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NONRESIDENT
TRAINING COURSE
Information Systems Technician Training Series Module 4—Communications Hardware NAVEDTRA 14225A
PREFACE About this course: This is a self-study course. By studying this course, you can improve your professional/military knowledge, as well as prepare for the Navywide advancement-in-rate examination. It contains subject matter about day-to-day occupational knowledge and skill requirements and includes text, tables, and illustrations to help you understand the information. An additional important feature of this course is its references to useful information to be found in other publications. The well-prepared Sailor will take the time to look up the additional information. Any errata for this course can be found at https://www.advancement.cnet.navy.mil under Products. Training series information: This is Module 4 of a series of 5. For a description of the entire series, see NAVEDTRA 12061, Catalog of Nonresident Training Courses, at https://www.advancement.cnet.navy.mil. History of the course: • Sep 1997: Original edition (NAVEDTRA 14225) released. • Apr 2003: Revised edition (NAVEDTRA 14225A) released.
Published by NAVAL EDUCATION AND TRAINING
PROFESSIONAL DEVELOPMENT AND TECHNOLOGY CENTER
https://www.cnet.navy.mil/netpdtc
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TABLE OF CONTENTS
CHAPTER PAGE
1. Communications Hardware ................................................................................... 1-1
2. Satellites and Antennas .......................................................................................... 2-1
APPENDIX
I. Glossary ................................................................................................................. AI-1
II. Glossary of Acronyms and Abbreviations ............................................................. AII-1
III. References Used to Develop this NRTC ............................................................... AIII-1
INDEX ................................................................................................................................ INDEX-1
Course assignments follow the index.
CHAPTER 1
COMMUNICATIONS HARDWARE
LEARNING OBJECTIVES
The high-paced operations required of modernfleet units demand communication systems that arecapable of providing high-speed, accurate, and securetransmission and reception of intelligence. To keeppace with the ever-increasing complexity ofoperations, today’s communication systems arenecessarily highly sophisticated and versatile. For ourships and submarines to operate effectively, whetherindependently or as part of a battle group, they musthave communication systems and operators that arecapable of meeting this challenge.
In this chapter, we will discuss various aspects offleet communication systems. As an InformationSystems Technician (IT), you will be responsible forknowing the different communication systems used bythe Navy and what communication equipments makeup a system.
COMMUNICATIONS SYSTEMS
Through equipment design and installation, manyequipments are compatible with each other and can beused to accomplish various functions. Using thisdesign concept, nearly all the communication needs ofa ship can be met with fewer pieces of communicationsequipment than were previously required.
Communications can be maintained at the highestpossible state of readiness when all levels of commandunderstand the capabilities and limitations of thesystems. Many communications failures areattributable to poor administration rather than toequipment failure or technical problems.
In this section, we will discuss predeploymentreadiness; low-, high-, very-high-, ultra-high-, andsuper-high-frequency communications systems; andequipment components that comprise these systems.
UNDERWAY PREPARATION
Ships deploying to overseas areas must be in a stateof maximum operational and communicationsreadiness. Type commanders determine the level ofreadiness of deploying ships and ensure they areadequately prepared.
A check-off list is an excellent method to ensurethat step-by-step preparations are completed before adeployment. This list should cover all aspects ofcommunications readiness and should begin well inadvance of the underway period. Some of the points tobe checked include scheduling of communicationsassistance team (CAT) visits, maintenance andoperational checks of equipment and antennas, andconsumable supply levels.
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Upon completing this chapter, you should be able to do the following:
• Determine the equipment required for each communications system.
• Identify the hardware setup procedures for radio systems.
• Identify the use of COMMSPOTS.
• Identify procedures and requirements for communications equipment as it
pertains to OTAR/OTAT functions.
• Determine utilization, frequencies, and watches needed for distress
communication equipment.
• Interpret how to monitor circuit quality equipment.
The Basic Operational Communications Doctrine(U), NWP 4, provides suggested minimum check-offsheets, including a predeployment check-off sheet anda preunderway check-off sheet. The first sheetprovides a timetable of required checks and objectives.The second sheet is tailored to individual ships andunique requirements.
LOW-FREQUENCY SYSTEMS
The low-frequency (LF) band (30-300 kHz) isused for long-range direction finding, medium- andlong-range communications, aeronautical radionavigation, and submarine communications.
A low-frequency transmitter, such as theAN/FRT-72, is used to transmit a high-powered signalover long distances. Low-frequency transmitters arenormally used only at shore stations or for specialapplications.
The low-frequency receive system is designed toreceive low-frequency broadcast signals and toreproduce the transmitted intelligence.
HIGH-FREQUENCY SYSTEMS
The high-frequency (HF) band (3-30 MHz) isprimarily used by mobile and maritime units. Themilitary uses this band for long-range voice andteleprinter communications. This band is also used as abackup system for the satellite communicationssystem. Figure 1-1 shows a common HF transmitterand figure 1-2 shows a common HF receiver.
VERY-HIGH-FREQUENCY SYSTEMS
The very-high-frequency (VHF) band (30-300MHz) is used for aeronautical radio navigation andcommunications, radar, amateur radio, and mobilecommunications (such as for boat crews and landingparties).
ULTRA-HIGH-FREQUENCY SYSTEMS
The ultra-high-frequency (UHF) band (300-MHzto 3-GHz) is used for line-of-sight (short-range)communications. The term “line of sight,” as used incommunications, means that both transmitting andreceiving antennas must be within sight of each otherand unaffected by the curvature of the Earth for propercommunications operation.
The UHF band is also used for satell i tecommunications. Although satellite communicationsare line of sight, the distance the signal travels is muchgreater than that of UHF surface communications,because the antennas remain in sight of each other.
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Figure 1-1.—HF transmitter AN/URT-23-D.
Figure 1-2.—Receiver R-2368-URR HF.
As in the VHF section, the transmit and receivesystems will be described separately.
SUPER-HIGH-FREQUENCY SYSTEMS
The super-high-frequency (SHF) band (3-30 GHz)is strictly for line-of-sight communications. It isconfigured much the same as the UHF system. SHF ismainly used for satellite communications. SHFsatellite communications is a high-volume system thatoffers reliable tactical and strategic communicationsservices to U.S. Navy elements ashore and afloat. Thesystem is composed of the terminal segment,consisting of U.S. Navy-operated Earth terminals andmobile terminals. It also includes a portion of theDefense Satellite Communications System (DSCS)satellite segment. Navy Super-High FrequencySatellite Communications, NTP 2, Section 1 (C),provides comprehensive coverage of the Navy SHFsatellite system.
EXTREMELY-HIGH-FREQUENCYSYSTEMS
The extremely-high-frequency (EHF) band(30-300 GHz) provides the services with interoperableand survivable SATCOM. In terms of capabilities,operations, and management, EHF SATCOM isconsiderably different from the UHF and SHFSATCOM systems. However, like other systems, theEHF satellite system consists of three segments: thespace segment, control segment, and terminalsegment. All segments have been designed to counterjamming, intercept, spoofing, and nuclear effects. Thesystem uses a combination of directional antennas andadvanced signal processing techniques to achievesignificantly improved anti-jam (AJ) and lowprobability of intercept performance over existingUHF and SHF SATCOM systems.
PATCH PANELS
Patch panels are used for the interconnection andtransfer of radio signals and equipment aboard ship.
Patch panels are red (fig. 1-3) or black (fig.1-4) toidentify secure and nonsecure information. Redindicates that secure (classified) information is beingpassed through the panel. Black indicates thatnonsecure (unclassified) information is being passedthrough the panel. Both panels are also labeled withsigns. The red panel sign has 1-inch-high white blockletters that read “RED PATCH PANEL.” The blackpanel normally has two black signs containing
l-inch-high white block letters. One sign reads“BLACK PATCH PANEL” and the other, “UNCLASONLY.” In some instances, commonly usedcombinations of equipment are permanently wiredtogether within the panel (called normal-through).
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Figure 1-3.—Red patch panel (SA-2112).
Figure 1-4.—Black patch panel (SB-983).
CRYPTOGRAPHIC EQUIPMENT
Some of the systems in the previous figurescontained cryptographic equipment. Cryptographicequipment is only one of a number of the elements thatmake up a secure communications system. Thoughseveral different types of on-line crypto equipmentsare in use throughout the naval communicationssystem, they are all designed to perform the same basicfunction: to encipher and decipher teleprinter or digitaldata signals.
Simply stated, the transmitter accepts a “plaintext” teleprinter or data signal containing classifiedmaterial from the classified patch panel (red). It thenadds a “key,” and relays the sum as “cipher text,” or anenciphered signal. A key is a sequence of randombinary bits used to initially set and periodically changepermutations in crypto equipment for decryptingelectronic signals.
Following this encryption, the signal is fed to theunclassified patch panel (black). Here, it is patcheddirectly to the frequency-shift keyer (FSK) or themultiplex equipment of the transmitter and convertedinto an audio signal. The audio signal, now in a formsuitable for transmission, is routed to the transmittervia the transmitter transfer switchboard.
On the receive side, the signal flow is quite similarto the send side in reverse order. The receiver acceptsthe enciphered signal from the black patch panel andgenerates a key to match the one generated by thetransmitter. The receiver then subtracts the key fromthe cipher text input (which restores the plaintextteleprinter or data signal). Finally, it passes the signalon to the red patch panel for dissemination to theterminal equipment for printout.
For further information and operator instructionson a specific type of crypto equipment, refer to theapplicable KAO publication.
SHIP-SHORE CIRCUITS
As we mentioned earlier, the fleet broadcast is theprimary means for delivering messages to afloatcommands. This section discusses a few of the othertypes of circuits by which a ship can transmit itsmessage traffic ashore or to other ships for delivery orrelay.
SHIP-SHORE CIRCUIT MODES OFOPERATION
The three methods of operating communicationscircuits are duplex, simplex, and semiduplex. Themode of operation at any given time depends uponequipment and frequency availability.
Duplex
Duplex describes a communications circuitdesigned to transmit and receive simultaneously. Insuch operations, each station transmits on a differentfrequency and both stations transmit concurrently.Both stations are required to keep transmitters on theair at all times and to send a phasing signal at therequest of the distant end.
The two types of duplex operation are full duplexand half duplex. Full duplex (FDX) refers to acommunications system or equipment capable oftransmitting simultaneously in two directions. Halfduplex (HDX) pertains to a transmission over a circuitcapable of transmitting in either direction, but only onedirection at a time.
Small ships traveling in company normally useduplex in a task group common net in which theyterminate with a larger ship that is serving as netcontrol. The net control ship provides the ship-shorerelay services. Ships traveling independently can usethis system for a non-call ship-shore termination totransmit their outgoing messages.
Simplex
Simplex is a method of operation that provides asingle channel or frequency on which information canbe exchanged. Simplex communications operation isnormally reserved for UHF and those ships that do nothave sufficient equipment for duplex operation. Insome cases, a simplex circuit can be established whenequipment casualties occur.
Where no HF simplex frequency is indicated orguarded, ships requiring a simplex ship-shore circuitmust call on a duplex ship send frequency. The shipmust state “SIMPLEX” in the call-up, indicating thatthe ship cannot transmit and receive simultaneously.
When a ship requests simplex operation on duplexcircuits, the shore station may be required to shifttransmitters before acknowledging call-up. If no reply
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is received within 45 seconds, the ship should repeatthe call-up procedures. If a third attempt is required,the ship should check equipment to ensure properoperation.
Semiduplex
Semiduplex communications circuits, usedprimarily on task force/task group/ORESTES, are acombination of the simplex and duplex modes. Allstations except the net control station (NECOS)transmit and receive on the same frequency. TheNECOS transmits and is received on a secondfrequency. The NECOS may transmit continuously,whereas all other stations must transmit in accordancewith simplex procedures.
UHF/HF RELAY
The UHF/HF relay method permits long-range,uninterrupted communications during periods ofhazardous electromagnetic radiation (HERO).
Modern radio and radar transmitting equipmentsproduce high-intensity RF fields. It is possible for RFenergy to enter an ordnance item through a hole orcrack in its skin or to be conducted into it by firingleads, wires, and the like. Here is an example of HERO.An aircraft carrier is arming aircraft on board. Duringarming operations, all HF transmitters must be securedto prevent possible detonation of the ordnance. Tomaintain its ship-shore communications, the carriertransmits to a relay ship via a UHF circuit. The relayingship then retransmits the signal on an HF circuit to aterminated NAVCOMTELSTA. On-line radioteleprinters can be relayed, as well as voice, using thiscircuit.
