 GHz bands (ITU-R Document 1A/28-E).

ICAO Secretariat comments

This paper is based on on Document 8B/TEMP/9, produced by the October 2000 meeting of WP8B. It contains a draft new question on the compatibility between short range communications and radar devices using ultra wide band modulations and aeronautical safety-of-life services has been forwarded to WP 1A for consideration since the use of these devices may have consequences on other radio services as well. The outcome of the discussion in WP 1A is awaited

AMCP WGF ACTION: Review in the light of outcome of the discussion in WP1A


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Working Party 8B

LIAISON STATEMENT TO WORKING PARTY 1A

STUDY OF INTERFERENCE FROM SHORT-RANGE RADIO DEVICESUSING ULTRA-WIDEBAND (UWB) TECHNOLOGY OPERATING

IN THE 1-6 GHz BAND

Various administrations and international organizations are studying, for potential regulatory action, devices that use ultrashort, monocycle pulses, which may occupy up to several giga-hertz of bandwidth. The frequencies used by these devices may overlap all or a portion of the 1-6 GHz band. Such overlap could create harmful interference to a wide range of radio services, including safety-of-life services such as the aeronautical radionavigation service. The Radio Regulations do not contain provisions to accommodate these devices. Some proposed UWB devices might operate at low average power and distribute their power over a wide region of spectrum, which normally yields a low spectral power density for one single device. Nonetheless, the full interference characteristics resulting from complex sequences of UWB pulses, singly and in aggregate, are unknown.WP 8D noted that the Short-Range Devices Maintenance Group in the CEPT has developed draft material identifying subjects to be studied on UWB devices, including: technical definition of UWB devices, frequency bands to be used or avoided, possible limitations to the operation of UWB devices to protect particular existing services, and regulatory treatment and legal aspects. WP 8B noted concerns expressed to date on the protection of existing services such as the mobile service, mobile-satellite service, radio astronomy service and space services. In particular, the effects of the operation of UWB devices on safety services such as the aeronautical mobile service, radionavigation service, and radiolocation service requires special attention. WP 8D was informed that CEPT is planning a workshop on UWB technology to be held in 2001.ICAO has considered the necessity for an analysis of the possible interference potential from UWB devices to the aeronautical safety-of-life services operating within the frequency range of 1-6 GHz. These studies need to take into consideration the aggregate effect of interference caused by the potential widespread operation of UWB devices, should they be approved for use within one or more administrations. Working Party 8B is particularly concerned with potential harmful interference from transmission systems using technologies for which there is no information available in ITU-R. However, UWB technology has the ability to affect multiple services, not just those used for safety-of-life.




Document 1A/28-E1 November 2000English only

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WP 8B, in reviewing aspects related to the introduction of UWB devices, noted that is may be necessary to study the conditions for a safe introduction and implementation of UWB devices. These studies might identify the need for one or more ITU-R Recommendations, providing the technical and operating conditions for UWB devices, to be developed. These conditions could in particular address measures to secure the avoidance of harmful interference to the services operating in the frequency bands in which the UWB devices may operate. Special attention to protection of the safety-of-life services should be given in these studies.WP 8B is of the opinion that a broader attention to the introduction of UWB devices might be required than WP 8B, or even Study Group 8, can offer within its terms of reference, since the introduction of UWB devices might affect all radio services operating in the bands between 1-6 GHz. ICAO has proposed a new Study Question concentrating only on the protection of aeronautical safety-of-life services from interference that can be caused by UWB devices, which is attached to this liaison statement for information purposes. WP 8B has not taken any action on this proposal.WP 1A is invited to review this matter with a view to identifying the need for ITU-R to initiate, through a new Study Question, studies on UWB devices. Administrations are further invited to monitor UWB-related developments to determine if and when action within ITU-R is warranted.


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ANNEX

DRAFT NEW QUESTION

COMPATIBILITY BETWEEN SHORT RANGE COMMUNICATIONS AND RADAR DEVICES USING ULTRA-WIDEBAND (UWB) MODULATIONS

AND AERONAUTICAL SAFETY-OF-LIFE SERVICES


consideringa) that UWB devices are planned to operate across numerous frequency bands in the range of 1 to 6 GHz;b) that UWB imaging devices may offer new capabilities to public safety, construction, engineering, science and law enforcement;c) that typical emissions from UWB devices are at a low average power;d) that the potential for interference from UWB to aeronautical safety-of-life services services, has not yet been adequately addressed;e) that the aggregate effects of interference from a large numbers of UWB devices on the existing electromagnetic environment has not been studied;f) that the spectrum requirements for UWB devices vary according to operational usage;g) that UWB devices might be considered for unlicensed operations without protection from other telecommunication services,

decides that the following Question should be studied1 What power levels and other technical criteria (for example, peak-to-average power, pulse repetition frequency, dithering of the signal, pulse width) could be allowed for UWB devices to ensure that harmful interference is not caused to telecommunication services, particularly safety services, such as aeronautical radionavigation?2 What are the spectrum requirements that could be used to support UWB devices that may allow global access and application?3 What operating parameters are proposed and what is the mechanism for interference to other services?4 What measures are required to secure a reliable operation of UWB considering the electromagnetic environment for which they are proposed? What UWB receiver characteristics are necessary to ensure operations in the existing environment?5 What categories of applications can be identified for these devices and what should their allocation be?

further decides1 that the results of the above studies should be included in (a) Recommendation(s);2 that the above studies should be completed by December 2001.

________________


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Part 5Draft revision to question ITU-R 216-1/8 on the "Compatibility of radionavigation, Earth exploration-satellite (active), Space research (active) and radiolocation services operating in the 5350 - 5650 MHz and 2900 - 3100 MHz band." (ITU-R Document SG8/16)


This paper is based on on Document 8B/TEMP/13, produced by the October 2000 meeting of WP8B. The proposed amendments mainly serve the purpose of better defining the scope of the studies.

AMCP WGF ACTION: Review


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Chairman, Working Party 8B

DRAFT REVISION TO QUESTION ITU-R 216-1/8*

COMPATIBILITY OF RADIONAVIGATION, EARTH EXPLORATION-SATELLITE (ACTIVE), SPACE RESEARCH (ACTIVE), AND RADIOLOCATION SERVICES

OPERATING IN THE BAND5 350-5 650 MHz AND COMPATIBILITY BETWEEN THE RADIONAVIGATION AND RADIOLOCATION SERVICES IN THE BAND 2900-3100

MHz

(1997-1998)


consideringa) that the radionavigation service provides a safety of life function (RR S4.10) and harmful interference to it cannot be accepted;b) that radars in the radiolocation service operate on a primary basis worldwide in bands including the 3 100-3 300 MHz band and operate on a secondary basis to the radionavigation service in several bands around 3 and 5 GHz;;c) that considerable radiolocation spectrum (approximately 1 GHz) has been removed or downgraded since WARC-79, particularly affecting the band 3 400-3 700 MHz, and that a need is emerging for increased primary spectrum allocation for the radiolocation service;d) that the International Maritime Organization (IMO) has recently increased their safety requirements for shipborne radars that lead to the need for use of shorter pulse widths;e) that Recommendation ITU-R M.1372 identifies interference reduction techniques which enhance compatibility among pulsed radars;f) that radiolocation services, while recognizing radionavigation as a safety service as delineated in RR S4.10, have demonstrated compatible operations with radionavigation services in the bands 2 900-3 100 MHz and 5 350-5 650 MHz over many years because of using similar system characteristics of low duty cycle emissions, scanning beams, and interference reduction techniques;g) that the active spaceborne earth sensors in the Earth exploration-satellite and space research services have demonstrated compatible operations with the radiolocation service in several bands over many years,h) that Resolution 800 agenda item 1.17 calls for WRC-03 to consider upgrading the status of radiolocation allocations in the 2900-3100 MHz band;

* This Question should be brought to the attention of the International Civil Aviation Organization (ICAO), the IMO and the Comité International radio-maritime (CIRM).




Document 8/16-E26 October 2000English only

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j) that Resolution 800 agenda item 1.5 and Resolution 736 call for WRC-03 to consider allocating the 5460-5570 MHz band to the earth exploration satellite (active) and space research (active) service and to consider allocating the 5470-5570 MHz band to the mobile service for wireless access systems including RLAN, and to review the status of the radiolocation service with a view to upgrading it in the frequency range 5150-5725 MHz.

decides that the following Questions should be studied

1 What are the technical characteristics, protection criteria, and other factors of radiolocation and radionavigation services needed to conduct studies of compatibility between these services in the bands 2 900-3 100 MHz and 5 350-5 650 MHz?

2 What is the feasibility of sharing between the radiolocation and radionavigation services in the 2900-3100 MHz band?3 What is the feasibility of sharing between the aeronautical radionavigation and radiolocation services in the 5350-5470 MHz band?4 What is the feasibility of sharing between the radionavigation and radiolocation services in the 5460-5470 MHz band?5 What is the feasibility of sharing between the maritime radionavigation and radiolocation services in the 5470-5650 MHz band?6 What is the feasibility of sharing between the mobile (RLAN) and radiolocation services in the 5470-5650 MHz band?

further decides

1 that the results of the above studies should be included in one or more Recommendations;

2 that the above studies should be completed by 2003.

NOTE 1 –These studies need to respect the safety-of-life considerations of the radionavigation service expressed in RR S4.10 to ensure that future safety systems can operate without harmful interference.

______________


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Part 6Preliminary draft new recommendation ITU-R M. – Characteristics of and protection criteria for radiolocation aeronautical radionaviafation and meteorological radars operating in the frequency bands between 5 250 and 5 850 MHz (ITU-R Document 7C/42-E)


This paper is based on on Document 8B/TEMP/25, produced by the October 2000 meeting of WP8B. It contains a liaison statement to working party 7C and JTG 4-7-8-9 containing information for conducting sharing studies in frequency bands between 5250 and 5850 MHz. It makes reference to ITU-R Document 8B/37-E (also attached). Information of aeronautical airborne weather radar is relevant.