SECURE VOICE WORLDWIDE VOICENETWORK
The secure voice network is designed to providereal-time voice communications between forces afloatand operational commanders ashore, using either HFor satellite connectivity. This system is commonlyreferred to as GPS Worldwide HICOMM.
System Control
This system consists of three separate networks.Each network has an area control station controlled bya FLTCINC; CINCLANTFLT, CINCPACFLT, orCINCUSNAVEUR. Each area has subarea control
stations determined by each FLTCINC to ensureworldwide coverage.
Satellite System Control
The secure voice system, using satell i tetransmissions, has limited shore access points at thefour COMMAREA master stations. These sites serveas the interface channel to both the wideband andnarrowband voice systems to extend calls tooperational commanders ashore.
Net Membership
If a ship, aircraft, or shore station needs to enter thesecure voice network, it must be prepared to do so withminimum time delay. Units desiring to enter the net ona temporary basis must specify the length of time andpurpose for entering the net. They must also obtainpermission from the appropriate control station. Thearea net control station (NECOS) is responsible forcompleting all calls originating from senior commandsto all commands, ships, or aircraft within the specificFLTCINC’s net. Certain rules must be observed whenon the secure voice net, as follows:
• HF transmitter tuning is prohibited on securevoice. Transmitters must be calibrated andpretuned on a dummy load. Final tuning may beaccomplished during live transmissions.
• All stations must maintain a continuous log-onsecure voice. The actual time of significanttransmissions must be entered into the log.When available, recording devices must be usedin lieu of a paper log.
• The net operates as a free net unless otherwisedirected by the area FLTCINC. NECOS retainsthe prerogative of exercising control over alltransmissions to ensure proper circuit discipline.
FULL-PERIOD TERMINATIONS
Full-period terminations are dedicated circuits thatprovide communications between shore stations andafloat commands. These terminations requireallocation of limited NCTAMS/NCTS assets.Therefore, the criteria for requesting, approving, andestablishing such circuits is necessarily strict.
Termination Requests
Afloat commands and individual units can requestfull-period termination during special operations,deployments, intensive training periods, or exerciseswhen primary ship-shore circuits will not suffice.
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Commands should request full-period terminationsonly when traffic volume exceeds speed and capabilityof ship-shore circuits and when operational sensitivityrequires circuit discreetness or effective command andcontrol necessitates dedicated circuits.
The heavy demands placed upon NCTAMS/NCTSs for full-period terminations require maximumcooperation between shore stations and afloatcommanders before and during an operation. Shipshaving a need for a full-period termination, either fortraining or operational requirements, must submit atermination request to the COMMAREA masterstation at least 48 hours before activation time.
Emergency commitments or a command directivemay necessitate a lead time of less than 48 hours.Whenever possible, however, the 2-day limit must behonored to achieve maximum preparation andcoordination. NTP 4 gives details of requiredinformation that must be included in a terminationrequest message.
The COMMAREA master station will assign ashore station for a ship’s termination circuit. Once theshore station has been assigned, both the ship and thestation may begin coordination to identify specificequipment keylists and frequencies needed to effecttermination. The shore station will also act as NECOS.Two hours before the scheduled termination, the shorestation can coordinate with the ship by telephone, localcircuitry, or by primary ship-shore.
When the ship shifts terminations, the securing ofthe current termination and the establishment of a newtermination should coincide with a broadcast shiftwhenever possible. The ship must submit aCOMMSHIFT message.
Termination Types
The six types of full-period terminations are asfollows:
• Single-channel radio teleprinter using eitherradio path or landline transmission media;
• Single-channel low-data-rate satellite accessusing satellite transmission media;
• CUDIXS special satel l i te access forNAVMACS-equipped ships using satellitetransmission media;
• Multichannel radio teleprinter using either radiopath or landline transmission media;
• Multichannel radio teleprinter using SHFsatellite transmission media; and
• Tactical intelligence (TACINTEL) access forTACINTEL-equipped ships using satellitetransmission media.
Equipment Tests
To ensure that circuit equipment is in peakoperational condition, complete system back-to-backoff-the-air tests must be completed 24 hours beforetermination activations. Check crypto equipmentback-to-back after daily crypto changes and beforeputting circuits into service.
An aggressive PMS and quality monitoringprogram is essential. When checking equipment, lookfor power levels, scorch or burn marks, properoperation of interlocks, and cleanliness. Whencleaning and inspecting antennas, look for cracks,chips, or blistering of insulators. Also check fordeterioration, loose connectors, and correct insulatorresistance.
COMMSPOT Reports
COMMSPOT reports will be submitted by allships, including nonterminated units, any time unusualcommunication difficulties are encountered. Shipswill submit the COMMSPOT to the terminatingcommunications station. Timely submission ofCOMMSPOT reports is necessary to minimize furtherdeterioration of the situation.
Rules and general instructions for preparingJINTACCS formatted COMMSPOT reports are foundin the Joint Reporting System (General-PurposeReports), NWP 1-03, Supp-1 (formerly NWP10-1-13).
PRIMARY SHIP-SHORE CIRCUITS
Primary ship-shore (PRI S/S) circuits areencrypted FSK/PSK teleprinter nets that permit shipsto transmit messages for delivery ashore. This serviceis available to units that do not maintain a full-periodship-shore termination. Navy tactical UHF satellites orthe HF/UHF spectrum may be used to conductship-shore circuit operations. Ships may use thiscircuit for coordinating and establishing a full-periodtermination with the shore station.
The frequencies for NCTAMS andNAVCOMTELSTAS that guard primary fleet
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ship-shore circuits are listed in applicable CIBsdistributed by the COMMAREA master stations.These frequencies are subject to change by thecognizant FLTCINC or by the NCTAMS.
OVER-THE-AIR TRANSFER (OTAT) ANDOVER-THE-AIR REKEY (OTAR)
Significant vulnerabilities are associated with thehandling of paper cryptographic material. Soundappl ica t ion of over- the-a i r t ransfer / rekey(OTAT/OTAR) procedures and techniques can reducethe amount of paper keying material required andreduce the potential for compromise. Theseprocedures and techniques are contained in theNAG-16B Procedures Manual for Over-the-AirTransfer (OTAT) and Over-the-Air Rekey (OTAR).
OTAT/OTAR also makes the transfer of keyingmaterial more responsive to rapidly changingoperational requirements. The use of NAG-16B wasdeveloped and verified by extensive use duringoperation Desert Shield/Storm. The specifiedprocedures served as an effective vehicle fortransferring keying to satisfy rapidly changing jointand Navy requirements. Expanded definitions, generalprocedures, and equipments are found in NAG-16B.
DISTRESS COMMUNICATIONS
Special methods of communication have beendeveloped to use in times of distress and to promotesafety at sea and in the air. Distress message traffic isbest described as all communications relating to theimmediate assistance required by a mobile station indistress. Distress traffic has priority over all othertraffic. All U.S. Navy communicators must be familiarwith distress signals to properly evaluate theirmeanings and to take appropriate action whennecessary.
If a ship becomes involved in a distress situation,communications personnel should send distressmessages on normal operating encrypted circuits. Ifthe need for ass is tance outweighs secur i tyconsiderations, the ship’s commanding officer mayauthorize the transmission of an unclassified distressmessage on one of the national or international distressfrequencies.
When a ship in distress is traveling in companywith other ships, the ship in distress will transmit thedistress message to the officer in tactical command(OTC), who will take appropriate action.
DISTRESS FREQUENCIES
Several frequencies in different bands aredesignated for the transmission of distress, urgency,safety, or search and rescue (SAR) messages. Thefollowing frequencies have been designated for useduring a distress or emergency situation:
• 500 kHz—International CW/MCW distress andcalling;
• 2182 kHz—International voice distress, safety,and calling;
• 8364 kHz—International CW/MCW lifeboat,life raft, and survival craft;
• 121.5 MHz—International voice aeronauticalemergency;
• 156.8 MHz—FM United States voice distressand international voice safety and calling; and
• 243.0 MHz—Joint/combined military voiceaeronautical emergency and internationalsurvival craft.
During SAR missions, the following frequenciesare authorized for use:
• 3023.5 and 5680 kHz—International SARfrequencies for the use of all mobile units at thescene of a search. Also for use of shore stationscommunicating with aircraft proceeding to orfrom the scene of the search. CW and voice areauthorized.
• 123.1 MHz—International worldwide voiceSAR use.
• 138.78 MHz—U.S. military voice SARon-the-scene use. This frequency is also used fordirection finding (DF).
• 172.5 MHz—U.S. Navy emergency sonobouycommunications and homing use. Thisfrequency is monitored by all U.S. Navy ASWaircraft assigned to a SAR mission.
• 282.8 MHz—Joint/combined on-the-scenevoice and DF frequency used throughout NATO.
The control of distress message traffic on anydesignated frequency is the responsibility of the stationin distress. However, this station may delegate itsresponsibility to another station on the frequency.
Distress Watches
Navy units at sea have always maintained listeningwatches on distress frequencies. Communicationwatch requirements vary according to the operational
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mission of the ship and available equipment assets.Ships in company normally divide distress watchrequirements among the group.
STATUS BOARD
The technical control of the shore station that isNECOS for fill-period terminations and PRI S/Scircuits must maintain a status board. The status boardshould indicate, as a minimum, all systems/circuitsthat are active, tuned in, or in a standby status. It shouldalso indicate all inoperative equipment. The watchsupervisors must verify the accuracy of theinformation contained on the status board at watchturnover and update while on watch. The status boardmust show the following minimum information foractive and standby circuits:
• Functional title of circuit,
• Frequency(ies), both send/receive, if fill-duplexoperation is used,
• Circuit designator, from communication plan,
• Transmitter and receiver designations,
• For shore stations, keying line designations,
• Terminal equipment designation (for example,R-2368/URR #l),
• Crypto equipment, keying material, and restarttime,
• Operating position or remote control unitdesignation; and
• Remarks, as appropriate.
QUALITY MONITORING
In recent years, the volume of communications hasincreased dramatically. This rapid expansion has led tothe installation of increasingly sophisticatedequipment. Such factors as frequency accuracy, dcdistortion, inter-modulation distortion (IMD), anddistribution levels are critical to the operation ofcommunications systems.
Satisfactory operation of these systems demandsprecise initial line-up and subsequent monitoring.System degradation is often caused by many smallcontributing factors that, when combined, render thesystem unusable. Simply looking at the page printer orlistening to the signal is inadequate.
Simply stated, quali ty monitoring is theperformance of scheduled, logical checks that will
ensure continuous, optimum performance and, inmany cases, prevent outages before they occur. Somecommunications personnel quite often fail to realizethe benefits of quality monitoring. An attitudedevelops that questions the need for qualitymonitoring. The result of this incorrect attitude is thatcircuits are either UP or DOWN. Personnel with thisattitude perform no quality monitoring when thecircuits are UP and are, therefore, forced to treat eachoutage as if it were a unique occurrence.
With no precise information concerning the trendof the system’s performance, personnel must jumpfrom one assumed probable cause to another assumedprobable cause, while valuable circuit time is lost. Aship with an aggressive quality monitoring programusually has personnel who are thoroughly familiarwith all installed communications systems.
QUALITY MONITORING PROGRAM
The primary function of the quality monitoringprogram is the direct measurement of signal qualitycharacteristics, including:
• Dc distortion,
• Audio distribution level,
• Frequency accuracy of RF signals,
• Spectrum analysis, and
• Loop current.
These measurements are broad categories and canbe broken down to specific tests for specific systems.
Quality Monitoring System
Figure 1-5 is a diagram of a quality monitoringsystem and RCS interface. The system was designed toprovide a means of monitoring and evaluatingperformance of any communications system used byforces afloat.
The monitoring system is a grouping of specifictest equipments into a console designated as theAN/SSQ-88 Quality Monitoring Set (fig. 1-6). The setcontains equipment for measuring and analyzingsignals sampled by sensors installed in eachcommunications circuit interface. The system shouldbe operated only by personnel with sufficientknowledge to analyze the signals being transmittedand received via the ship’s circuits, includingindividual channels of the multichannel circuits.