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Source: Doc. 8B/TEMP/25

Working Party 8B

LIAISON STATEMENT TO WORKING PARTY 7C AND JOINT TASK GROUP 4-7-8-9

INFORMATION FOR CONDUCTING SHARING STUDIES IN FREQUENCY BANDS BETWEEN 5 250 AND 5 850 MHz

At its meeting in Geneva, 18-27 October, 2000, Working Party 8B reviewed several input documents related to sharing in the bands near 5 GHz. One of the documents submitted (Doc. 8B/37) was a Preliminary Draft New Recommendation- “Characteristics of and Protection Criteria for Radiolocation, Aeronautical Radionavigation, and Meteorological Radars Operating in the Frequency Bands Between 5 250 and 5 850 MHz”. This information should assist in completing sharing studies in the bands between 5 250 and 5 850 MHz.Working Party 8B will further review the sharing study contained in Doc. 8B/7 (source: Doc. 7C/TEMP/15) through a correspondence group. However, Working Party 8B noted that results presented on the sharing between EESS and the radiodetermination service (RR S5.448A and S5.448B apply) and observed that the conclusion on the feasibility of sharing is limited to the assumptions on the characteristics of the EESS that were used in the study. It was noted by Working Party 8B that this should be reflected in any regulatory provision that might need to accompany a primary allocation to EESS in the frequency range 5 460-5 570 MHz.

_______________




Document 4-7-8-9/8-EDocument 7C/42-E31 October 2000English only

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Received: 12 October 2000

Subject: Question ITU-R 226/8

United States of America

PRELIMINARY DRAFT NEW RECOMMENDATION ITU-R M.

CHARACTERISTICS OF AND PROTECTION CRITERIA FOR RADIOLOCATION, AERONAUTICAL RADIONAVIGATION, AND

METEOROLOGICAL RADARS OPERATING IN THE FREQUENCY BANDS BETWEEN 5 250 AND 5 850 MHz

The attached preliminary draft new recommendation (pdnr) presents the technical characteristics and protection criteria of meteorological , radiolocation and aeronautical radionavigation radars operating in the bands between 5 250–5 850 MHz This information can be used for conduction sharing studies between incumbent systems operating between 5 250 and 5 850 MHz and new services.

Attachment: 1




Delayed ContributionDocument 8B/37-E13 October 2000English only

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ATTACHEMENT

PRELIMINARY DRAFT NEW RECOMMENDATION ITU-R M.

CHARACTERISTICS OF AND PROTECTION CRITERIA FOR RADIOLOCATION, AERONAUTICAL RADIONAVIGATION, AND

METEOROLOGICAL RADARS OPERATING INTHE FREQUENCY BANDS BETWEEN 5 250 AND 5 850 MHz

Rec. ITU-R M.1464

SummaryThis Recommendation describes the technical and operational characteristics of, and protection criteria for radars operating in the frequency band 5 250–5 850 MHz. These characteristics are intended for use when assessing the compatibility of these systems with other services.The ITU Radiocommunication Assembly,

consideringa) that antenna, signal propagation, target detection, and large necessary bandwidth

characteristics of radar to achieve their functions are optimum in certain frequency bands;

b) that the technical characteristics of radiolocation, radionavigation and meteorological radars are determined by the mission of the system and vary widely even within a band;

c) that the radionavigation service is a safety service as specified by RR No. S4.10 and harmful interference to it cannot be accepted;

d) that considerable radiolocation and radionavigation spectrum allocations (amounting to about 1 GHz) have been removed or downgraded since WARC-79;

e) that some ITU-R technical groups are considering the potential for the introduction of new types of systems (e.g. fixed wireless access and high density fixed and mobile systems) or services in bands between 420 MHz and 34 GHz used by radionavigation, radiolocation, and meteorological radars;

f) that representative technical and operational characteristics of radiolocation, radionavigation and meteorological radars are required to determine the feasibility of introducing new types of systems into frequency bands in which the latter are operated;

g) that procedures and methodologies to analyse compatibility between radars and systems in other services are provided in ITU-R M.1461;

h) that radiolocation, radionavigation, and meteorological radars operate in the bands between 5 250- 5 850 MHz;

j) that ground-based radars used for meteorological purposes are authorized to operate in the band 5600 - 5650 MHz on a basis of equality with stations in the aeronautical radionavigation service (see RR No. S5.452),


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recommends1 that the technical and operational characteristics of the radiolocation,

radionavigation, and meteorological radars described in Annex 1 be considered representative of those operating in the frequency bands between 5 250 and 5 850 MHz (see Note);

2 that Recommendation ITU-R M.1461 be used as a guideline in analysing compatibility between radiolocation, radionavigation and meteorological radars with systems in other services; that the criterion of interfering signal power to radar receiver noise power level (I/N) of –6 dB be used as the required protection level for the radiolocation and meteorological radars, and that the criterion (I/N) of –10 dB be used as the required protection level for safety-of-life (per S4.10) radionavigation radars. These protection criteria represent the net protection level if multiple interferers are present;

Note: Recommendation ITU-R M.1313 should be used with regard to the characteristics of maritime radionavigation radars in the frequency band 5 470-5 650 MHz.


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ANNEX 1

Characteristics of radiolocation, aeronautical radionavigationand meteorological radars

1 IntroductionThe bands between 5 250 and 5 850 MHz are allocated to the aeronautical radionavigation service and radiolocation service on a primary basis as shown in Table 1. Ground-based radars used for meteorological purposes are authorized to operate in 5600-5650 MHz on a basis of equality with stations in the maritime radionavigation service (see RR No. S5.452).

Band (MHz) Allocation5 250 – 5 255 Radiolocation5 255 – 5 350 Radiolocation5 350 – 5 460 Aeronautical Radionavigation 5 460 – 5 470 Radionavigation5 470 – 5 650 Maritime Radionavigation (Note

1)5 650 – 5 725 Radiolocation5 725 – 5 850 Radiolocation

NOTE 1- In accordance with S5.452, between 5 600 and 5 650 MHz, ground based radars for meteorological purposes are authorized to operate on a basis of equality with stations in the maritime radionavigation service.

The radiolocation radars perform a variety of functions, such as tracking space launch vehicles and aeronautical vehicles undergoing developmental and

operational testing, sea and air surveillance, environmental measurements (e.g., study of ocean water cycles and weather phenomena

such as hurricanes), Earth imaging, and national defense and multinational peacekeeping.The aeronautical radionavigation radars are used primarily for airborne weather avoidance and windshear detection, and perform a safety service (see RR No. S4.10). The meteorological radars are used for detection of severe weather elements such as tornadoes, hurricanes and violent thunderstorms. These weather radars also provide quantitative area precipitation measurements so important in hydrologic forecasting of potential flooding. This information is used to provide warnings to the public and it therefore provides a safety-of-life service.Recommendation ITU-R M.1313 should be used with regard to the characteristics of maritime radionavigation radars in the frequency band 5 470–5 650 MHz.


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2 Technical characteristics The bands between 5 250 and 5 850 MHz are used by many different types of radars on land-based fixed, shipborne, airborne, and transportable platforms. Tables 1 and 2 contain technical characteristics of representative systems deployed in these bands. This information is sufficient for general calculation to assess the compatibility between these radars and other systems.


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TABLE 1: CHARACTERISTICS OF AERONAUTICAL RADIONAVIGATION AND METEOROLOGICAL RADAR SYSTEMS


Characteristics Radar A Radar B Radar C Radar D Radar E Radar F

Function Meteorological Meteorological Meteorological Aeronautical Radionavigation

Meteorological Meteorological

Platform type (airborne, shipborne, ground)

Ground/Ship Airborne Ground Airborne Ground Ground

Tuning range (MHz) 5300-5700 5370 5600-5650 5440 5600-5650 5300-5700

Modulation N/A N/A N/A N/A N/A N/A

Tx power into antenna 250 kW Peak

125 kW Avg.

70 kW Peak 250 kW Peak

1500 W Avg.

200 W Peak 250 kW Peak 250 kW Peak

Pulse width (s) 2.0 6.0 0.05 - 18 1 – 20 1.1 0.8-2.0

Pulse rise/fall time (s) TBD TBD TBD TBD TBD TBD

Pulse repetition rate (pps) 50, 250 and

1200

200 0-4000 180 - 1440 2000 250-1180

Output device TBD TBD Klystron TBD TBD TBD

Antenna pattern type (pencil, fan, cosecant-squared, etc.)

Conical TBD Pencil Pencil TBD TBD

Antenna type (reflector, phased array, slotted array, etc.)

Solid metal parabolic TBD Parabolic Slotted array TBD TBD

Antenna polarization TBD Horizontal TBD TBD Horizontal Horizontal

Antenna mainbeam gain (dBi) 46 dBi 37.5 44 34 50 40

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Table 1 (Continued)

Characteristics Radar A Radar B Radar C Radar D Radar E

Antenna elevation beamwidth (degrees)

4.8 4.1 0.95 3.5 <0.55

Antenna azimuthal beamwidth (degrees)

0.65 1.1 0.95 3.5 <.55

Antenna horizontal scan rate (degrees/s)

0.65 TBD 0-36

(0-6 rpm)

20 TBD

Antenna horizontal scan type (continuous, random, 360, sector, etc.)

360 TBD 360 Continuous TBD

Antenna vertical scan rate (degrees/s)

Not applicable TBD N/A 45 TBD

Antenna vertical scan type (continuous, random, 360, sector, etc.) (degrees)

Not applicable TBD N/A Continuous TBD

Antenna sidelobe (SL) levels (1st SLs and remote SLs)

-26 TBD -35 -31 -27

Antenna height (m) TBD N/A 10 Aircraft altitude TBD

Receiver IF 3 dB bandwidth TBD TBD 20 MHz TBD

Receiver noise figure (dB) TBD TBD 4 5 2.3

Minimum discernible signal(dBm)

–110 TBD TBD TBD TBD


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Table 2: Characteristics of Radiolocation Systems

Characteristics Radar H Radar I Radar J Radar K Radar L Radar M Radar N

Function Instrumentation Instrumentation Instrumentation Instrumentation Instrumentation Surface and air search

Surface and air search

Platform type (airborne, shipborne, ground)

Ground Ground Ground Ground Ground Ship

Tuning range (MHz) 5300 5350-5850 5350-5850 5400-5900 5400-5900 5300 5450-5825

Modulation N/A None None Pulse/chirp pulse

Chirp pulse Linear FM None

Tx power into antenna 250 kW 2.8 MW 1.2 MW 1.0 MW 165 kW 360 kW 285 kW

Pulse width (s) 1.0 0.25, 1.0, 5.0 0.25, 0.5, 1.0 0.25-1 (plain)

3.1-50 (chirp)

100 20.0 0.1/0.25/1.0

Pulse rise/fall time (s) TBD TBD TBD TBD TBD TBD 0.03/0.05/0.1

Pulse repetition rate (pps) 3000 160, 640 160, 640 20-1280 320 500 2400/1200/750

Chirp bandwidth (MHz) N/A N/A N/A 4.0 8.33 1.5

RF emission bandwidth -3 dB

-20 dB

TBD TBD TBD TBD TBD TBD 5.0/4.0/1.2

16.5/12.5/7.0

Antenna pattern type (pencil, fan, cosecant-squared, etc.)

Pencil Pencil Pencil TBD TBD TBD

Antenna type (reflector, phased array, slotted array, etc.)

Parabolic

Reflector

Parabolic Parabolic Phased Array Phased Array TBD Traveling wave feed horn array

Antenna polarization TBD Vertical/Left-hand circular

Vertical/Left-hand circular

TBD TBD TBD

Antenna mainbeam gain (dBi) 38.3 54 47 45.9 42 28.0


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Table 2: (Continued)

Characteristics Radar H Radar I Radar J Radar K Radar L Radar M Radar N

Antenna elevation beamwidth (degrees)

2.5 0.4 0.8 1.0 1.0 24.8

Antenna azimuthal beamwidth (degrees)

2.5 0.4 0.8 1.0 1.0 2.6

Antenna horizontal scan rate (degrees/s)

N/A (Tracking)

N/A (Tracking) N/A (Tracking) TBD TBD TBD

Antenna horizontal scan type (continuous, random, 360, sector, etc.)

N/A (Tracking)


Antenna vertical scan rate (degrees/s)

N/A (Tracking)


Antenna vertical scan type (continuous, random, 360, sector, etc.) (degrees)

N/A (Tracking)


Antenna sidelobe (SL) levels (1st SLs and remote SLs)

TBD TBD TBD TBD TBD TBD

Antenna height (m) TBD 20 8-20 TBD TBD TBD

Receiver IF 3 dB bandwidth 1 MHz 4.8, 2.4, 0.25 4, 2, 1 TBD TBD TBD

Receiver noise figure (dB) TBD 5 5 TBD TBD TBD

Minimum discernabile signal (dBm) TBD TBD TBD TBD TBD TBD(short/medium

-102 (wide


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3 Operational characteristics3.1 Meteorological radars

Both airborne and ground-based meteorological radars operate within the frequency range 5 250–5 850 MHz, the technical characteristics of which are given in Table 1. The ground-based weather radar systems are used for flight planning activities and are often collocated at airports worldwide, to provide accurate weather conditions for aircraft. Therefore, these radars are also in operation continuously 24 hours per day. Some meteorological radars operating in this band use Doppler radar technology to observe the presence and calculate the speed and direction of motion of severe weather elements such as tornadoes, hurricanes and violent thunderstorms. Meteorological radars also provide quantitative area precipitation measurements so important in hydrologic forecasting of potential flooding. The severe weather and motion detection capabilities offered by these radars contribute toward an increase in the accuracy and timeliness of warning services.The airborne meteorological radars are used for both hurricane research and reconnaissance. The aircraft penetrate the eyewall repeatedly at altitudes up to 20,000 feet and as low as 1,500 feet. The aircraft collect research-mission data critical for computer models that predict hurricane intensity and landfall. Other aircraft penetrate hurricanes at higher, less turbulent altitudes (30,000-45,000 feet) to determine the position of the hurricane eye.

3.2 Aeronautical radionavigation radarsRadars operating in the aeronautical radionavigation service in the frequency band 5 350–5 460 MHz are primarily airborne systems used for flight safety. Both weather detection and avoidance radars, which operate continuously during flight, as well as windshear detection radars, which operate automatically whenever the aircraft decends below 2,400 feet, are in use. Both radars have similar characteristics and are principally forward-looking radars which scan a volume around the aircrafts flight path. These systems are automatically scanned over a given azimuth and elevation range, and are typically manually (mechanically) adjustable in elevation by the pilot (who may desire various elevation “cuts” for navigational decision-making).

3.3 Radiolocation radarsThere are numerous radar types, accomplishing various missions, operating within the radiolocation service throughout the range 5 250-5 850 MHz. Table 2 gives the technical characteristics for several representative types of radars that use these frequencies that can be used to assess the compatibility between radiolocation radars and systems of other services. The operational use of these radars is briefly discussed in the following text.Test range instrumentation radars are used to provide highly accurate position data on space launch vehicles and aeronautical vehicles undergoing developmental and operational testing. These radars are typified by high transmitter powers and large aperture parabolic reflector antennas with very narrow pencil beams. The radars have autotracking antennas which either skin track or beacon track the object of interest. (Note that radar beacons have not been presented in the Tables; they normally are tuneable over 5 400-5 900 MHz, have transmitter powers in the range 50-200 Watts peak, and serve to rebroadcast the received radar signal.) Periods of operation can last from minutes up to 4-5 hours, depending upon the test program. Operations are conducted at scheduled times 24 hours/day, 7 days/week.Shipboard sea and air surveillance radars are used for ship protection and operate continously while the ship is underway as well as entering and leaving port areas. These surveillance radars usually employ moderately high transmitter powers and antennas which scan electronically in elevation and mechanically a full 360 degrees in azimuth. Operations can be such that multiple ships are operating these radars simultaneously in a given geographical area.


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Other special-purpose radars are also operated in the band 5 250-5 850 MHz. Radar O (Table 2) is an airborne synthetic aperture radar which is used in land-mapping and imaging, environmental and land-use studies, and other related research activities. It is operated continuously at various altitudes and with varying look-down angles for periods of time up to hours in duration which depends upon the specific measurement campaign being performed.

4. Protection criteriaThe desensitizing effect on radars operated in this band from other services of a CW or noise-like type modulation is predictably related to its intensity. In any azimuth sectors in which such interference arrives, its power spectral density can simply be added to the power spectral density of the radar receiver thermal noise, to within a reasonable approximation. If power spectral density of radar-receiver noise in the absence of interference is denoted by N0 and that of noise-like interference by I0, the resultant effective noise power spectral density becomes simply I0 N0. An increase of about 1 dB for the meteorlogical and radiolocation radars would constitute significant degradation. Such an increase corresponds to an (I N)/N ratio of 1.26, or an I/N ratio of about –6 dB. For the radionavigation service, considering the safety-of-life function, an increase of about 0.5 dB would constitute significant degradation. Such an increase corresponds to an (I+N)/N ratio of about –10 dB. These protection criteria represent the aggregate effects of multiple interferers, when present; the tolerable I/N ratio for an individual interferer depends on the number of interferers and their geometry, and needs to be assessed in the course of analysis of a given scenario.The aggregation factor can be very substantial in the case of certain communication systems, in which a great number of stations can be deployed.The effect of pulsed interference is more difficult to quantify and is strongly dependent on receiver/processor design and mode of operation. In particular, the differential processing gains for valid-target return, which is synchronously pulsed, and interference pulses, which are usually asynchronous, often have important effects on the impact of given levels of pulsed interference. Several different forms of performance degradation can be inflicted by such desensitization. Assessing it will be an objective for analyses of interactions between specific radar types. In general, numerous features of radiodetermination radars can be expected to help suppress low-duty cycle pulsed interference, especially from a few isolated sources. Techniques for suppression of low-duty cycle pulsed interference are contained in Recommendation ITU-R M.1372 – Efficient use of the radio spectrum by radar stations in the radionavigation service.

________________________


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Part 7Revised work plan for working party 8B for completing urgent studies under question ITU-R 216/8 (Attachment 5 to ITU-R Document 8B/49-E - Report of the eighth meeting of Working Party 8B)


This paper is based on on Document 8B/TEMP/14, produced by the October 2000 meeting of WP8B.A revised workplan for the completion of studies on the compatibility of radionavigation and radiolocation services operating in the band 2900 - 3100 MHz and 5350 - 5650 MHz has been agreed.

AMCP WGF ACTION: REVIEW


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ATTACHMENT 5 (TO ITU-R DOCUMENT 8B/49-E)

(Source: Documents 8B/TEMP/14 and 8B/108, Attachment 4)

REVISED WORKING PARTY 8B WORK PLAN FOR COMPLETING URGENT STUDIES UNDER QUESTION ITU-R 216/8

1 IntroductionITU-R has approved and revised Question ITU-R 216-1/8, entitled "Compatibility of radionavigation and radiolocation services operating in the bands 2 900-3 100 MHz and 5 350-5 650 MHz". That Question will serve as the framework to conduct compatibility studies in ITU-R. Question ITU-R 216-1/8 states that studies are to be completed by 2001. However, the WRC schedule has since been revised, so that it is now appropriate for studies to be completed by 2003. WRC-2000 adopted Resolution 800 agenda item 1.17 calling for WRC-03 to consider upgrading the status of radiolocation allocations in the 2 900-3 100 MHz band. It also adopted Resolution 736, as well as agenda item 1.5 of Resolution 800, calling for WRC-03 to consider, inter alia upgrading the status of radiolocation allocations in the 5 350-5 650 MHz band. These two Resolutions also call inter alia for consideration of allocating the 5 470-5 725 MHz band to the mobile service (for "wireless access systems including RLANs") and consideration of additional primary allocations for the Earth exploration satellite service (active) and space research (active) in the frequency range 5 460-5 570 MHz.WRC-2000 separated the WRC-03 agenda item for considering upgrades of radiolocation allocation in the 2 900-3 100 MHz band from the agenda item for considering upgrades of radiolocation allocation in the 5 350-5 650 MHz band, and agenda item 1.5 involves consideration of allocating parts of the 5 350-5 650 MHz band to additional services. This proposed work plan is based on similar band-sharing studies that have been performed in ITU-R. It contains an approach for conducting studies on the feasibility of sharing both the 2 900-3 100 MHz and 5350-5650 MHz bands between radiolocation and other services allocated on a co-primary basis in these bands.