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1-9
RCS AN/SSQ-88/A/B
EXTERNAL CABLETERMINATION CABLE
BLACK DC P/P
BLACK DC P/P
(NOTE)
SEND
AN/WSC-3
RECEIVE
10 MHZ FREQ STD
UHF ANTENNA
OPTION 1*
OPTION 2*
OPTION 3*
AN/WSC-3 70 MHZ IF
TO ANT RCVR P/P
to xmtr p/p
to xmtr p/p
to rcvr p/p
to rcvr p/p
5 MHZ FREQ STD
AC PWR DIST
TELEGRAPHDISTORTION
TEST SET
OSCILLOSCOPE
DC PATCH PANEL
SPECTRUM ANALYZER
RF PATCH PANEL
TRACKING GENERATOR
AUDIO PATCH ANDTERMINATION PANEL
SIGNAL GENERATOR
SPEAKER PANEL
1A1
1A2
1A3
1A4
1A5
1A6
1A7
1A8
1A9
EXTERNAL
TERMINATION
PANEL
1A10
SIGNAL
ASYNCH
TRIG
(NOTE) Not used in Dual DAMA installation.
OPTIONS: 1: AN/SSQ-88() has its own dedicated HF Antenna.2: AN/SSQ-88() shares the 2-32 MHz Antenna dedicated to
AN/SRA-49 by use of a Bi-Directional Coupler.3: AN/SSQ-88() shares the antennas for the AN/SRA-38/AN/SRA-39
and AN/SRA-40 to obtain frequency coverage of 2-32 MHz by use ofa Bi-Directional Coupler.
ITf01005
(IF AVAILABLE)
Figure 1-5.—AN/SSQ-88 Quality Monitoring Set and RCS interface.
The console configuration shown in figure 1-6may not be compatible with all ships; however, mostships can use equivalent test equipment to establish aquality monitoring test system.
SUMMARY
Your commanding officer must be able tocommunicate with ships and shore stations to maintaineffective command and control of the situation at hand.Communications are, and always will be, the “voice ofcommand.” In the age of nuclear weapons, guidedmissiles, supersonic aircraft, and high-speed ships andsubmarines, top performance is required of our fleetcommunicators. You, as an IT, along with yourequipment, must always be in constant readiness tomeet this formidable challenge.
Distress communications are methods that have
been developed for use in times of distress. They
indicate the need for immediate assistance and
have priori ty over al l other traffic . Various
publications and local instructions will assist you in
carrying out your required responses to these
situations.
Communication systems are periodically tested to
ensure that they operate efficiently and accurately. The
combined tests, checks, and measurements help
determine the condition of systems, subsystems, and
individual equipments. Tests and measurements of
communication systems and equipments range from
the very simple to the very complex.
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Figure 1-6.—AN/SSQ-88 equipment configuration.
CHAPTER 2
SATELLITES AND ANTENNAS
LEARNING OBJECTIVES
Satellite communication (SATCOM) systemssatisfy many military communications requirementswith reliable, high-capacity, secure, and cost-effectivetelecommunications. Satellites provide a solution tothe problem of communicating with highly mobileforces deployed worldwide. Satellites also provide analternative to large, fixed ground installations. Theyprovide a lmost ins tan taneous mi l i ta rycommunications throughout the world at all but thehighest latitudes (above 700).
TYPES OF SATELLITES
Three types of communications satellites are in useby the U.S. Navy today. They are GAPFILLER, FleetSatellite Communication (FLTSATCOM), and LeasedSatellite (LEASAT) (figure 2-1). These satellites are ingeosynchronous orbit over the continental UnitedStates and the Atlantic, Pacific, and Indian oceans.Each satellite is described in the following paragraphs.
GAPFILLER
In 1976, three satellites, called MARISAT, wereplaced into orbit over the Atlantic, Pacific, and Indianoceans. Each satellite had three UHF channels formilitary use, one wideband 500-kHz channel, and twonarrowband 25-kHz channels.
The Navy leased the UHF section of each satellitefor communications purposes. To distinguish thespecial management and control function forcommunications on these UHF channels, the Navygave the name GAPFILLER to the leased satelliteassets.
GAPFILLER was intended to fill the need for acontinuing satellite communications capability insupport of naval tactical operations until the Navyachieved a fu l ly operable Flee t Sate l l i teCommunications (FLTSATCOM) system.
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Upon completing this chapter, you should be able to do the following:
• Identify the theory relating to satellites.
• Calculate azimuth and elevation using plotting guides.
• Identify the types, basic system and fleet broadcast subsystem equipment ofcommunication satellites.
• Identify the characteristics of antennas and antenna selections.
• Identify the types of antennas.
• Explain how the distribution systems interface with antenna assignment andselections.
• Identify the procedures for setting up antenna couplers, multicouplers,transmitters, and transceivers.
• Explain how the patch panel is used in conjunction with the equipment.
• Identify the procedures for raising and lowering antennas.
• Determine the optimum reception of a directional antenna by rotation, alignment,and tuning.
• Identify safety precautions that should be observed when working on antennas.
The GAPFILLER satellite over the Indian Oceanis the only one still being used by the U.S. Navy. Theother two GAPFILLER satellites were replaced byLEASAT. The active GAPFILLER satellite will alsobe replaced by LEASAT as it reaches the end of itsoperational life.
Within the 500-kHz band, transponders provide 20indiv idual 25-kHz low- and high-da ta- ra tecommunications channels for 75-baud ship-shorecommunications and for the automated informationexchange systems. The UHF receiver separates thereceive band (302 to 312 MHz) from the transmit band(248 to 258 MHz).
The receiver translates the received carriers tointermediate frequencies (IFs) in the 20-MHz rangeand separates them into one of three channels. Onechannel has a 500-kHz bandwidth, and two have abandwidth of 25 kHz each. The signals are filtered,
hard limited, amplified to an intermediate level, andup-converted to the transmit frequency. Each channel isthen amplified by one of three high-power transmitters.
GAPFILLER also supports the FLTSATCOMsystem secure voice system and the fleet broadcast inthe UHF range. The GAPFILLER communicationssubsystem will eventually be replaced by theFLTSATCOM system.
FLTSATCOM
There are four FLTSATCOM satellites in service.These satellites are positioned at 100° W, 72.5° E, 23°W, and 172° E longitudes. They serve the Third, Sixth,Second, and Seventh fleets and the Indian Ocean battlegroups. These four satellites provide worldwidecoverage between 70° N and 70° S latitudes (figure2-2).
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Figure 2-1.—GAPFILLER, FLTSATCOM, and LEASAT satellites.
Each FLTSATCOM satellite has a 23-RF-channelcapability. These include 10 25-kHz channels, 125-kHz channels, and 1 500-kHz channel. The 500-kHzand the 10 25-kHz channels are reserved for Navy use.Of the 10 25-kHz channels, channel 1 is used for thefleet broadcast. All channels use SHF for the uplinktransmission. SHF is translated to UHF for thedownlink transmission.
There is a separate UHF downlink transmitter foreach channel. Each of the 23 channels has 3 differentfrequency plans in which the uplink or downlink maybe transmitted. This capability precludes interferencewhere satellite coverage overlaps.
LEASAT
The latest generation of Navy communicationssatellites is leased; hence, the program name LEASAT.As we mentioned earlier, these satellites replaced 2 ofthe 3 GAPFILLER satellites and augment theFLTSATCOM satellites.
CONUS LEASAT (L-3) is positioned at 105° Wlongitude, LANT LEASAT (L-1) is positioned at 15°W longitude, and 10 LEASAT (L-2) is positioned at72.5° E longitude (figure 2-3).
Each LEASAT provides 13 communicationschannels using 9 transmitters. There are 7 25-kHz
UHF downlink channels, 1 500-kHz widebandchannel, and 5 5-kHz channels. The 500-kHz channeland the 7 25-kHz channels are leased by the Navy. Oneof the 25-kHz UHF downlink channels is the downlinkfor the Fleet Satellite Broadcast.
The broadcast uplink is SHF, with translation toUHF taking place in the satellite. The remaining625-kHz channels function as direct-relay channelswith several repeaters. Currently, the LEASATchannels provide for the following subsystems:
• Channel 1 for Fleet Satellite Broadcasttransmissions;
• 1 25-kHz channel for SSIXS communications;
• 1 25-kHz channel for ASWIXS communica-tions; and
• 2 25-kHz channels for subsystems that transmitor receive via DAMA (Demand AssignedMultiple Access) (for example, CUDIXS/NAVMACS, TACINTEL, and secure voice).
SHF SATCOM
Operations Desert Shield/Desert Storm reinforcedthe requirement for and greatly accelerated theintroduction of SHF SATCOM capability on aircraftcarriers and amphibious flagships to satisfy minimum
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Figure 2-2.—FLTSATCOM coverage areas.
tactical command and control (C2), intelligence andwarfighting communications requirements whileimproving Joint and NATO/Allied communicationsinteroperability. To meet the urgent operationalrequirement, the U.S. Navy obtained and modifiedU.S. Air Force AN/TSC-93B Ground Mobile Forces(GMF) SHF SATCOM vans for installation on aircraftcarriers and amphibious flagships deploying to thePersian Gulf. The modified vans were coupled with theAN/WSC-6(V) standard U.S. Navy SHF stabilizedantenna system, the SURTASS modem, 2 low-speedtime division multiplexer (LSTDMs), and additionalpatch panels. The modified SATCOM terminals weredesignated “QUICKSAT.” The initial introduction ofthese terminals into the fleet officially marked thebeginning of the U.S. Navy’s SHF SATCOM fieldingplan.
The U.S. Navy also deployed an SHF DemandAssigned Multiple Access (DAMA) modem. Thisaction replaced the QUICKSAT terminals on aircraftcarriers, and adds SHF SATCOM capabilities to moreships.
In FY97, the U.S. Navy deployed the AN/WSC-6variant. The new terminal is a modem, modular, openarchitecture terminal capable of providing a full
spectrum of SHF SATCOM services and greatlyexpands the number of installations.
The system configuration that supports Navy SHFSATCOM consists of an SHF RF terminal andsupporting baseband equipment. The RF terminals forshipboard use are the AN/WSC-6(V) or AN/TSC-93B(MOD) “QUICKSAT” terminal. The terminals processand convert the RF signal transmitted to or receivedfrom the space segment. The transmit frequency rangeis 7.9 to 8.4 GHz, and the receive range is 7.25 to 7.75GHz. The OM-55(V)/USC AJ modems, 1105A/1106time division multiple access (TDMA)/DAMAmodem, and the CQM-248A (phase shift keying (PSK)modems) are deployed on shipboard platforms.
The AN/WSC-6(V) and QUICKSAT configuredterminals are compatible with present and futureDSCS SHF satellite ground terminals and consist of anantenna group, radio set group, and modem group. Theantenna group is configured as either a dual or singleantenna system. The AN/WSC-6(V)1, with theMD-1030A(V) modem, is used on SURTASS shipsequipped with a single antenna. The AN/WSC-6(V)2,with the OM-55(V)/USC, Frequency DivisionMultiple Access (FDMA) or TDMA/DAMA modems,is used on both flag and flag-capable platforms and isconfigured with either a single or dual antenna. The
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Figure 2-3.—LEASAT coverage areas.
QUICKSAT terminal is configured with an FDMAmodem, single or dual antenna, and deployed onselected aircraft carriers and amphibious flagships.The AN/WSC-6(V) and QUICKSAT terminalsautomatically track the selected satellite, whilesimultaneously transmitting and receiving. An antennacontrol unit commands the antenna to search fortracking (beacon) signals from the satellite. Uponsatellite acquisition, tracking is accomplishedautomatically.
BASIC SATCOM SYSTEM
A satellite communications system relays radiotransmissions between Earth terminals. There are twotypes of communications satellites: active and passive.An active satellite acts as a repeater. It amplifiessignals received and then retransmits them back toEarth. This increases the signal strength at thereceiving terminal compared to that available from apassive satellite. A passive satellite, on the other hand,merely reflects radio signals back to Earth.