2 ObjectiveThe objective of the studies is to develop appropriate Recommendations covering the following topics:• Technical and operational characteristics• Performance requirements• Protection criteria• Studies of compatibility and feasibility of sharing on a co-primary basis.

3 ApproachFor radionavigation and radiolocation systems in these and other bands used by both services, studies will be performed to define technical and operational characteristics, performance requirements, protection criteria and feasibility of sharing. The studies should be performed as described in the following sections.


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3.1 Technical and operational characteristics of radionavigation and radiolocation systems

The studies should address technical and operational characteristics of radionavigation and radiolocation systems needed to perform sharing studies. These systems should include representatives of each major category of the systems in each service; for example, the list of maritime radionavigation systems should include primary navigation radars as well as racons or other transponders.Pertinent technical and operational characteristics for each representative system should include the following, if available:

3.1.1 Technical characteristics• Tuning range and operational tuning flexibility• Transmitter waveform type, including pulse-compression type• Transmitter pulse width• Peak transmitter power• PRFs and transmit duty ratios; PRF jitter or stagger• Transmitter 3 dB bandwidth• Main-beam antenna gain• e.i.r.p. (if transmitter power is not specified)• Antenna pattern type (pencil, fan, cosecant-squared, etc.)• Side-lobe levels (1st SLs and remote SLs)• Antenna pattern envelope or gain probability distribution• Polarization• Antenna scan type (continuous, random, 360, sector,...) and scan rate• RF receiver bandwidth• Receiver RF and IF saturation levels and recovery times• Receiver IF bandwidths• Processing gain relative to random noise• Doppler filtering bandwidth (a measure of coherent integration, and hence of processing

gain, which discriminates against asynchronous pulses)• Pulse compression ratio• Interference-rejection features• RF and/or IF limiting levels• Evolving trends in radar design and capabilities

3.1.2 Operational characteristics• Mission description• Numbers of systems deployed• Geographical distribution• Distribution of operating frequencies within band• Fraction of time in use


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• Fraction of active time spent in horizon scans• Fraction of active time spent in various functional modes (power management, band

occupancy, etc.)• Redundancy and fusion of navigation data from multiple sources, including

radionavigation-satellite sources of 2 900-3 100 MHz radiolocation and maritime radionavigation systems. Technical and operational characteristics are presented in Recommendation ITU-R M.1460 and Recommendation ITU-R M.1313.

3.1.3 Applicable ITU-R documentsMany of the characteristics of radionavigation radars in the 2 900-3 100 MHz and 5 470-5 650 MHz bands can be taken from existing ITU-R Recommendations. In particular:Characteristics of radiolocation and airborne radionavigation systems operating in the5 350-5 650 MHz band are being developed for a new ITU-R Recommendation. Characteristics of the predominant primary-allocated user of the 2 900-3 100 MHz band, maritime radionavigation radars, have been documented in Recommendation ITU-R M.1313-1, Technical characteristics of maritime radionavigation radars. Characteristics of radar beacons that operate in conjunction with maritime navigation radars have been documented in Recommendation ITU-R M.824-2 (10/95), Technical parameters of radar beacons (RACONS).Use of the 2 900-3 100 MHz band by the aeronautical radionavigation service is limited (by footnote S5.426) to ground-based radars. Those are expected to have characteristics similar to those of aeronautical radionavigation radars described in Recommendation ITU-R M.1464. That document presents protection criteria for the aeronautical radionavigation radars; however, it says relatively little about the degradation threshold for interference from pulsed radars. The number of aeronautical radionavigation radars using the 2 900-3 100 MHz band has been the subject of fairly extensive inquiries; such use exists but it is quite limited.Characteristics of radiolocation radars using the 2 900-3 100 MHz band have been documented in Recommendation ITU-R M.1460. That document contains protection criteria, but again, it is not very specific about the pulsed interference that is encountered from other radars.Substantial numbers of the radiolocation radars described in Recommendation ITU-R M.1460 have operated in the 2 900-3 100 MHz band for decades without causing harmful interference to or suffering harmful interference from the radionavigation systems in the band. This by itself is a strong indicator of compatibility between the two services.Use of the 5 350-5 470 MHz band by the aeronautical radionavigation service is limited (by footnote S5.449) to airborne radars and associated airborne beacons.Use of the 5 600-5 650 MHz band by ground-based radars for meteorological purposes are authorized to operate on a basis of equality with stations of the maritime radionavigation service.Procedures for assessing the potential for interference between radars and systems in other services have been documented in Recommendation ITU-R M.1461. That Recommendation provides procedures to be used "as long as no more detailed procedures are available". However, its procedures for assessing interference to radars apply mainly to continuous, noise-like interference rather than to the pulsed interference that radars produce.Techniques used in radars for suppressing low-duty-cycle pulsed interference are described in Recommendation ITU-R M.1372, Efficient use of the radio spectrum by radar stations in the radiodetermination service. Such techniques are highly pertinent to enhancement of compatibility between low-duty-cycle pulsed radar systems.Recommendation ITU-R M.629 (07/86), Use of the radionavigation service of the frequency bands 2 900-3 100 MHz, 5 470-5 650 MHz, 9 200-9 300 MHz, 9 300-9 500 MHz and 9 500-9 800 MHz, can also be considered.


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3.2 Performance requirementsThe performance requirements of radionavigation and radiolocation systems, along with the associated fraction/percent of time that these need to be met, are to be identified. These requirements can take forms such as the following measures of performance, with acceptable threshold values for each of them:• Required detection range with associated radar cross section• Required report update rate• Target-tracking capacity• Dependence on geographical locationPerformance requirements for a radar serving a position-location function might be much less demanding than those for one serving a collision-avoidance function. These thresholds may also be functions of geographical location; for example, requirements might be more demanding or less demanding depending on distance from continental shorelines.

3.3 Protection criteriaThese are provided for radiolocation systems in Recommendation ITU-R M.1460 and for land-based aeronautical radionavigation systems in Recommendation ITU-R M.1464.

3.3.1 Types of interference effectsSystems might fail to meet their performance requirements if undesired signals inflict excessive amounts of various types of interference degradation. Depending on the specific interacting systems and their deployments, those types might include:

3.3.1.1 Diffuse effects• Desensitization or reduction of detection range• Desired-signal dropouts: lowering of valid report update rateBecause of their low duty ratio and antenna beam scanning, the pulsed interference that is inflicted by radars is unlikely to produce very substantial effects of these kinds.

3.3.1.2 Discrete effects• Detected interference: increase of false-alarm or false-response rateThe pulsed interference that is inflicted by radars can produce effects of this kind.

3.3.2 Associated with those types of degradation, the protection criteria could consist of threshold values of parameters such as the following:• Tolerable reduction of detection range, with associated radar cross section (where

applicable)• Associated tolerable desensitization

• Tolerable missed-scan rate• Interference-to-noise ratio, expressed in terms of:

• pulse-peak, • average, or• single-spectral-line

• Tolerable maximum false-alarm or false-response rateFor some types of systems, the protection criteria might best be determined empirically.It could be more useful to specify the threshold interference-to-noise ratio after IF filtering or after asynchronous-pulse rejection circuitry or postdetection processing, rather than at the antenna/receiver


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port. This is so because the numbers, widths and amplitudes of undesired pulses emerging from IF and pulse-processing circuitry can be altered by large and varying degrees by that circuitry, depending on the type of pulse waveform that is received. For example, undesired chirped pulses whose frequency is swept rapidly through the receiver's IF passband could produce pulses at the IF output that are much narrower and weaker than the input pulses, and the energy of undesired pulses that are asynchronous with the desired pulses would be diluted by being spread over many range positions. Hence there is no well-defined threshold interference-to-noise ratio at the antenna port, whereas the threshold value could be meaningfully established, at least as a function of pulse width and pulse-repetition rate, at the IF/processor output port. If the IF circuitry and pulse processing have been adequately described, such specification could facilitate proper accounting for their effects.

3.4 Studies of compatibility and feasibility of band sharingThese can draw upon the technical and operational characteristics, performance requirements and protection criteria. They will use analyses to assess the specified measures of undesired-signal effects that are expected in representative scenarios, worst-case situations or over global averages of deployed and operating systems.The analyses might consist of simple manual calculations, or they might use computer algorithms. They might compute probabilities of interference directly, or they might simulate representative operational scenarios and derive statistical inferences from them. Each analysis would determine whether undesired-signal energy impinged on systems in the other service(s) satisfies the protection criteria.Alternatively, empirical tests might be performed involving a particular combination of systems or range of parameters, and compatibility findings might be derived from the test results.The extensive experience from common use of bands by radiolocation and radionavigation systems, as well as spaceborne active sensors, should also be considered. That experience need not be limited to the 2.9-3.1 GHz band. Much of this has already been done in Recommendation ITU-R M.1460. Such experience is a useful tool for assessing compatibility, particularly since it has been extensive and prolonged. In some ways, experience from common use of bands constitutes the best form of empirical assessment. Many radionavigation and radiolocation systems are aboard mobile platforms, making it difficult to define representative operational scenarios, but real scenarios are automatically accounted for when drawing on actual operational experience. If available, examples of common use of bands by radionavigation and radiolocation systems aboard the same mobile platform could be especially informative.The analyses should seek to identify factors that have contributed to compatible operation in common bands as well as factors that have led to any incompatibilities that might have been observed. They should also develop estimates of compatibility that would prevail with foreseeable new systems introduced into the common bands. They can be used as a basis for ITU-R Recommendations regarding feasibility of, and methods for, sharing of these bands. In these analyses, the following topics merit attention:Mechanisms that aggravate effects of undesired signals:• Clutter cross-modulation• Ducted propagation

• (At frequencies below 3 100 MHz, this is virtually limited to other than evaporation ducts.)

3.4.1 Mechanisms that mitigate effects of undesired signalsThese lie in two categories: mechanisms that are intrinsic to the system designs and operational procedures that can be taken to mitigate interference.Mechanisms that are intrinsic to system design include these:• IF rejection of on-tuned undesired signals

• Reduction of pulse amplitude


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• Reduction of pulse width• IF rejection of off-tuned undesired signals• Asynchronous pulse rejection ("de-fruiters", "PRF discriminators" or "pulse-to-pulse

correlation")• Reduction of pulse numbers

• Processing gain/loss on undesired signals• pulse compression and Doppler processing

• Intermittency of interference due to scanning of undesired-signal source beam• Use of random scan patterns

• Reduction of undesired-signal energy by limiter actionAmong these factors, the asynchronism between the antenna scanning of radiolocation radars and radionavigation radars is particularly important. It is especially effective in avoiding generation of false targets in victim radars, since it causes any false alarms that occur to appear at rapidly and randomly varying directions so they are not interpreted as valid targets.As a result of increasing computational capability and its integration into radar systems, radiolocation radars of modern design can reasonably be expected to be capable of flexibility in their operational procedures that can be exploited to mitigate interference. These options might include:• Avoidance of operation on certain frequencies in selected azimuth/elevation sectors• Power management; i.e. reduction of transmit power in those sectors• Selection of pulse waveforms that lessen the spectral power flux-density radiated in

those sectors

4 Conduct of workTo facilitate the work, exchange of technical characteristics, permissible undesired-signal levels and other needed information may be accomplished by correspondence. Since all the systems involved in this band are radars or radar-related systems, the Radar Correspondence Group is an appropriate vehicle for facilitating this work. This would establish a single point of contact among the interested parties and facilitate work during the interval between working party meetings.

ANNEX A

(to Attachment 5)

Tables of technical characteristics

Tables in formats similar to those of Table 1 are recommended for inclusion in the studies on technical and operational characteristics of radionavigation and radiolocation systems. The characteristics listed in Table 1 are not all-inclusive and, in some cases are not essential. Rather, they are illustrative of what might be needed. Other characteristics should be presented, as appropriate to the particular system involved.


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TABLE 1

Characteristics of radiolocation/radionavigation systems in the band …. - …. MHz

Systems A B C D E F GCharacteristicsTuning range, operational tuning flexibilityTx waveform typePeak Tx PowerTx e.i.r.p. (dBW)Tx pulse widthTx 3 dB bandwidthPRFs; Tx duty ratios; PRF jitterPolarizationAntenna gainAntenna pattern type (pencil, fan, csc-squared)1st SL levelRemote SL levelsAntenna scan type (continuous, random, 360, sector, etc.)Rx RF bandwidthRx RF & IF saturation levels & recovery timesRx IF bandwidthProcessing gain relative to noisePulse-compression ratioInterference-suppression featuresRx RF, IF limit levels


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ANNEX C

(to Attachment 5)

Operational use and future spectrum requirements for maritime radionavigationradars around 3 GHz

1 Worldwide “S-Band” radar populationAt the present time it is estimated that there are more than 30 000 “S-Band” radars at sea, as shown in Table A. All of these “S-Band” radars are in ships with “X-Band” radars. The S-Band population is thought to be growing in both merchant ships and fishing boats.There are also a number, estimated to be about 100, fixed S-Band maritime radars used for the VTS service, pilotage stations and artillery and missile range surveillance. These are mostly situated in Europe.

2 S-Band radar manufactureThe estimated worldwide manufacture of maritime S-Band radar is in Table A. It is estimated that there are at least 11 manufacturers in 8 countries.

3 S-Band radar beacons (racons)Table A includes an estimate of the worldwide racon population. This is about 3 000 systems. They are used to mark navigational hazards and shipping routes. At least 60% of these racons are capable of responding to S-Band radars as well as X-Band radars. The racons and radars have to comply with Recommendation ITU-R M.824-2 which defines the technical characteristics of S and X band racons. There are two known manufacturers of such systems.Additionally, Table A includes the estimated population of radar target enhancers and search and rescue transponders, all of which currently operate in X-Band, but S-Band systems are expected to be developed.

4 Review of maritime radar frequenciesThe use of the various radiodetermination bands for maritime radars is reviewed in Table B. This shows that the 12 GHz to 40 GHz bands have been tried in the past but are not useable due to the absorption and attenuation problems which limit range performance severely. The 5 GHz (C-Band) is not popular for maritime radar as users require two distinct and well separated bands, e.g. the S and X bands, to give really significantly different performance. The main use of C-band has been for navigational purposes in fishing craft in Japan. In the 1 GHz band, 1 215 MHz to 1 300 MHz (L-band) the primary allocation is for the radiolocation service. The radionavigation service is not allocated worldwide, but to several countries as an additional allocation only. Furthermore, it would not be possible to have practical antennae, as these would be nearly 3 times larger than those at S-band. Surface propagation at around 1 GHz over water would have poor performance.


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5 Use of maritime radar frequenciesIn Table C, the operational use of maritime radar is reviewed. This shows that the use of the S-band and X-band are complementary and are for both long and short range. As an example, most Baltic ferries use S-band radar for use in short range applications, to detect the small navigational spar buoys, and also for close range detection in ice with icebreakers in convoys, in order to detect the ships in ice clutter.

6 New IMO requirements for high speed craft and maritime radarRecently IMO has introduced new mandatory requirements for high speed craft and maritime radar as follows:1) a new high speed craft radar performance standard in Resolution A.820 was adopted in November 1995 and came into force for fitting on 1 January 1996. The specification requires a minimum range of 35 metres from an antenna height of only 7.5 metres. This has new frequency implications. The specification also permits the use of smaller S-band antennas than the current maritime standard, recognizing the merit of S-band radar for short range working, particularly in sea clutter. This application would be in the larger high speed craft which are required to carry two radars, at least one of which must be X-band.2) the IMO maritime radar performance standard in Resolution A.477 has been reviewed and a revised standard agreed as Resolution MSC.64(67) Annex 4. This will come into force for all new fittings after 1 January 1999. The range discrimination of all maritime radars, both S-band and X-band, to which the new standard applies, has been improved significantly from 50 metres to 40 metres, which will require shorter pulse lengths.3) a draft International Code of Safety for ships in Polar waters (POLAR Code) has been developed. Article 12.5.1 of this draft Code states:“All ships of Polar Classes 1 through 5 should have one radar fitted with an S-Band (10 cm) scanner for ice navigation.”

7 Frequency requirements for future S-band maritime radars

7.1 Need for retention of the maritime S-band (2 900 MHz-3 100 MHz)S-band radar has been in wide use for maritime navigation for 57 years and its application and use is well proven. The transfer of this application to any other radiodetermination band cannot be contemplated without serious loss to essential marine safety services.

7.2 Use of the 2 900 MHz to 3 100 MHz band for maritime radionavigationSince 1959 S-band maritime radars have been concentrated on the frequency 3 050 ± 30 MHz.The reasons for not being in the centre of the band are largely historical and are partly to do with the use of sub-bands at the bottom end of the band.The primary reasons are:1) From the early 1970s IALA requested that the sub-band 2 900 to 2 920 MHz be reserved for the use of racons, and maritime radars were not permitted to use this sub-band. Although these fixed frequency racon techniques have not, at present, been exploited, the sub-band remains reserved for this purpose until 2001.2) In the late 1970s the USSR wished to introduce a shipborne interrogator transponde system (SIT) in the sub-band 2 930 MHz to 2 950 MHz. This is still permitted under Radio Regulation footnotes S5.425 and S5.427.


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7.3 Sharing the S-band radionavigation bandBecause of the concentration of maritime radars in this band, and also the advent of sharing with other services from 1959, very severe radar interference was experienced on maritime radars by the late 1960s. Fortunately, by the mid 1970s processing techniques e.g. pulse-to-pulse correlation, were starting to become available to reduce such interference. Terms for sharing of 2 900-3 100 MHz by radiolocation on a co-primary basis will need to be carefully examined in order to ensure that such sharing does not cause harmful interference to the maritime radar safety service.

7.4 Re-organization of the bands 2.9 GHz to 3.1 GHz and 3.1 GHz to 3.3 GHzSince 1959 the S-band maritime radars have been concentrated on 3 050 MHz, using short pulse widths of a nominal 80 nanoseconds or less. Large numbers of S-band radars use short pulse lengths of a nominal 50 nanoseconds and have been in use voluntarily for many years. These have been approved by many Administrations in Europe and the USA. There have been no reported problems from unwanted emissions from these radars in the adjacent band of 3.1 GHz to 3.3 GHz.Shorter range working is now required mandatorily by IMO as previously indicated. This requires the use of very short pulse widths with associated frequency requirements. To take account of the resulting wider bandwidths of the transmitted pulses, it will be necessary to seek an extension of the allocated frequency band for maritime radars into the band 3 100 MHz to 3 300 MHz.It should be noted that 10 countries* are already additionally allocated for the radionavigation service on a co-primary basis with radiolocation, in the above band, in the Radio Regulations by footnote.

8 AcknowledgementCIRM have provided the statistics contained in Tables A and B.

* Azerbaijan, Bulgaria, Cuba, Kazakstan, Mongolia, Poland, Kyrgzstan, Romania, Turkmenistan and Ukraine. (Radio Regulation footnote S5.428.)


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TABLE A

Worldwide maritime radar manufacture - (CIRM model)CIRM members manufacturers

Country of production

IMO maritime radar X and S bands

Fishing radar

Yacht radar

Naval radar

River radar

1 JAPAN YES X YES YES2 ITALY YES X and S3 JAPAN YES X and S YES YES YES4 JAPAN YES X and S YES YES YES5 U.K. YES X and S YES YES YES6 U.K./U.S.A. YES X and S YES YES YES7 U.S.A./U.K. YES X and S YES YES YES8 GERMANY YES X and S YES YES9 JAPAN YES X and S YES

Types of radars about 50 about 50 about 50 4 5Non-CIRM

manufacturers10 CHINA YES X and S11 ITALY YES YES12 U.S.A. YES13 JAPAN YES14 JAPAN YES X YES YES15 U.K. YES16 NORWAY YES X and S17 RUSSIA FED. YES X and S18 S.KOREA YES YES

TOTAL ESTIMATED ANNUAL PRODUCTION about 80 000 systems - S band about 2 500TOTAL EXISTING POPULATION circa 800 000 systems - S band > 30 000RACON POPULATION circa 3 000 - > 60% S and X bandRADAR TARGET ENHANCER POPULATION circa 1 000 - all X band. SART POPULATION circa 60 000 all X band.