A typical operational link involves an activesatellite and two Earth terminals. One terminaltransmits to the satellite on the uplink frequency. Thesatellite amplifies the signal, translates it to thedownlink frequency, and then transmits it back toEarth, where the signal is picked up by the receiving
terminal. Figure 2-4 illustrates the basic concept ofsatellite communications with several different Earthterminals.
The basic design of a satellite communicationssystem depends a great deal on the parameters of thesatellite orbit. Generally, an orbit is either elliptical orcircular. Its inclination is referred to as inclined, polar,or equatorial. A special type of orbit is a synchronousorbit in which the period of the orbit is the same as thatof the Earth’s.
Two basic components make up a satellitecommunications system. The first is an installedcommunications receiver and transmitter. The secondis two Earth terminals equipped to transmit and receivesignals from the satellite. The design of the overallsystem determines the complexity of the componentsand the manner in which the system operates.
The U.S. Navy UHF/SHF/EHF combinedcommunications solution allows each system toprovide unique contributions to the overall navalcommunications needs.
The SHF spectrum is a highly desirable SATCOMmedium because it possesses characteristics absent inlower frequency bands: wide operating bandwidth,narrow uplink beamwidth, low susceptibility toscintillation, anti-jam (AJ), and high data rates.
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Figure 2-4.—Satellite communications systems.
Recognizing these characteristics, the U.S. Navydeveloped and installed shipboard SHF terminals.These attributes are discussed in the followingparagraphs.
Wide operat ing bandwidth permits highinformation transfer rates and facilitates spreadspectrum modulation techniques. Spread spectrummodulation is a particularly valuable technique forlessening the effects of enemy jamming. Althoughwide bandwidth permits both high informationtransfer rates and AJ capabilities when using theOM-55(V)/USC modem, it may not permit bothsimultaneously in the presence of jamming. Therefore,high information transfer rates will be significantlyreduced when jamming is encountered, permittingonly certain predetermined critical circuits to bemaintained.
Narrow uplink transmission beamwidth provides alow probability of intercept (LPI) capability. An uplinkLPI capability reduces the threat of detection andsubsequent location, but does not in and of itself denyenemy exploitation of those communications ifdetection is achieved. SHF frequencies are rarelyaffected by naturally occurring scintillation, makingSHF SATCOM a particularly reliable form ofcommunications.
A characteristic of SHF, favorable to flagships, isthe ability to communicate critical C4I for the userinformation in the presence of enemy jamming andwith due regard for enemy detection capabilities.SURTASS Military Sealift Command AuxiliaryGeneral Ocean Surveillance (T-AGOS) ships wereinitially equipped with SHF SATCOM, takingadvantage of the high information transfer ratecapability and LPI characteristics. Because of largeravailable bandwidths, inherent jam-resistance, andincreasing demands on limited tactical UHF SATCOMresources, additional applications for DSCS SHFSATCOM afloat are continually being investigated forthe fleet.
The radio group consists of a high-power amplifier(HPA) or medium-power amplifier (MPA), low-noiseamplifier (LNA), up-converter, down-converter, andfrequency standard. For transmit operations, theup-converter translates the modem’s 70 or 700megahertz (MHz) intermediate frequency (IF) to thedesired radio frequency. The signal is then passed tothe HPA or MPA and amplified to its authorized powerlevel. During receive operations, the LNA amplifiesthe received RF signal and sends it to the trackingconverter for antenna control and the down-converter
for translation to 70 or 700 MHz IF. This signal is thensent to the modem for conversion to digital data.System frequency stability is provided by a cesium orrubidium standard.
FLEET BROADCAST SUBSYSTEMEQUIPMENT
The SATCOM equipments that the Navy uses forthe fleet broadcast include the SATCOM broadcastreceiver (AN/SSR-1), the FLTSATCOM SHFbroadcast transmitter (AN/FSC-79), the standardshipboard transceiver (AN/WSC-3), the shore stationtransceiver (AN/WSC-5), and the basic airbornetransceiver (AN/ARC-143B). A brief description ofthese equipments is given in the next paragraphs.
The AN/SSR-1 is the Navy’s standard SATCOMbroadcast receiver system. This system consists of upto four AS-2815/SSR-1 antennas wi th anAM-6534/SSR-1 Amplifier-Converter for eachantenna, an MD-900/ SSR-1 Combiner-Demodulator,and a TD-1063/SSR-1 Demultiplexer (figure 2-5). Theantennas are designed to receive transmissions at 240to 315 MHz. The antennas and antenna converters aremounted above deck so that at least one antenna isalways in view of the satellite. The combiner-demodulator and demultiplexer are mounted belowdeck.
The AN/FSC-79 Fleet Broadcast Terminal (figure2-6) interfaces the communications subsystems andthe satellite. The terminal provides the SHFuplink for the FLTSATCOM system and is usedin particular to support the Navy Fleet Broad-cast system. The AN/FSC-79 operates in the 7-to 8-GHz band and is designed for single-channeloperation. The AN/FSC-79 terminal is installedat the four COMMAREA master stations andNAVCOMTELSTA Stockton, Calif.
The AN/WSC-3 Transceiver is the standard UHFSATCOM transceiver for both submarine and surfaceships. The AN/WSC-3 is capable of operating in eitherthe satellite or line-of-sight (LOS) mode and can becontrolled locally or remotely.
The unit is designed for single-channel,half-duplex operations in the 224-to 400-MHZ UHFband. It operates in 25-kHz increments, and has 20preset channels. In the SATCOM mode, theAN/WSC-3 transmits (uplinks) in the 292.2- to311.6-MHz bandwidth and receives (downlinks) in the248.5- to 270.1-MHz band. A separate transceiver isrequired for each baseband or channel use.
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The AN/WSC-5 UHF Transceiver (figure 2-7) isthe common UHF RF satellite terminal installed atNAVCOMTELSTAs for the GAPFILLER subsystem.In FLTSATCOM operations, it is used as the commonRF terminal for all subsystems except the FleetSatellite Broadcast (FSB) and the AntisubmarineWarfare informat ion Exchange Subsys tem(ASWIXS). The AN/WSC-5 can be used to back up theAN/FSC- 79. The AN/WSC-5 transmits in the 248.5-
to 312-MHz range and receives in the 248.5- to270.1-MHz range.
The AN/ARC-143 UHF Transceiver (figure 2-8) isused for ASWIXS communications and is installed atVP Antisubmarine Warfare Operation Centers andaboard P-3C aircraft. The unit has two parts: atransceiver and a radio set control. The AN/ARC-143can be used to transmit or receive voice or data in the255.0- to 399.99-MHz frequency range.
The systems discussed are only a few of theSATCOM equipments used by the Navy. Some of thereferences listed in Appendix III of this module areexcellent sources for more information on satelliteequipment and systems.
FLEET SATELLITECOMMUNICATIONS SYSTEM AND
SUBSYSTEMS
The Flee t Sate l l i te Communica t ions(FLTSATCOM) system and subsystems providecommunications links, via satellite, between shorecommands and mobile units. The system includes RFterminals , subscr iber subsystems, t ra ining,documentation, and logistic support. Within eachsatellite, the RF channels available for use have beendistributed between the Navy and the Air Force.
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Figure 2-5.—AN/SSR-1 receiver system.
Figure 2-6.—AN/FSC-79 Fleet Broadcast Terminal.
Equipments in support of the FLTSATCOMsystem are on ships, submarines, aircraft, and at shorestations. These equipment installations vary in size andcomplexity. Furthermore, with the exception of voicecommunications, the system applies the technology ofprocessor- (computer-) controlled RF links and usesthe assistance of processors in message trafficpreparation and handling.
Although any part of the FLTSATCOM system can
be operated as a separate module, system integration
provides connections for message traffic and voice
communications to DOD communications networks.
A backup capability that can be used in the event of
an outage or equipment failure is provided for both
shore and afloat commands. All subsystems have some
form of backup mode, either from backup equipment
and/or systems, facilities, or RF channels. This
capability is built in as part of the system design and
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Figure 2-7.—AN/WSC-5 UHF Transceiver.
Figure 2-8.—AN/AR5-143 UHF Transceiver.
may limit the ability of selected FLTSATCOM systems
to process information.
FLEET SATELLITE BROADCAST (FSB)SUBSYSTEM
The Fleet Satellite Broadcast (FSB) subsystem is
an expansion of fleet broadcast transmissions that
historically have been the central communications
medium for operating naval units. The FSB transmits
messages, weather information, and intelligence data
to ships. The shore terminal transmits this data on a
direct SHF signal to a satellite, where the signal is
translated to UHF and downlinked. Figure 2-9 shows a
standard FSB subsystem configuration.
COMMON USER DIGITAL INFORMATIONEXCHANGE SYSTEM (CUDIXS) ANDNAVAL MODULAR AUTOMATEDCOMMUNICATIONS SYSTEM (NAVMACS)
The CUDIXS/NAVMACS combine to form acommunications network that is used to transmitgeneral service (GENSER) message traffic betweenships and shore installations. NAVMACS serves asan automated shipboard terminal for interfacingwith CUDIXS (shore-based) and the Fleet Broadcast
System. Figure 2-10 shows a NAVMACS II con-figuration.
OTHER SPECIALIZED SUBSYSTEMS
The FLTSATCOM system represents a compositeof information exchange subsystems that use thesatellites as a relay for communications. The followingsubsystems satisfy the unique communicationrequirements for each of the different navalcommunities.
• Submarine Satellite Information ExchangeSubsystem (SSIXS)
The SSIXS provides a communications systemto exchange message traffic between SSBN andSSN submarines and shore stations.
• Antisubmarine Warfare InformationExchange Subsystem (ASWIXS)
ASWIXS is designed as a communications linkfor antisubmarine warfare (ASW) operationsbetween shore stations and aircraft.
• Tactical Data Information ExchangeSubsystem (TADIXS)
TADIXS is a direct communications linkbetween command centers ashore and afloat.
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Figure 2-9.—Fleet Satellite Broadcast subsystem.
TADIXS provides one-way transmission of datalink communications.
• Secure Voice Subsystem
The secure voice subsystem is a narrowbandUHF link that enables secure voicecommunications between ships. It also allowsconnection with wide-area voice networksashore.
• Tactical Intel l igence (TACINTEL)Subsystem
TACINTEL is specifically designed for specialintelligence communications.
• Control Subsystem
The Control subsystem is a communicationsnetwork that facilitates status reporting andmanagement of FLTSATCOM system assets.
• Officer in Tactical Command InformationExchange Subsystem (OTCIXS)
OTCIXS is designed as a communications linkfor battle group tactical operations.
• Teleprinter Subsystem (ORESTES)
ORESTES is an expansion of the existingteleprinter transmission network.
LEASAT TELEMETRY TRACKING AND
COMMAND SUBSYSTEM
The LEASAT Telemetry Tracking and Commandsubsystem is a joint operation between the U.S. Navyand contractors for controlling LEASATS. Theinstallation of subsystem baseband equipment and RFterminals aboard ships and aircraft is determined bycommunica t ions t ra ffic leve ls , types ofcommunications, and operational missions.
Since Fleet Satellite Broadcast message traffic isa common denominator for naval communications,it is received by numerous types of ships. Insome installations, such as large ships, the fleetbroadcast receiver represents one part of theF LT S AT C O M e q u i p m e n t s u i t e . A t y p i c a lconfiguration on a large ship would include fleetbroadcast, CUDIXS/NAVMACS, secure voice,OTCIXS, TADIXS, teleprinter, and TACINTELequipment.
The FLTSATCOM subsystems apply some formof automated control to the communications beingtransmitted with the exception of the secure voice andcontrol subsystems. This includes message or data linkprocessing before and after transmittal and control ofthe RF network (link control) in which the messagesare being transmitted. The automation of thesefunctions is handled by a processor.
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Figure 2-10.—NAVMACS (V) communications interface.
Much of the message processing beforetransmission and after receipt is fully automatic anddoes not require operator intervention. The actualmessage or data link transmission is fully automatedand under the control of a processor. Within thelimitations of equipment capability, each subsystemaddresses the unique requirements of the user and theenvironment in which the user operates.
DEMAND ASSIGNED MULTIPLE ACCESS(DAMA)
The Demand Assigned Multiple Access (DAMA)was developed to multiplex several subsystems orusers on one satellite channel. This arrangement allowsmore satellite circuits to use each UHF satellitechannel.