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TABLE B

Use of maritime radar frequenciesFrequency band Frequency (MHz) ITU primary allocation

(MHz)ITU secondary allocation

(MHz)Comments

2 000-4 000 2 900-3 100 RN3 100-3 300 RL RN

see Note 13 300 to 3 400

see Note 1

2 900-3 100 RL Used by > 30 000 civil maritime radars for radionavigation. Used by about 100 land-based radars for VTS and surveillance of the sea.Used by about 2 000 civil maritime racons

4 000-8 000 5 470-5 650 MRN 5 350-5 650 RL Used by a small number of civil maritime radars for radionavigation, constrained to one particular geographical area

8 000-12 000 8 850-9 000 MRN RL9 200-9 225 MRN RL9 225-9 300 MRN RL

Shore-based radarShore-based radar

9 300-9 500 RN

9 500-9 800 RN RL

9 300-9 500 RL 9 300-9 500 used by about 800 000 maritime radars. Used by about 3 000 maritime racons, some radar target enhancers and about 60 000 search and rescue transponders

12 000-18 000 14 250-14 300 RN Used for very short range maritime radars for berthing of large ships

18 000-27 000 24 250-24 650 RN in Regions 2 and 3

Not used since 1945. See Note 2

Ka and Q 27 000-40 000 31 800-33 400 RN 8 mm (Q) river radar use in the 1960s. Now discontinued due to rain effects and high cost

NOTE 1 – Certain countries use 3 100 to 3 400 MHz for radionavigation.NOTE 2 – The original K band radars at about 24 000 MHz were so close to the water absorption frequency of water vapour and the oxygen absorption band, that ranges proved negligible.RN - Radionavigation MRN - Maritime radionavigation RL - Radiolocation


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TABLE C

Operational use of 3 GHz band and 9 GHz band maritime radars

Characteristic Comparison

Precipitation and sea clutter S-band has superior performance.Azimuth resolution For a given antenna size - X band superior.Coverage at low angles of elevation X band has generally superior performance.Size and cost X band is smaller and less costly.OPERATIONAL USEShort range (0 - 6 nautical miles) navigationAnti-collision S band radars are generally superior to X band in detection and tracking of small targets, such as

fishing boats or spar buoys in sea clutter. When there is no sea clutter, which is a rare event, X band can be superior. S band radars have less precipitation clutter than X band, and thus targets are easier to detect and track in tropical rain. S band is superior in ice clutter for the detection and tracking of icebreakers.

Navigation X band radar has a much more defined picture than S band making recognition of land easier. The superior sea surface cover usually ensures a more distinct picture of low coastlines. For these reasons X band is used for river navigation. X band is superior for superimposition of the radar picture onto electronic charts. X band is superior giving a more distinct picture of the path cut by icebreakers in ice.

Long range (0 - 64 nautical miles) navigationAnti-collision Outside a range of about 6 nautical miles X band generally gives superior range for first detection of

targets. In rain clutter S band will be superior.Navigation X band may give superior detection of low coastlines. S band may give superior detection of high

land.S band gives superior detection of birds hunting tuna and benito up to about 15 miles range.


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Part 8Liaison statements to working party 8F on interference from IMT-2000 and other services (including the radiodetermination service) (ITU-R Document 8F/169-E)


This paper is based on on Document 8B/TEMP/17, produced by the October 2000 meeting of WP8B.Comments on the proposals for a technical basis to introduce in the bands 2700 - 2900 MHz an allocation to the mobile service for elements of IMT-2000 were developed by 8B. This important issue requires careful consideration by WG F and support at the ITU meetings.



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Source: Document 8B/TEMP/17Received : 23 October 2000

Working Party 8B

LIAISON STATEMENT TO WORKING PARTY 8F

RESPONSE TO LIAISON STATEMENTS ON THE DOCUMENTS:

"PROPOSED METHODOLOGY FOR INTERFERENCE ANALYSISBETWEEN IMT-2000 AND THE RADIODETERMINATION

SERVICE" (DOCUMENT 8B/9)

AND

"METHODOLGY FOR ASSESSING THE POTENTIAL FOR INTERFERENCEBETWEEN IMT-2000 AND OTHER SERVICES" (DOCUMENT 8B/10)

At its meeting in Geneva, 18-27 October 2000, WP 8B reviewed the documents with the above titles. WP 8B submits the following comments to WP 8F regarding the applicability and suitability of these methodologies to performing sharing analyses between IMT-2000 and the radiodetermination service.WP 8B notes that Document 8B/9 appears to be a proposed methodology for conducting sharing studies specifically between IMT-2000 and the radiodetermination service while Document 8B/10 appears to apply to sharing studies between IMT-2000 and other radio services in general. In addition WP 8B would like to draw the attention of WP 8F to an existing recommendation, ITU-R M.1461 – "Procedures for Determining the Potential for Interference Between Radars Operating in the Radiodetermination Service and Systems Operating in Other Services", that provides an ITU-R approved methodology for conducting sharing studies between the radiodetermination service and all other radio services. WP 8B believes that ITU-R M.1461 should form the basis of any sharing studies performed between IMT-2000 and the radiodetermination service.Addressing Document 8B/9 (8F/TEMP/23(Rev.1)), WP 8B notes that this document does refer the reader to Recommendation ITU-R M.1461. In addition, the document does provide a good tutorial on the special characteristics of radar systems and discusses the particular sensitivity of radar receivers to undesired signals coupled into the radar main beam. Therefore, any analysis must be based on main beam coupling rather than a probabilistic approach that considers the overall antenna pattern statistics. WP 8B suggests some refinements that should be made to the document. These refinements are indicated in the document in Annex 1.Regarding Document 8B/10 (8F/TEMP/22(Rev.1)), WP 8B does not believe that this methodology is applicable to conducting sharing studies between IMT-2000 and the radiodetermination services.




Document 8F/169-E23 October 2000English only

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In conclusion, WP 8B agrees that the information contained in Document 8B/9, with the attached comments incorporated, can be applied to conducting sharing studies between IMT-2000 and the radiodetermination service provided the methodology outlined in Recommendation ITU-R M.1461 is used as a basis. The methodology outlined in Document 8B/10 is not applicable to the radiodetermination service. As a final note, WP 8B believes since many radar systems fall under the definition of a safety-of-life service, sharing studies must include compatibility tests validating the analysis results.

Attachment:


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ATTACHMENT

Proposed methodology for interference analysis between IMT-2000 and the radio determination service

(Source: Document 8B/9)

1 IntroductionConsideration of the frequency band 2 700-2 900 MHz for use by IMT-2000 systems is currently on the WRC-06 agenda. The band 2 700-2 900 MHz is currently allocated to the aeronautical radionavigation service on a primary basis and the radiolocation service on a secondary basis. Additionally, meteorological radars are afforded equal status to the aeronautical radionavigation service for operation in this band. The aeronautical radionavigation service includes radars providing airport surveillance and air traffic control. These radars perform a safety service as specified by No. S4.10 of the Radio Regulations (RR) and harmful interference to them cannot be accepted. The meteorological radars are used for detection of severe weather such as tornadoes, hurricanes, and violent thunderstorms. Weather radars also provide quantitative area precipitation measurements that are important in hydrologic forecasting of potential flooding. This information is used to provide warnings to the public and therefore provide a safety-of-life service. Since these radars provide essential functions it is vital that this service receive the necessary protection.Therefore, to support the identification of the 2 700-2 900 MHz band for IMT-2000 terrestrial system, allocation appropriate ITU-R sharing and impact assessment studies must be conducted as directed by Resolution [GT PLEN-2/6]. This document introduces a methodology for determining the potential for interference between aeronautical radionavigation and radiolocation services and IMT-2000 terrestrial systems.

2 Radar system operationThe operation of radar systems is based on the transmission of high power narrow/short pulse width emissions and the detection of weak radar target return signals. In some radars the transmitted pulse is shaped to improve the performance. The bandwidth of the received pulses, and the Doppler shifts that occur in the pulse train from being scattered by the target, provide information that is essential for meeting the radar's performance criteria. Since the bandwidth of a signal is inversely proportional to the effective pulse width, a narrow transmitted pulse requires a wide receiver bandwidth for accurate reconstruction and processing of the received signal. Further, effective processing of the received radar pulse requires a high degree of phase linearity across the main lobe of the received pulse spectrum. This stringent requirement for phase linearity typically results in a radar receiver filter roll-off that is more gradual than that attainable for telecommunications systems. This also may lead those unfamiliar with radar system design to conclude that radar receiver bandwidths are unnecessarily large in some systems. For these reasons radars require transmitter and receiver bandwidths which are large compared to those of communications systems to effectively perform their functions. Therefore, narrowing the bandwidth degrades the pulse shapes and effectively reduces radar performance.


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2.1 Radar processingA common misconception concerning radar operation is that the radar operation cycle is equal to a full rotation/scan of the radar antenna. This misconception can lead to the assumption that interference effects should be analysed and considered over the time period of a full rotation/scan (or even many rotations or scans). In reality, radar target returns are processed individually in at least two dimensions, range and azimuth. As described below, radar receiver processing in these two dimensions form resolution "cells" which are evaluated for the presence of radar pulses returned from targets. Interfering signals-even if present for only short periods of time-can corrupt these resolution cells and cause false or lost targets.