Multiplexing
The number of communications networks beingused is constantly increasing. As a result, all areas ofthe RF spect rum have become conges ted .Multiplexing is a method of increasing the number oftransmissions taking place in the radio spectrum perunit of time.
Mul t ip lexing involves the s imul taneoustransmission of a number of intelligible signals usingonly a single transmitting path. As we mentionedearlier, the Navy uses two multiplexing methods:t ime-div is ion mul t ip lex ing (TDM) andfrequency-division multiplexing (FDM). We havealready discussed FDM with the AN/UCC-1.Additional information concerning both methods canbe found in Radio-Frequency CommunicationPrinciples, NEETS, Module 17.
A UHF DAMA subsystem, the TD-1271/UMultiplexer, was developed to provide adequatecapacity for the Navy and other DOD users. Thissubsystem was developed to multiplex (increase) thenumber of subsystems, or users, on 1 25-kHz satellitechannel by a factor of 4.
This factor can be further increased by multiples of4 by patching 2 or more TD-1271’s together. Thismethod increases the number of satellite circuits perchannel on the UHF satellite communications system.Without this system, each satellite communicationssubsystem would require a separate satellite channel.
Transmission Rates
The DAMA equipment accepts encrypted datastreams from independent baseband sources andcombines them into one continuous serial output datastream. DAMA was designed to interface the NavyUHF SATCOM baseband subsystem and theAN/WSC-5 and AN/WSC-3 transceivers.
The TD-1271/U Multiplexer includes a modemintegral to the transceiver. The baseband equipmentinput or output data rate with DAMA equipment can be75, 300, 600, 1,200, 2,400, 4,800, or 16,000 bits persecond (bps). The DAMA transmission rate on thesatellite link (referred to as “burst rate”) can be 2,400,9,600, 19,200, or 32,000 symbols per second.
Circuit Restoral/Coordination
When a termination is lost in either or bothdirections, communications personnel must observespecial guidelines. During marginal or poor periods ofcommunications, the supervisors should assign adedicated operator to the circuit if possible.
When normal circuit restoration procedures areunsuccessfu l and/or a comple te loss ofcommunications exists, an IMMEDIATE precedenceCOMMSPOT message should be transmitted(discussed earlier). Every means available must beused to re-establish the circuit, including messages,support from other ships or NAVCOMTELSTAs, orcoordination via DAMA if available.
The guidelines established in NTP 4, CIBs, andlocal SOPs are not intended to suppress individualinitiative in re-establishing lost communications.Circuit restoral is dependent upon timely action, quickdecisions, and the ability of personnel to use any meansavailable to restore communications in the shortestpossible time.
SPECIAL CIRCUITS
During certain communications operations, youmay be required to activate and operate specialcircuits. Some of the most common special circuits arediscussed next.
UHF AUTOCAT/SATCAT/MIDDLEMAN
RELAY CIRCUITS
Shipboard HERO conditions and emission control(EMCON) restrictions often prohibit transmission ofRF below 30 MHz.
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To provide an uninterrupted flow of essentialcommunications without violating HERO andEMCON restrictions, AUTOCAT, SATCAT, andMIDDLEMAN were developed. With thesetechniques, the range of tactical UHF circuits (voice orteleprinter) can be extended by relay of AM UHFtransmissions via HF or satellite. AUTOCATaccomplishes this using a ship; whereas SATCAT usesan airborne platform for automatically relaying UHFtransmissions. MIDDLEMAN requires an operator tocopy the messages with subsequent manualretransmission.
The three techniques just discussed use threedifferent types of circuit for reception and relay ofUHF transmissions. These circuits are as follows:
• A voice circuit where some units send andreceive on one frequency, and other units sendand receive on any other frequency;
• A voice circuit where all units transmit on onefrequency and receive on another frequency; and
• A RATT circuit where all units transmit on onefrequency and receive on another frequency.
FLEET FLASH NET
The Fleet Flash Net (FFN) is composed of senioroperational staffs and other designated subscribers.The purpose of the FFN is to dis t r ibutehigh-precedence or highly sensitive traffic amongsubscribers. A receipt on the net constitutes firmdelivery, and the message need not be retransmittedover other circuits to receipting stations. The FFN isexplained in more detail in Mission Communications,NTP 11.
ANTENNA SYSTEMS
Operation of communication equipment over theentire range of the RF spectrum requires many types ofatennnas. You will need to know the basic type ofantennas available to you operationally, theircharacteristics, and their uses, Very often, you, theoperator, can mean the difference between efficientand inefficient communications. You will have achoice of many antennas and must select the one mostsuitable for the task at hand. Your operational trainingwill acquaint you with the knowledge necessary toproperly use the antennas at your disposal, However,your operational training WILL NOT acquaint youwith the WHY of antennas, in other words, basicantenna theory. The following topics are intended to
familiarize you with basic antenna terminology,definitions, and characteristics.
ANTENNA CHARACTERISTICS
As you will learn in this section, all antennasexhibit common characteristics. The study of antennasinvolves the following terms with which you mustbecome familiar:
Antenna Reciprocity
The ability of an antenna to both transmit andreceive electromagnetic energy is known as itsreciprocity. Antenna reciprocity is possible becauseantenna characteristics are essentially the same forsending and receiving electromagnetic energy.
Even though an antenna can be used to transmit orreceive, it cannot be used for both functions at the sametime. The antenna must be connected to either atransmitter or a receiver.
Antenna Feed Point
Feed point is the point on an antenna where the RFcable is attached. If the RF transmission line is attachedto the base of an antenna, the antenna is end-fed. If theRF transmission line is connected at the center of anantenna, the antenna is mid-fed or center-fed.
Directivity
The directivity of an antenna refers to the width ofthe radiation beam pattern. A directional antennaconcentrates its radiation in a relatively narrow beam.If the beam is narrow in either the horizontal or verticalplane, the antenna will have a high degree of directivityin that plane. An antenna can be highly directive in oneplane only or in both planes, depending upon its use.
In general, we use three terms to describe the typeof directional qualities associated with an antenna:omnidirectional, bidirectional, and unidirectional.Omnidirectional antennas radiate and receive equallywell in all directions, except off the ends. Bidirectionalantennas radiate or receive efficiently in only twodirections. Unidirectional antennas radiate or receiveefficiently in only one direction.
Most antennas used in naval communications areeither omnidirectional or unidirectional. Bidirectionalantennas are rarely used. Omnidirectional antennas areused to transmit fleet broadcasts and are used aboardship for medium-to-high frequencies. A parabolic, or
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dish, antenna (figure 2-11) is an example of aunidirectional antenna. As you can see in the figure, anantenna (normally a half wave) is placed at the “focal”point and radiates the signal back into a large reflectingsurface (the dish). The effect is to transmit a verynarrow beam of energy tha t i s essent ia l lyunid i rec t ional . F igure 2-12 shows a large ,unidirectional parabolic antenna. Directional antennasare commonly used at shore installations.
Wave Polarization
Polarizat ion of a radio wave is a majorconsideration in the efficient transmission andreception of radio signals. If a single-wire antenna isused to extract energy from a passing radio wave,maximum signal pickup results when the antenna isplaced physically in the same direction as the electric
field component. For this reason, a vertical antenna isused to receive vertically polarized waves, and ahorizontal antenna is used to receive horizontallypolarized waves.
At lower frequencies, wave polarization remainsfairly constant as it travels through space. At higherfrequencies, the polarization usually varies,sometimes quite rapidly. This is because the wave frontsplits into several components, and these componentsfollow different propagation paths.
When antennas are close to the ground, verticallypolarized radio waves yield a stronger signal close tothe Earth than do those that are horizontally polarized.When the transmitting and receiving antennas are atleast one wavelength above the surface, the two typesof polarization are approximately the same in fieldintensity near the surface of the Earth. When thetransmitting antenna is several wavelengths above thesurface, horizontally polarized waves result in astronger signal close to the Earth than is possible withvertical polarization.
Most shipboard communication antennas arevertically polarized. This type of polarization allowsthe antenna configuration to be more easilyaccommodated in the limited space allocated toshipboard communications installations. Verticalantenna installations often make use of the topsidestructure to support the antenna elements. In somecases, to obtain the required impedance match betweenthe antenna base terminal and transmission line, thestructure acts as part of the antenna.
VHF and UHF antennas used for ship-to-aircraftcommunications use both vertical and circularpolarization. Because aircraft maneuvers causecross-polarization effects, circularly polarizedshipboard antennas frequently offer considerablesignal improvements over vertically polarizedantennas.
Circularly polarized antennas are also used forship-to-satellite communications because theseantenntas offer the same improvement as VHF/UHFship-to-aircraft communications operations. Exceptfor the higher altitudes, satellite antenna problems aresimilar to those experienced with aircraft antennaoperations.
Incident Waves
Various factors in the antenna circuit affect theradiation of RF energy. When we energize or feed an
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Figure 2-11.—Principle of parabolic reflection.
Figure 2-12.—Unidirectional parabolic antenna.
antenna with an alternating current (ac) signal, wavesof energy are created along the length of the antenna.These waves, which travel from a transmitter to the endof the antenna, are the incident waves.
Let’s look at figure 2-13. If we feed an ac signal atpoint A, energy waves will travel along the antennauntil they reach the end (point B). Since the B end isfree, an open circuit exists and the waves cannot travelfarther. This is the point of high impedance. Theenergy waves bounce back (reflect) from this point ofhigh impedance and travel toward the feed point,where they are again reflected.
Reflected Waves
We call the energy reflected back to the feed pointthe reflected wave. The resistance of the wiregradually decreases the energy of the waves in thisback-and-forth motion (oscillation). However, eachtime the waves reach the feed point (point A of figure2-13), they are reinforced by enough power to replacethe lost energy. This results in continuous oscillationsof energy along the wire and a high voltage at point Aon the end of the wire. These oscillations are applied tothe antenna at a rate equal to the frequency of the RFvoltage.
In a perfect antenna system, all the energy suppliedto the antenna would be radiated into space. In animperfect system, which we use, some portion of theenergy is reflected back to the source with a resultantdecrease in radiated energy. The more energy reflectedback, the more inefficient the antenna. The conditionof most antennas can be determined by measuring thepower being supplied to the antenna (forward power)and the power being reflected back to the source(reflected power). These two measurements determinethe voltage standing wave ratio (VSWR), whichindicates antenna performance.
If an antenna is resonant to the frequency suppliedby the transmitter, the reflected waves and the incidentwaves are in phase along the length of the antenna andtend to reinforce each other. It is at this point that
radiation is maximum, and the SWR is best. When theantenna is not resonant at the frequency supplied by thetransmitter, the incident and reflected waves are out ofphase along the length of the antenna and tend to cancelout each other. These cancellations are called powerlosses and occur when the SWR is poor, such as 6:1 or5:1.
Most transmitters have a long productive life andrequire only periodic adjustment and routinemaintenance to provide maximum operating efficiencyand reliable communications. Experience has shownthat many of the problems associated with unreliableradio communication and transmitter failures can beattributed to high antenna VSWR.
Dummy Loads
Under radio silence conditions, placing a carrieron the air during transmitter tuning would give anenemy the opportunity to take direction-findingbearings and determine the location of the ship. Evenduring normal periods of operation, transmittersshould be tuned by methods that do not requireradiation from the antenna. This precaution minimizesinterference with other stations using the circuit.
A dummy load (also called dummy antenna) canbe used to tune a transmitter without causing unwantedradiation. Dummy loads have resistors that dissipatethe RF energy in the form of heat and prevent radiationby the transmitter during the tuning operation. Thedummy load, instead of the antenna, is conected to theoutput of the transmitter, and the normal transmittertuning procedure is followed.
Most Navy transmitters have a built-in dummyload. This permits you to switch between the dummyload or the actual antenna, using a switch. Fortransmitters that do not have such a switch, thetransmission line at the transmitter is disconnected andconnected to the dummy load (figure 2-14). Whentransmitter tuning is complete, the dummy load isdisconnected and the antenna transmission line isagain connected to the transmitter.
ELECTROMAGNETIC WAVELENGTH
Electromagnetic waves travel through free space at186,000 miles per second. But, because of resistance,the travel rate of these waves along a wire is slightlyslower. An antenna must be an appropriate length sothat a wave will travel from one end to the other andreturn to complete one cycle of the RF voltage. Awavelength is the distance traveled by a radio wave in
2-14
Figure 2-13.—Incident and reflected waves on an antenna.
one cycle. This means that wavelength will vary withfrequency.
If we increase the frequency, the time required tocomplete one cycle of alternating current (ac) isnaturally less; therefore, the wavelength is less. If wedecrease the frequency, the time required to completeone cycle of ac is longer; therefore, the wavelength islonger. Another word used to represent wavelength isLAMBDA (designated by the symbol λ).
The term “wavelength” also refers to the length ofan antenna. Antennas are often referred to as halfwave, quarter wave, or full wave. These termsdescribe the relative length of an antenna, whether thatlength is electrical or physical. Figure 2-15 shows atheoretical half-wave antenna with a center feed point.Both sections of the antenna relative length of anantenna, whether that length is electrical or physical.
Earlier, we said that when tuning an antenna, weare electrically lengthening or shortening the antennato achieve resonance at that frequency. We are actuallychanging the wavelength of the antenna. The electricallength of an antenna may not be the same as its physicallength.
You know that RF energy travels through space atthe speed of light. However, because of resistance, RFenergy on an antenna travels at slightly less than the
speed of light. Because of this difference in velocity,the physical length no longer corresponds to theelectrical length of an antenna. Therefore, an antennamay be a half-wave antenna electrically, but it isphysically somewhat shorter. For information on howto compute wavelengths for different frequencies,consult NEETS, Module 12, Modulation Principles.
BASIC ANTENNAS
Many types and variations of antenna design areused in the fleet to achieve a particular directiveradiation pattern or a certain vertical radiation angle.However, all antennas are derived from two basictypes: the half wave and the quarter wave.
HALF-WAVE ANTENNA
An antenna that is one-half wavelength long is theshortest antenna that can be used to radiate radiosignals into free space. The most widely used antennais the half-wave antenna, commonly called a dipole, orhertz, antenna. This antenna consists of two lengths ofwire rod, or tubing, each one-fourth wavelength long ata certain frequency.
Many complex antennas are constructed from thisbasic antenna design. This type of antenna will notfunction efficiently unless its length is one-halfwavelength of the frequency radiated or received.
Figure 2-15 shows a theoretical half-wave antennawith a center feed point. Both sections of the antennaare λ/4 (one-fourth wavelength) at the operatingfrequency. Together, of course, the sections make theeffective length of the antenna λ/2 (one-halfwavelength) at the operating frequency.
One feature of the dipole antenna is that it does notneed to be connected to the ground like other antennas.Antennas shorter than a half wavelength must use theground to achieve half-wave characteristics. Thehalf-wave antenna is already long enough to radiate thesignal properly.
Because of sophisticated antenna systems andtuning processes, half-wave antennas can beelectrically achieved aboard ship. Thereforewavelength is becoming less and less the criteria fordetermining the types of antennas to be used on ships.Dipole antennas can be mounted horizontally orvertically, depending upon the desired polarization,and can be fed at the center or at the ends. Because it isungrounded, the dipole antenna can be installed aboveenergy-absorbing structures.
2-15
Figure 2-14.—DA-91/U dummy load.
Figure 2-15.—Half-wave antenna with center feed point.
QUARTER-WAVE ANTENNA
A quarter-wave antenna is a grounded antenna thatis one-fourth wavelength of the transmitted or receivedfrequency. You will hear the quarter-wave antennareferred to as a “Marconi antenna.” The quarter-waveantenna is also omnidirectional.
As we mentioned earlier, a half-wave antenna isthe shortest practical length that can be effectively usedto radiate radio signals into free space. The naturalquestion, then is, “How do we use a quarter-wavelength antenna if a half-wavelength is the shortestlength that can be used?” The answer is simple.
Two components make up the total radiation froman antenna. One component is the part of the radiatedsignal that leaves the antenna directly. The other is aground reflection that appears to come from anunderground image of the real antenna (figure 2-16).This image is sometimes called the mirror image andis considered to be as far below the ground as the realantenna is above it.
Figure 2-17 shows basic current distribution in areal and image antenna. There are certain directions inwhich the direct wave from the real antenna and thereflected wave from the image are exactly equal inamplitude but opposite in phase. Conversely, there areother directions in which the direct and reflected wavesare equal in amplitude and in phase. Therefore,
depending on the direction and location of the point atwhich the field strength is measured, the actual fieldstrength may be (1) twice the field strength from thereal antenna alone, (2) zero field strength, or (3) someintermediate value between maximum and minimum.It is this “real” and “image” radiated field that formsthe basis for using quarter-wavelength antennas.
This reflected-energy principle is very useful inthe lower frequency ranges, although groundreflections occur in the high-frequency range as well.
The antenna does not always need to be placed atthe Earth’s surface to produce an image. Anothermethod of achieving reflected images is through theuse of ground planes. This means that a large reflectingmetallic surface is used as a substitute for the ground orEarth. This method is frequently used in the VHF/UHFfrequency ranges. Figure 2-18 shows a commonlyused UHF antenna (AS-390/SRC), which uses thisprinciple. The ground plane is sometimes referred to asa “counterpoise,” as shown in the figure. Together, thecounterpoise and the radials form the reflectingsurface, which provides the reflected image.
TYPES OF SHIPBOARD ANTENNAS
Figure 2-19 shows various shipboard antennas andtheir placements. The complex structures of modernships and their operational requirements require theuse of many types of antenna. These types include wirerope fans, whips, cages, dipoles, probes, trussedmonopoles, and bow stubs. The selection and use ofdifferent types is often governed by the limited spaceavailable.
2-16
Figure 2-16.—Direct and image signal of a quarter-waveantenna.
Figure 2-17.—Current distribution in a real antennaand its image.
Figure 2-18.—AS-390/SRC UHF antenna withcounterpoise, or ground plane.
WIRE ROPE ANTENNAS
Wire rope antennas are installed aboard ship formedium- and high-frequency (300 kHz to 30 MHz)coverage. A wire rope antenna (figure 2-20) consists ofone or more lengths of flexible wire rigged from two ormore points on the ship’s supurstructure. A wire ropeantenna is strung either vertically or horizontally froma yardarm or mast to outriggers, another mast, or to thesuperstructure. If used for transmitting, the wireantenna is tuned electrically to the desired frequency.
Receiving wire antennas are normally installedforward on the ship, rising nearly vertically from the
pilothouse top to brackets on the mast or yardarm.Receiving antennas are located as far as possible fromthe transmitting antennas so that a minimum of energyis picked up from local transmitters.
Because of the characteristics of the frequencyrange in which wire antennas are used, the ship’ssuperstructure and other nearby structures become anelectronically integral part of the antenna. As a result,wire rope antennas are usually designed or adaptedspecifically for a particular ship.
WHIP ANTENNAS
Whip antennas are used for medium- andhigh-frequency transmitting and receiving systems.For low-frequency systems, whip antennas are usedonly for receiving. Essentially self-supporting, whipantennas may be deck-mounted or mounted onbrackets on the stacks or superstructure. Theself-supporting feature of the whip makes itparticularly useful where space is limited and inlocations not suitable for other types of antennas. Whipantennas can be tilted, a design feature that makes themsuited for use along the edges of aircraft carrier flightdecks. Aboard submarines, they can be retracted intothe sail structure.
Whip antennas commonly used aboard ship are 25,28, or 35 feet long and consist of several sections. The35-foot whip is most commonly used. If these antennasare mounted less than 25 feet apart, they are usuallyconnected with a crossbar with the feed point at itscenter. The twin whip antenna (figure 2-21) is notbroadband and is generally equipped with a basetuning unit.
2-17
Figure 2-19.—Shipboard antenna systems.
Figure 2-20.—Wire rope fan antenna.
VHF AND UHF ANTENNAS
The physical size of VHF and UHF antennas isrelatively small because of the short wavelengths atthese frequencies. Aboard ship, these antennas areinstalled as high and as much in the clear aspossible .Since VHF and UHF antennas areline-of-sight systems, they require a clear area at anoptimum height on the ship structure or mast.Unfortunately, this area is also needed for various
radars and UHF direction-finding and navigational aid
systems.
VHF and UHF antennas are usually installed on
stub masts above the foremast and below the UHF
direction finder. UHF antennas are often located on the
outboard ends of the yardarms and on other structures
that offer a clear area.
For best results in the VHF and UHF ranges, both
transmitting and receiving antennas must have the
same polarization. Vertically polarized antennas are
used for all ship-to-ship, ship-to-shore, and
ground-to-air VHF/UHF communications. Usually,
either a vertical half-wave dipole or a vertical
quarter-wave antenna with ground plane is used. An
example of a UHF half-wave (dipole) antenna is the
AT-150/SRC, shown in figure 2-22. This antenna is
normally mounted horizontally.
BROADBAND ANTENNAS
Broadband antennas for HF and UHF bands have
been developed for use with antenna multicouplers.
Therefore, several circuits may be operated with a
single antenna. Broadband antennas must be able to
transmit or receive over a wide frequency band.
HF broadband antennas include the 35-foot twin
and trussed whips, half-cone, cage, and a variety of
fan-designed antennas. The AT-150/SRC UHF
antenna in figure 2-22 is an example of a broadband
antenna.
2-18
Figure 2-21.—Twin whip antenna with crowbar.
Figure 2-22.—AT-150/SRC UHF antenna.
SATCOM ANTENNAS
The antennas shown in figures 2-23 and 2-24 areused for sa te l l i te communica t ions . The0E-82C/WSC-1(V) antenna (figure 2-23) is used withthe AN/WSC-3 transceiver (figure 2-25) and designedprimarily for shipboard installation. Depending uponrequirements, one or two antennas may be installed toprovide a view of the satellite at all times. The antennais attached to a pedestal. This permits the antenna torotate so that it is always in view of the satellite. Thefrequency band for receiving is 248 to 272 MHz and fortransmitting is 292 to 312 MHz.
The AN/SRR-1 receiver system consists of up tofour AS-2815/SSR-1 antennas (figure 2-24) with anamplifier-converter AM-6534/SSR-1 for eachantenna. The antennas are used to receive satellite fleetbroadcasts at frequencies of 240 to 315 MHz. Theantenna and converters are mounted above deck so thatat least one antenna is always in view of the satellite.
2-19
Figure 2-23.—OE-82C/WSC-1(V) antenna group.
Figure 2-24.—AS-2815/SSR-1 antenna physicalconfiguration.
The newer satellite systems use the SHF band. Oneof the major advantages of these systems is that theyuse a very small parabolic antenna measuring only 12inches in diameter.
A satellite antenna must be pointed at the satelliteto communicate. We must first determine the azimuth(AZ) and elevation (EL) angles from a fixed location.Figure 2-26 illustrates how these angles are derived,
using a pointing guide called the Equatorial SatelliteAntenna Pointing Guide. This guide is normallyavailable through the Navy Supply System.
The antenna pointing guide is a clear plasticoverlay, which slides across a stationary map. Itindicates AZ and EL angles in degrees to the satellite.The values obtained are useful to the operator in settingup the antenna control unit of a satellite system.
2-20
Figure 2-25.—AN/WSSC-3 UHF transceiver.
Figure 2-26.—Equatorial Satellite Antenna Pointing Guide.
To use the guide, follow these procedures:
• Center the overlay directly over the desiredsatellite position on the stationary map.
• Mark the latitude and longitude of the ship on theplastic antenna pointing guide with a greasepencil.
• Determine the approximate azimuth angle fromthe ship to the satellite.
• Locate the closest dotted line radiating outwardfrom the center of the graph on the overlay inrelation to the grease dot representing the ship’slocation. This dotted line represents degrees ofazimuth as printed on the end of the line. Someapproximation will be required for shippositions not falling on the dotted line.
• Determine the degrees of elevation by locatingthe solid concentric line closest to the ship’smarked position. Again, approximation will berequired for positions not falling directly on thesolid elevation line. Degrees of elevation aremarked on each concentric line.
Example: Assume that your ship is located at 30°north and 70° west. You want to access FLTSAT 8 at23° west. When we apply the procedures above, we candetermine an azimuth value of 115° and an elevationangle of 30°.