2.1.1 Range dimensionFor purposes of illustration, an example radar in the aeronautical radionavigation service may have the following characteristics; a pulse width of 0.6 sec, a pulse repetition frequency (PRF) of 973 pulses per second (pps) and a time period (T=1/PRF) of 1027 sec. Recommendation ITU-R M.1464 contains the characteristics of radars operated in this band around the world. In normal operation, the transmitter of the example radar is connected to the antenna and transmits a very short and high power RF pulse with a 0.6 sec pulse width. The antenna is then connected to the receiver for a period of time equal to 1/PRF minus the pulse width, during which it receives the reflections (echoes) from the targets illuminated by the main beam of the antenna (3 dB Beam-width). In theory radar also receives echoes from targets outside the antenna 3 dB beam-width from the side-lobes and backlobes, but these signals are below the noise level due to low antenna gain (50-60 dB below the main beam since the loss occurs in both the transmit and receive direction) and the 1/R4 law. For this reason in primary radar there is no sidelobe suppression mechanism. The antenna is connected to the transmitter and another 0.6 sec pulse is transmitted. Between each pair of consecutive transmit pulses, the receiver distinguishes approximately 1 000 range cells, each of which is tested for potential target returns

2.1.1.1 Individual-return-pulse detectionThe radar signal processor is an automatic detection device that determines whether an echo is coming from a target or is from noise/interference. This done by setting a threshold called the Constant False Alarm (CFAR) Threshold with the aim of keeping the false alarm/target detection rate steady. The level of this threshold must be set sufficiently high above the noise floor to minimize false detections, but low enough so that the system is not overly desensitized against weak return signals.


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In the case where the level of interference is high the threshold must be increased so as to keep the number of false detections/alarms steady. However, this increased threshold results in the elimination of weak targets and degradation of the detection performance of the radar.

2.1.2 Azimuth dimensionThe transmission/reception cycle is repeated every 1/PRF seconds at the same time the antenna is turning at a steady speed, e.g. 75 deg/sec. The antenna beamwidth is 1.4 deg, so a target is inside the beamwidth for 18.6 msec and will be hit by 18.6 pulses/hits. The echoes that are strong enough to pass the CFAR threshold are declared as detections and used for the estimation of the range and azimuth of the target. Therefore, an undesired signal received during the main beam dwell time may cause loss of targets or an indication of false targets.

3 Interference analysis methodology3.1 Radar model

First and foremost it must be understood that radars are not communication systems and cannot be treated as such in an interference assessment methodology. Knowledge of the basic principles and the operation of radar systems is vital to the development of a viable interference analysis methodology. The averaged or cumulative distributions of interference-to-noise ratio (I/N) or of carrier-to-interference ratio (C/I) are not adequate bases for deciding whether interference exists and compatibility prevails between radars and other systems. The statistics of interactions between systems are not sufficient. Since statistics are representations in which the temporal and spatial dimensions of interactions are integrated out, the effects that might be concentrated at particular times and directions become diluted with occurrences that are spread over all times and all directions, regardless of how irrelevant they might be. For ATC radar, interference arriving on a particular bearing might cause the detection of an approaching aircraft to be delayed or missed for one or more successive scans. This type of delay effectively reduces the detection volume of the radar, and equivalently reduces the amount of critical airspace under the management of air traffic controllers-potentially causing an unsafe condition for one or more aircraft. An accurate analysis model for evaluating compatibility between radars and other services must consider the special characteristics of radar systems and the particular sensitivity of radar receivers to undesired signals coupled into the radar main beam. It is important that any analysis should be based on mainbeam coupling rather than a probabilistic approach that considers the overall antenna pattern statistics. The sweep and rotation (scan) rates of the radar must be adequately represented in the model.

3.2 IMT-2000 network simulationAs a cellular-type network in the mobile service, IMT-2000, will be deployed with mass application and high densities of transmitters. The basis for this simulation methodology is the calculation of the expected communication demand within the cellular network. The results of this methodology indicated that IMT-2000 cellular mobile networks will be organized in a hierarchical structure of four different cell implementations. These cell implementations are the rural, macro, micro and pico.


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The deployment structure of the IMT-2000 system is a key issue for the assessment of compatibility with radars. Critical parameters, such the number of mobile and base stations operating inside the radar coverage region, as well as the total percentage of those stations that are active at any particular time, must be accurately identified and incorporated in the simulation. It may be necessary to expand this simulation to include the total number of stations per kilometre operating in the radar coverage region. It is uncertain whether the methodology for simulating the mature deployment of cellular networks in the mobile service addresses this parameter or if the percent of stations that are active per unit of time can be quantified, so further study must be performed to resolve these issues. As discussed earlier, the statistics of the potential for interference into a radar system are not considered to be conclusive (or possibly relevant) with regard to sharing with systems of other services, as the effects of interference on radar performance can manifest themselves over very short periods of time. However, a statistical model is considered appropriate for characterizing the IMT-2000 RF environment, seen as unwanted signals to radar. Such a model should include typical IMT-2000 base and mobile station deployments, call initiation rates, call "hang times", etc. The incorporation of such a statistical model in a simulation of the potential interference environment from IMT-2000 stations into a radar is considered appropriate as long as the simulation results include the duration and severity of individual interference events.

3.3 Propagation modelIn order to assess the compatibility between IMT-2000 and radars, it is important to be able to predict with reasonable accuracy the interference potential between them using prediction procedures and models. Many interference mechanisms may exist between IMT-2000 and radars and prediction methods are required to address each situation. Therefore, the interference methodology must include a complementary set of propagation models that will address all significant interference propagation mechanisms that can arise. A methodology that includes such interference propagation mechanisms as line-of-sight, diffraction, tropospheric scatter, surface ducting, elevated layer reflection and refraction, and hydrometeor scatter is essential in predicting compatibility between these systems. For analysing interference from IMT-2000 to radars, the methodology must be capable of modeling propagation conditions over area-to-point propagation path. The methodology for analysing interference from radars to IMT-2000, an area propagation model must be used. Neither methodology should take into account site-specific data such as terrain.

3.4 Analysis of resultsThe interference assessment methodology developed uses the power spectral density of an interfering signal at the victim receiver as a key element of the interference calculation process. Algorithms must be developed to calculate the power density spectrum at the victim receiver. Therefore, in order to demonstrate the probability of interference, the results of the simulation will be focused on the Interference-to Noise ratio (I/N) at the receivers of the systems. This instantaneous I/N will be plotted versus %Time. The determination of compatibility between IMT-2000 and radars will be made by analysis of the instantaneous responses of this simulation, not average results. If the I/N exceeds the maximum allowable level for greater than the percentage time that it is allowed, there is incompatibility between the systems. For safety-services, the allowable percentage time for exceeding the level should be 0%.


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4 Interference scenarios4.1 Interference from IMT-2000 into radars

Recommendation ITU-R M.1461 gives the method to determine the compatibility of other systems with radars. The total unwanted signal power being coupled into the radar receiver needs to be compared to the radar receiver noise power level. This interference-to-noise power, or I/N, needs to be computed and compared to the appropriate I/N criterion. The computation method of Recommendation ITU-R M.1461, however, considers only interactions between individual systems rather than those between an individual radar and many potentially interfering sources. In the case of compatibility between a radar and an IMT-2000 environment, simulations of interference from all base and mobile stations into the radar receiver, to include all combinations of mutual antenna mainbeam and sidelobe gain combinations, must be run to determine compatibility. For protection of the radar system, a maximum I/N ratio of –10 dB shall be maintained. Recommendations ITU-R M.1461 and ITU-R M.1464 specify an I/N of –6 dB if the interference source is in one direction only. However, for sources from most azimuths, as with the distribution of IMT-2000 terminals around the radar, a lower I/N= –10 dB is maintained. Compatibility between radars and IMT-2000 systems may exist if the I/N level stays below –10 dB at any instant of time. Some radars can allow a certain amount of interference energy in some of the cells and still adequately perform. The amount of time would be very small and dependent upon the particular design and function of the radar being considered. Though an overall cumulative distribution of interference levels into the radar is not considered useful, whether or not the specific allowed time criterion is exceeded, and how often, should be considered if such criterion is available for the specific radars. (It should be noted that it is typically very difficult to obtain such information on individual radar systems, and nearly impossible for all radar systems operating in a particular frequency band, or likely to be operated in the future. For this reason, radar band sharing studies use the recommended I/N criterion as a hard limit.)

4.2 Interference from radars into IMT-2000The power spectral density of the interfering signal into the IMT-2000 receiver must be determined by use of the methodology described above. Separate simulations for interference into base stations and into mobile stations from the radar transmitter will be run to generate the instantaneous I/N vs %Time plots that will determine compatibility. Interference criteria for the various IMT-2000 radio interfaces have not yet been developed. Some in industry use the stated sensitivity as the interference threshold level while others consider any measurable unwanted signal regardless of level as interference. IMT-2000 Interference criteria must be developed before an accurate analysis of interference from radars into IMT-2000 can be accomplished. There are two possible mechanisms for evaluating interference from radars into IMT-2000 receivers; receiver front-end overload and radar emission coupling within the intermediate frequency of the IMT-2000 terminal. Though not specifically stated in Recommendation M.[IMT.RSPC], the threshold at which receiver front-end overload occurs is estimated to be approximately –25 dBm, based upon the stated sensitivity of 105 dBm and a dynamic range of 80 dB. However, interference to the IMT-2000 system will begin to occur at an interference value at the receiver input that is much less than the 25 dBm, and probably within 12 to 25 dB of the IMT-2000 receiver noise floor. It is this interference mechanism that should be analysed once the actual interference criteria are known.


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The receiver overload analysis is most applicable where IMT-2000 proponents believe that their systems can operate with the radar pulses. Overload must be studied to determine the amount of data that is lost when the radar pulse is not present but the receiver circuitry is recovering from an overload condition. Therefore, compatibility between radars and IMT-2000 systems will not exist if the I/N level surpasses the interference criteria for greater than the allowable percentage of time. Recommendation ITU-R M.1461 provides the methodology for calculating the radar transmitter emission coupling into the IMT-2000 terminal and the calculation of IMT-2000 emission coupling into a radar receiver. The Frequency Dependent Rejection (FDR) values required for this analysis can be calculated in accordance with ITU-R Recommendation SM.337-4.

5 ConclusionsIn response to WRC-2000 Resolution [GT PLEN-2/6] agenda item 3.1 to consider the results of ITU-R sharing and impact assessment studies on the feasibility of sharing in the band 2 700-2 900 MHz this document introduced a methodology for determining the potential for interference between radars and IMT-2000 terrestrial systems. Since radars are instantaneous time and peak power dependent systems the determination of compatibility between IMT-2000 and radars must be made by analysis of the instantaneous responses of the simulation methodology, not probabilistic results.