TYPES OF SHOREBASED ANTENNAS
There is a variety of shorebased antennas just asshipbased antennas. In the following paragraphs wewill acquaint you with some of the shorebased.
RHOMBIC ANTENNA
The rhombic antenna, usually used at receiversites, is a unidirectional antenna. This antenna consistsof four long wires, positioned in a diamond shape.Horizontal rhombic antennas are the most commonlyused antennas for poin t - to-poin t HF navalcommunications. The main disadvantage of thisantenna is that it requires a relatively large area.
MULTIWIRE RHOMBIC
A rhombic antenna improves in performance ifeach leg is made up of more than one wire. An
improved antenna, known as a curtain rhombic, usesthree wires spaced 5 to 7 feet apart for each leg andconnected to a common point (figure 2-27).
SLEEVE ANTENNA
The sleeve antenna is used primarily as a receivingantenna. It is a broadband, vertically polarized,omnidirectional antenna. Its primary uses are inbroadcast , ship- to-shore, and ground-to-aircommunications. Although originally developed forshore stations, there is a modified version forshipboard use. Figure 2-28 shows a sleeve antenna forshore stations.
Sleeve antennas are especially helpful in reducingthe total number of conventional narrowband antennasthat otherwise would be required to meet therequirements of shore stations. With the use ofmulticouplers, one sleeve antenna can serve severalreceivers operating over a wide range of frequencies.This feature also makes the sleeve antenna ideal forsmall antenna sites.
CONICAL MONOPOLE ANTENNA
The conical monopole antenna (figure 2-29) isused in HF communications. It is a broadband,vertically polarized, compact omnidirectionalantenna. This antenna is adaptable to ship-to-shore,broadcast, and ground-to-air communications. It isused both ashore and aboard ship.
When operating at frequencies near the lower limitof the HF band, the conical radiates in much the samemanner as a regular vertical antenna. At the higherfrequencies, the lower cone section radiates, and thetop section pushes the signal out at a low angle as a skywave. This low angle of radiation causes the sky waveto return to the Earth at great distances from theantenna. Therefore, this antenna is well suited forlong-distance communications in the HF band.
2-21
ITf02030
Figure 2-27.—Three-wire rhombic antenna.
INVERTED CONE ANTENNA
The inverted cone antenna (figure 2-30) isvertically polarized, omnidirectional, and verybroadbanded. It is used for HF communications inship- to-shore, broadcast , and ground-to-airapplications. The radial ground plane that forms theground system for inverted cones is typical of therequirement for vertically polarized, ground-mountedantennas. The radial wires are one-quarter-wavelengthlong at the lowest designed frequency.
LOG-PERIODIC ANTENNA
The log-periodic (LP) antenna operates over anextremely-wide frequency range in the HF and VHFbands. Figure 2-31 shows a typical LP antennades igned for ext remely broadbanded, VHFcommunications. The LP antenna can be mounted onsteel towers or utility poles that incorporate rotating
mechanisms. This antenna is particularly useful whereantenna area is limited. A rotatable LP antenna, knownas an RLP antenna (figure 2-32), possesses essentiallythe same characteristics as the fixed LP antenna but hasa different physical form. The RLP antenna iscommonly used in ship-shore-sh ip and inpoint-to-point communications.
EMERGENCY ANTENNAS
Damage to an antenna from heavy seas, violentwinds, or enemy action can cause serious disruption ofcommunications. Sections of a whip antenna can becarried away, insulators can be damaged, or a wire
2-22
RMf02032
Figure 2-29.—Conical monopole antenna.
INSULATORS
RADIALGROUND PLANE
SUPPORTING POLES
WIRE ELEMENTS OFINVERTED CONE
FEEDPOINT
ITf02033
Figure 2-30.—Inverted cone antenna.
TRUCK FEEDLINE
TOTRANSMISSION
LINE
SLEEVESECTION
RADIATINGSECTION
RMf02031
Figure 2-28.—Sleeve antenna (shore stations).
antenna can snap loose from its moorings or break. Ifloss or damage should happen when all availableequipment is needed, you may have to rig, or assist inrigging an emergency antenna to temporarily restorecommunications until the regular antenna can berepaired.
The simplest emergency antenna consists of alength of wire rope to which a high-voltage insulator is
attached to one end and a heavy alligator clip, or lug, issoldered to the other. The end with the insulator ishoisted to the nearest structure and secured. The endwith the alligator clip (or lug) is attached to theequipment transmission line. To radiate effectively, theantenna must be sufficiently clear of all groundedobjects.
ANTENNA DISTRIBUTION SYSTEMS
In figure 2-33, we see a distribution system withone antenna that can be connected (patched) to one ofseveral receivers or transmitters by way of amulticoupler. In this system, you can patch the antennato only one receiver or transmitter at a time. However,some distribution systems are more complex, such asthe one shown in figure 2-34. In this system, you canpatch four antennas to four receivers, or you can patchone antenna to more than one receiver via themulticoupler. In either system, we need a way toconnect the antenna to the receiver or transmitter thatwe want to use.
Figure 2-35 shows a receiver antenna filter patchpanel, AN/SRA-12, with a receiver patch panel. TheAN/SRA-12 provides seven radio-frequency channelsin the 14-kHz to 32-MHz range. Any or all of thesechannels can be used independently of any otherchannel, or they can operate simultaneously.
2-23
RADIATOR
ALUMINUMBOOM ROTATE
GUY
TRIANGULARSTEELTOWER
BALUNTRANSFORMER ITf02035
Figure 2-32.—Rotatable log-periodic antenna.
ITf02034
Figure 2-31.—Log-periodic antenna.
On the receiver patch panel, a receiver is hardwiredto each jack. With the use of patchcords, you canconnect a receiver, tuned to a particular frequency, tothe antenna by connecting the receiver to the properjack on the AN/SRA-12. Figure 2-35 shows how thefilter assembly is used in combination with other units
to pass an RF signal from an antenna to one or morereceivers.
Transmitting antenna distribution systemsperform the same functions as receiving distributionsystems.
ANTENNA POSITIONING
The raising and lowering of antennas is associatedwith flight quarter refueling or PMS operations.Extreme care should be taken that all moving parts arein correct operating conditions; also the Officer of theDeck and Communications Watch Officer must beinformed before physical movement of the antennas.
USE DIRECTIONAL ANTENNAS
Reception is defined as when an electromagneticwave passes through a receiver antenna and induces avoltage in that antenna. Further detailed informationon antennas, antenna use, wave propagation and wavegeneration can be found in NEETS MODULES 9, 10,and 17.
Rotate For Optimum Reception
Rotating for optimum reception is accomplishedby both physical and mechanical means of moving theantenna(s) to properly align and tune the antenna.
2-24
UHF ANTENNA
CH-1
CH-2
CH-4
CH-3
RF
RF
RF
RF
TRANSMITTER
AND/OR
RECEIVER NO. 1
TRANSMITTER
AND/OR
RECEIVER NO. 2
TRANSMITTER
AND/OR
RECEIVER NO. 3
TRANSMITTER
AND/OR
RECEIVER NO. 4
MULTI-COUPLER
ITf02036
Figure 2-33.—Antenna multicoupler interconnection diagram.
RCV RCV RCV RCV
RECEIVING ANTENNAPATCH PANEL
FILTER ASSEMBLY
ANTENNA COUPLERGROUP
RECEIVER RFPATCH PANEL
TUNERCONTROL
RCVR1
RCVR2
RCVR3
RCVR4
RECEIVER TRANSFER SWITCHBOARD(AUDIO)
ITf02037
Figure 2-34.—Complex distribution system.
Align For Optimum Reception
Using the correct antenna location (by rotation)and the correct equipment for the system, you willbring the antenna into alignment and be ready for thefinal step, which is tuning.
ANTENNA COUPLING
Antenna couplers (fig. 2-36) are used to commentone antenna to a transmitter or receiver and“electronically tunes” the signal to the antenna. Anantenna multicpupler (fig. 2-37) connects one antennato several transmitters or receivers and permitssimultaneous operation of transmitter. An antennafilter connects one or more HF receivers to a singleantenna.
Tune For Optimum Reception
There are two objectives of antenna tuning: (1) totune out the various impedances and (2) to match thelength of the antenna to the frequency radiated at itscharacteristic impedance.
• Impedance: everything exhibi ts someimpedance. Even a straight piece of copper wire3 inches long will offer some resistance tocurrent flow, however small. The characteristicimpedance of this same piece of copper wire isits overall resistance to a signal.
The transmission line between an antenna and atransmitter has a certain amount of characteristicimpedance. The antenna also has a certain
2-25
ITf02038
Figure 2-35.—AN/SRA-12 antenna filter patch panel with receiver antenna patch panel.
Figure 2-36.—SRA-56, 57, 58 antenna coupler.
amount of characteristic impedance. This basicmismatch in impedance between the transmitterand the antenna makes antenna tuning necessary.Naturally, as transmitters, transmission lines,and antennas become more complex, antennatuning becomes more critical.
• Antenna tuning: Transmit antenna turning is theelectrical shortening or lengthening of theantenna to a desired frequency. Electricalchanging of an antenna’s length does notphysically change the length of the antenna. Acoupler performs the tuning process. When theantenna is tuned to the desired operatingfrequency, it is said to be “RESONANT.”Receive antenna tuning uses band pass filteringto pass the frequency selected to the receiver.
You will find that the better the ability of thereceiver to reject unwanted signals, the better itsselectivity, The degree of selection isdeterminedly the sharpness of resonance towhich the frequency-determining circuits havebeen engineered and tuned. You usually measureselectivity by taking a series of sensitivityreadings. As you take the readings, you step theinput signal along a band of frequencies aboveand below the circuit resonance of the receiver;for example, 100 kilohertz below to 100kilohertz above the tuned frequency. As you
approach the tuned frequency, the input levelrequired to maintain a given output level will fall.As you pass the tuned frequency, the requiredinput level will rise. Input voltage levels are thencompared with frequency. They can be plotted onpaper, or you can view them on an oscilloscope.They appear in the form of a response curve. Thesteepness of the response curve at the tunedfrequency indicates the selectivity of thereceiver, thus allowing for the optimumreception.
RF SAFETY PRECAUTIONS
Although electromagnetic radiation fromtransmission lines and antennas is usually ofinsufficient strength to electrocute personnel, it canlead to other accidents and compound injuries.Voltages may be inducted in ungrounded metalobjects, such as wire guys, wire cable (hawser), handrails, or ladders, If you should come in contact withthese objects, you could receive a shock or RF burn.This shock can cause you to jump or fall into nearbymechanical equipment or, when working aloft, to fallfrom an elevated work area. Take care to ensure that alltransmission lines or antennas are deenergized beforeworking near or on them.
Guys, cables, rails and ladders should be checkedfor RF shock dangers. Working aloft “chits” and safetyharnesses should be used for your safety. Signing a“working aloft chit” signifies that all equipment is in anonradiating status (the equipment is not moving). Theperson who signs the chit should ensure that no RFdanger exists in areas where personnel are working.
Nearby ships or parked aircraft are another sourceof RF energy that must be considered when checkingwork areas for safety. Combustible materials can beignited and cause severe fires from arcs or heatgenerated by RF energy. RF radiation can detonateordnance devices by inducing currents in the internalwiring of the device or in the external test equipment,or leads connected to the device.
You should always obey RF radiation warningsigns and keep a safe distance from radiating antennas.The six types of warning signs for RF radiation hazardare shown in figure 2-38.
RF BURNS
Close or direct contact with RF transmission linesor antennas may result in RF burns. These are usually
2-26
Figure 2-37.—OA-9123 antenna multicoupler.
deep, penetrating, third-degree burns. To healproperly, these burns must heal from the inside to theskin surface. To prevent infection, you must giveproper medical attention to all RF burns, including thesmall “pinhole” burns. Petrolatum gauze can be used tocover burns temporarily before the injured personreports to medical facilities for further treatment.
DIELECTRIC HEATING
Dielectric heating is the heating of an insulatingmaterial by placing it in a high-frequency electric field.The heat results from internal losses during the rapidreversal of polarization of molecules in the dielectricmaterial.