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Part 9Response to liaison statement from working party 7C on the "sharing between the Earth exploration-satellite service (passive) and the ARNS in the band 4200 - 4400 MHz (ITU-R Document 7C/53E).


This paper is based on on Document 8B/TEMP/20, produced by the October 2000 meeting of WP8B. Amendments to a preliminary draft new recommendation on the "frequency sharing between the Earth exploration-satellite service (passive) and airborne radio altimeters in the aeronautical radionavigation service in the band 4200 - 4400 MHz are proposed with a view to better define and protect the current and future availability of this band for ARNS.

AMCP WGF Action: Review


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Working Party 8B

LIAISON STATEMENT TO WORKING PARTY 7C

SHARING BETWEEN THE EARTH EXPLORATION-SATELLITE (PASSIVE) SERVICE AND THE ARNS IN THE BAND 4 200-4 400 MHz

Working Party 8B thanks Working Party 7C for its liaison statement of 24 March 1999 (Doc. 7C/TEMP/101(Rev.1)) on the above topic. Working Party 8B has not met since the liaison statement was sent and understands that further work has been carried out by Working Party 7C at its intervening meetings, with the latest version of the PDNR being contained in Doc. 7C/TEMP/2(Rev.1) (Attachment 4 to Doc. 7C/32). It is noted that the sharing study annexed to the original PDNR as sent to Working Party 8B in the March 1999 liaison is no longer included in Doc. 7C/TEMP/2(Rev.1). Working Party 8B is of the opinion that it would be of benefit to maintain the sharing study as an annex to the PDNR in order to understand the rationale behind the Recommendation.Working Party 8B would request that it is made clear in the PDNR that there is a possibility – albeit low – of interference into the passive service from the radio altimeters, but that this will not cause difficulties to the EESS use of the band. Further, due to the safety of life use of the band by ARNS, no constraints should be placed upon the current or future use of the band. Working Party 8B also noted that the value quoted in Doc. 7C/TEMP/2(Rev.1) for the antenna backlobe level of the radio altimeter of -30 dBi assumes that no platform is present. The same figure (-30 dBi) was used in Doc. 7C/TEMP/101(Rev.1) (Document 8B/103) where it appeared to assume that the platform was present.The rationale for these requests from Working Party 8B is that the sharing study contained in the original liaison statement from Working Party 7C (Doc. 7C/TEMP/101(Rev.1)) shows that there is a possibility of interference to a radiometer depending on the number of radio altimeters visible to it in a certain area. A statement was also made of the permissibility of loss of data from up to 5% of the radiometer measurement cells, although the study results suggested that any loss of data would be below this level given the numbers of radio altimeters assumed in the study. Working Party 8B also notes that the study assumed that a single radio altimeter would be transmitting on board an aircraft at a given time and that therefore the interfering power from any one aircraft is equal to that from a single radio altimeter, however this was not stated. There may be up to three altimeter systems present on board an aircraft, which may or may not be transmitting simultaneously. Noting that the maximum number of altimeters to avoid interference in the scenario with the lowest protection margin in the March 1999 study (that of altimeter side lobe into radiometer main lobe) is three, the possibility of data loss in a given cell may be increased from the low value anticipated in the study.Working Party 8B has proposed some additional text for the PDNR contained in Doc. 7C/TEMP/2(Rev.1) and these are in the attached annex.Annex: 1




Document 7C/53-E30 November 2000English only

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ANNEX

Source: Document 7C/TEMP/2(Rev.1) (with proposed modifications from Working Party 8B)

PRELIMINARY DRAFT NEW RECOMMENDATION

FREQUENCY SHARING BETWEEN THE EARTH EXPLORATION-SATELLITE (PASSIVE) AND AIRBORNE ALTIMETERS IN THE AERONAUTICAL

RADIONAVIGATION SERVICE IN THE BAND 4 200-4 400 MHz(Question ITU-R 229/7)


consideringa) that the band 4 200-4 400 MHz is allocated on a secondary basis to the Earth exploration-satellite service (passive) by RR S5.438;b) that this band is allocated on a primary basis to the aeronautical radionavigation service for airborne altimeters and that this use will continue and will expand in the future as the number of aircraft in use increases;c) that global warming, being widely recognized as a serious Earth environmental problem, requires continuous global monitoring and surveying of sea surface temperatures (SST) under all weather conditions;d) that seasonal weather forecasting and numerical weather forecasting of potential dangerous weather phenomena such as typhoons and other severe storms, require continuous SST measurements, under all weather conditions;e) that the 4-7 GHz band provides the only capability to globally monitor SST under all weather conditions by passive microwave radiometers on board Earth exploration satellites;f) that the 6-7 GHz band is being overly contaminated by emissions from the fixed service and the fixed-satellite service and that the 4-5 GHz band remains a promising band to monitor SST under all weather conditions;g) that the interference criteria for passive sensors in the Earth exploration-satellite service is included in Recommendation ITU-R SA.1029;h) that studies have shown that there is a low probability of interference into EESS passive sensors from ARNS depending on the number of radio altimeters in view but that up to 5% random loss of data is permissible without compromising the overall measurements of the EESS (passive),

recognizing

that the use of the band by ARNS is for safety of life purposes and that the use and development of the band by ARNS should not be constrained,recommends

1 that sharing, between passive sensors in the Earth exploration-satellite service used for monitoring sea surface temperatures and airborne radio altimeters in the aeronautical radionavigation service, is feasible in the 4 200-4 400 MHz band based on characteristics given in Annex 1 and the sharing study in Annex 2 taking into account considering h) and the recognizing above;


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2 that in scanning coastal regions where airports are located, radiometers employ “Forward Looking” antennas with a look angle of [55] with respect to nadir to reduce the potential of interference from airborne altimeters.

ANNEX TO DOCUMENT 7C/TEMP/2(Rev.1)

Characteristics of a microwave radiometer

The following characteristics are based on a typical advanced microwave scanning radiometer:

Frequency band 4 200-4 400 MHzOrbital height 803 kmAntenna type Forward looking (55 with respect to Nadir) conical scanningScan angle 61Antenna size 3 mAntenna beamwidth 1.8Mainbeam gain 40 dBiSide lobe gain -15 dBiPermitted interference level -158 dBW/200 MHz (Recommendation ITU-R SA.1029)

Characteristics of altimeters in the aeronautical radionavigation service

Frequency 4 GHzTransmitter power (CW) -2 dBWTransmitter power (pulse) -1 dBW (Tx power: 200 W, PRF: 18 kHz, Pulse width: 200 ns)Antenna type Patch antennaAntenna gain 10 dBiAntenna beamwidth 70 degree Antenna backlobe level -30 dBi (without platform)Shielding effect -5 dB

NOTE 1 – A pulse power of -1 dBW was used in the sharing analysis.

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Part 10Liaison statement to working party 8D concerning the protection of radar in the band 1215 - 1300 MHz (ITU-R Document 8D/49-E).


This paper is based on on Document 8B/TEMP/26, produced by the October 2000 meeting of WP8B. Information on the protection requirements of radar station in the band 1215 - 1300 MHz is necessary in order to enable working party 8D to continue its work on the need (and value) of a pfd limit for the radionavigation satellite service. (See also comments on 8B/TEMP/6 re. WRC agenda item 1.15 and report of working party 8D). It further indicates that ITU-R Recommendations ITU-R M.1317, 1088 and 1477 provides information on this matter.

AMCP WGF Action: Comments are required on the application of a protection requirement of I/N of 10 dB and the radar radiation patterns.


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Source: Documents 8B/TEMP/26

Working Party 8B

COMMENTS ON THE LIAISON STATEMENT FROM WORKING PARTY 8D CONCERNING THE PROTECTION OF RADAR IN THE BAND 1 215-1 300 MHz

Working Party 8B takes note of the liaison statement from WP 8D (source: Document 8D/TEMP/5) concerning Resolution 606 (WRC-2000) which invites to conduct, as a matter of urgency and in time for WRC-03, the appropriate technical, operational and regulatory studies, including an assessment of the need for a power flux-density limit concerning the operation of radionavigation-satellite service (space-to-Earth) systems in the frequency band 1 215-1 300 MHz in order to ensure that the radionavigation-satellite service (space-to-Earth) will not cause harmful interference to the radionavigation and the radiolocation services, considering that in the band 1 215-1 260 MHz radionavigation-satellite service (space-to-Earth) systems have been successfully operated for a considerable time.WP 8D requests WP 8B to provide radar characteristic information, in particular the interference threshold in the band 1 215-1 300 MHz. WP 8D also wishes to refer WP 8B to Recommendations ITU-R M.1317, ITU-R M.1088 and ITU-R M.1477.

Concerning radar characteristic information, Working Party 8D could usefully take the characteristic of and protection criteria for radars operating in the radiodetermination service in the frequency band 1 215-1 400 MHz that have been inserted in Recommendations ITU-R M.1463 and ITU-R M.1227.Nevertheless, more elements must be taken in consideration to conduct sharing studies:– The interference criteria given in Recommendation ITU-R M.1463 is currently under

discussion, and could be further adjusted. Several administrations have proposed a protection criteria of I/N = –10 dB.

– More information concerning radar radiation patterns could be needed for RNSS sharing studies. This additional information is presently not included in Recommendation ITU-R M.1463, and WP 8B requested WP 8D to provide more details of the type of information required.

– Resolution 606 acknowledges the fact that there is presently no harmful interference between RNSS, radionavigation and radiolocation services in the band 1 215-1260 MHz, in which RNSS systems, described in Recommendations ITU-R M.1317, ITU-R M.1088 and ITU-R M.1477, are already in function.

These facts seem to indicate that the data given in Recommendations ITU-R M.1317, ITU-R M.1088 and ITU-R M.1477 could be used in WP 8D, in a first stage, to take into account operational experience in preparing the response to Resolution 606 (WRC-2000).

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Document 8D/49-E25 October 2000English only