In the case of a person in an RF field, the body actsas a dielectric, If the power in the RF field exceeds 10milliwatts per centimeter, a person in that field willhave noticeable rise in body temperature. The eyes arehighly susceptible to dielectric heating. For thisreason, you should not look directly into devices
radiating RF energy. The vital organs of the body arealso susceptible to dielectric heating. For your ownsafety, you must not stand directly in the path of RFradiating devices.
PRECAUTIONS WHEN WORKING ALOFT
Before going aloft, you must follow all NAVOSHand local requirements such as wearing a harness and ahard hat. You must have a safety observer and meet allother requirements.
When radio or radar antennas are energized bytransmitters, you must not go aloft unless advance testsshow that little or no danger exists. A casualty canoccur from even a small spark drawn from a chargedpiece of metal or rigging. Although the spark itself maybe harmless, the “surprise” may cause you to let go ofthe antenna involuntarily, and you may fall. There isalso a shock hazard if nearby antennas are energized.
Rotating antennas also may cause you to fall whenyou are working aloft. Motor safety switches
2-27
ITf02041
Figure 2-38.—Examples of RF radiation warning signs.
controlling the motion of rotating antennas must betagged and locked opened before you go aloft nearsuch antennas.
When working near a stack, you should draw andwear the recommended oxygen breathing apparatus.Among other toxic substances, stack gas containscarbon monoxide. Carbon monoxide is too unstable tobuild up to a high concentration in the open, butprolonged exposure to even small quantities isdangerous.
SUMMARY
Naval communications using satellite and variousantennas types must always be ready to shift from
peacetime to wartime requirements. To this end, thediversity of fleet communication operations has giventhe Navy an expanded capabi l i ty to meetever-increasing command, control, and supportrequirements by use of satellites and assortedantennas.
Additionally, this variety of communicationstechnology has increased the requirements for greaterproficiency from all operating personnel. As an IT, youwill be tasked with higher levels of performance in anincreasingly technical Navy.
2-28
APPENDIX I
GLOSSARY
A
ANTENNA—A device used to radiate or receiveradio waves.
ANTENNA COUPLER—A device used forimpedance matching (tuning) between anantenna and a transmitter or receiver.
ANTENNA RECIPROCITY—The ability of anantenna to both transmit and receiveelectromagnetic energy.
ANTENNA TUNING—The process where anantenna is electrically “matched” to theoutput frequency and impedance of thetransmitter.
ATTENUATION—A deliberate reduction or anunintended loss in RF signal strength.
B
BANDWIDTH—Any section of the frequencyspectrum occupied by specific signals.
BIDIRECTIONAL ANTENNA—An antenna thatradiates in or receives most of its energy fromonly two directions.
BLACK—Cipher text or encrypted text orinformation.
C
CARRIER—The unmodulated signal originallyproduced in the oscillator section of atransmitter.
CARRIER FREQUENCY—The final RF outputwithout modulation. The assigned transmitterfrequency.
CHANNEL—A carrier frequency assignment,usually with a fixed bandwidth.
COMPLEX WAVE—A transmitted radio signalcomposed of different frequencies.
COUNTERPOISE—The ground plane, or reflectivesurface, comprising an antenna’s reflectedimage at a given wavelength.
CRITICAL FREQUENCY—The highesttransmitted frequency that can be propagated
directly upward and still be bent, or“refracted,” back to Earth.
CYCLE—Two complete alternations of alternatingcurrent, or one complete revolution in anyperiod of time, equal to 360°.
D
DAMA— (DEMAND ASSIGNED MULTIPLEACCESS SUBSYSTEM)—Subsystem thatmultiplexes several subsystems on onesatellite channel.
DIFFRACTION—The bending of radio wavesaround the edges of a solid objector densemass.
DIRECTIONAL ANTENNA—An antenna thatradiates or receives radio waves moreeffectively in some directions than in others.
DIRECTIVITY—The sharpness or narrowness of anantenna’s radiation pattern in a given plan.
DIRECT WAVE—A radio signal that travels in adirect line-of-sight path from the transmittingantenna to the receiving antenna.
DUMMY LOAD—A nonradiating device used at theend of a transmission line in place of anantenna for tuning a transmitter, The dummyload converts transmitted energy into heat sothat no energy is radiated outward or reflectedback.
E
EHF (EXTREMELY-HIGH FREQUENCY)—Theband of frequencies from 30 GHz to 300GHz.
ELECTRIC FIELD—A field produced as a result ofa voltage charge on an antenna.
ELECTROMAGNETIC ENERGY—An RF sourcecomposed of both an electric and a magneticfield.
ELECTROMAGNETIC WAVES—Energyproduced at the output of a transmitter; alsocalled radio waves.
AI-1
F
FADING—Variation, usually gradual, in the fieldstrength of a radio signal that is caused bychanges in the transmission path or medium.
FEED POINT—The point on an antenna at whichthe RF cable that carries the signal from thetransmitter is connected.
FOT (FREQUENCY OF OPTIMUMTRANSMISSION)—The most reliablefrequency for propagation at a specific time.
FREQUENCY—The number of complete cycles perunit of time.
FREQUENCY DIVERSITY—The method in whichthe information signal is transmitted andreceived on two separate radio frequenciessimultaneously to take advantage of the factthat fading does not occur simultaneously ondifferent frequencies.
FSK (FREQUENCY-SHIFT KEYING)—The processof shifting the incident carrier above andbelow the carrier frequency to correspond tothe marks and spaces of a teleprinter signal.
G
GAIN—An increase in signal strength.
GIGAHERTZ (GHz)—A unit of frequency equal to1000 megahertz.
GROUND—A term used to denote a commonelectrical point of zero potential.
GROUND-PLANE ANTENNA—A type of antennathat uses a ground plane (a metallic surface)as a simulated ground to produce low-angleradiation.
H
HALF-WAVE DIPOLE ANTENNA—A commontype of half-wave antenna made from astraight piece of wire cut in half. Each halfoperates at a quarter of the wavelength. It isnormally omnidirectional with no gain.
HERTZ (Hz)—A unit of frequency equal to onecycle per second.
HERTZ ANTENNA—An ungrounded half-waveantenna that is installed some distance aboveground and positioned either vertically orhorizontally.
HF (HIGH FREQUENCY)—The band of frequenciesfrom 3MHz to 30MHz.
I
IMPEDANCE—The total opposition to the flow ofalternating current.
INCIDENT WAVE—The RF energy that travels fromthe transmitter to the antenna for radiation.
INDUCTION FIELD—The electromagnetic fieldproduced around an antenna when current andvoltage are present on the antenna.
K
KILOHERTZ (kHz)—A unit of frequency equal to1000 hertz.
L
LEASAT—Leased satellite.
LF (LOW FREQUENCY)—The band of frequenciesfrom 30kHz to 300kHz.
LUF (LOWEST USABLE FREQUENCY)—Thelowest frequency that can be used at a specifictime for ionospheric propagation of radiowaves between two specified points.
M
MAGNETIC FIELD—One of the fields producedwhen current flows through a conductor or anantenna.
MARCONI ANTENNA—A quarter-wave antennathat is operated with one end grounded; it ispositioned perpendicular to the Earth.
MEGAHERTZ (MHz)—A unit of frequency equal tol,000,000 hertz.
MF (MEDIUM FREQUENCY)—The band offrequencies from 300kHz to 3MHz.
MIRROR IMAGE—The part of the radiated signalof a quarter-wave antenna (Marconi antenna)appearing to come from an undergroundimage of the real antenna. This image is alsocalled ground reflection.
MODULATED WAVE—The wave that results afterthe information from the modulating signal isimpressed onto the carrier signal. The wavethat is transmitted.
MODULATION—The process of adding, orsuperimposing, information on an RF carrierwave.
AI-2
MUF (MAXIMUM USABLE FREQUENCY)—Thehighest operating frequency that can be usedat a specific time for successful radiocommunications between two points.
O
OMNIDIRECTlONAL ANTENNA—An antennathat radiates or receives equally well in alldirections, except directly off the ends.
OSCILLATOR—An electrical circuit that generatesalternating current at a particular frequency.
P
PARABOLIC ANTENNA—An antenna that radiatesits signal back into a large reflecting surface(called the dish) for radiation.
PERIOD (of a wave)—The time required to completeone cycle of a waveform.
POLARIZATION (of antennas)—The plane(horizontal or vertical) of the electric field asradiated from a transmitting antenna.
R
RADHAZ (RADIATIONHAZARD)—Electromagnetic radiationhazard generated from electronic equipment.
RADIATION FIELD—The electromagnetic fieldthat radiates from an antenna and travelsthrough space.
RADIATION RESISTANCE—The resistance that,if inserted in place of an antenna, wouldconsume the same amount of power that isradiated by the antenna.
RECIPROCITY—See antenna reciprocity.
RED—Plain text or unencrypted information.
REFLECTED WAVE—An electromagnetic wavethat travels back toward the transmitter fromthe antenna because of a mismatch inimpedance between the two.
REFLECTION—Occurs when a radio wave strikesthe Earth’s surface at some distance from thetransmitting antenna and is returned upwardtoward the atmosphere.
RF (RADIO FREQUENCY)—A frequency in therange within which radio waves can betransmitted. Frequencies used for radiocommunication fall between 3kHz and300GHz.
RF ENERGY—Radio frequency energy. Energyproduced at the output of a transmitter.
S
SATELLITE COMMUNICATION (SATCOM)—Atype of worldwide, reliable, high-capacity,secure, and cost-effective telecommunicationssystem using satellites.
SHF (SUPER-HIGH FREQUENCY)—The band offrequencies from 3 GHz to 30 GHz.
SIGNAL—Detectable transmitted energy that can beused to carry information.
SWITCHBOARD—Device that connects receiveroutputs to numerous pieces of equipment.
T
TRANSMISSION LINE—A device designed toguide electrical or electromagnetic energyfrom one point to another.
U
UHF (ULTRA HIGH FREQUENCY)—The band offrequencies from 300 MHz to 3 GHz.
UNIDIRECTIONAL ANTENNA—An antenna thatradiates in only one direction.
V
VHF (VERY-HIGH FREQUENCY)—The band offrequencies from 30 MHz to 300 MHz.
VLF (VERY-LOW FREQUENCY)—The band offrequencies from 3 kHz to 30 kHz.
W
WAVEFORM—The shape of an electromagneticwave.
WAVELENGTH—The distance traveled, in feet ormeters, by a radio wave in the time requiredfor one cycle.
AI-3
APPENDIX II
GLOSSARY OF ACRONYMSAND ABBREVIATIONS
A
ASWIXS—Antisubmarine Warfare InformationExchange Subsystem.
ASWOC—Antisubmarine Warfare OperationsCenter.
AZ—Azimuth.
C
CAT—Communications assistance team.
CONUS—Continental United States.
CUDIXS—Common User Digital InformationExchange System.
CW—Continuous wave (Morse code).
D
DAMA—Demand Assigned Multiple AccessSubsystem.
dc—Direct current.
DSB—Double-side band.
DSCS—Defense Satellite Communications System.
E
EHF—Extremely-high frequency.
EL—Elevation.
EMCON—Emission control.
F
FDM—Frequency division multiplexing.
FDMA—Frequency division multiple access.
FDX—Full duplex.
FFN—Fleet flash net.
FLTCINC—Fleet Commander-in-Chief.
FLTSATCOM—FM satellite communications.
FOT—Frequency of optimum transmission.
FSB—Fleet satellite broadcast.
FSK—Frequency-shift keying.
G
GHz—Gigahertz.
H
HDX—Half duplex.
HERO—Hazardous electromagnetic radiation.
HF—High frequency.
HPA—High-power amplifier.
Hz—Hertz.
I
IF—Intermediate frequency.
K
kHz—Kilohertz.
L
LEASAT—Leased satellite.
LF—Low frequency.
LNA—Low-noise amplifier.
LOS—Line of sight.
LP—Log-periodic antenna.
LPI—Low probability of intercept.
LSTDMs—Low-speed time division multiplexer.
LUF—Lowest usable frequency.
M
MHz—Megahertz.
MF—Medium frequency.
MPA—Medium power amplifier.
MUF—Maximum usable frequency.
N
NATO—North Atlantic Treaty Organization.
NAVCOMTELSTA—Naval Computer andTelecommunications station.
NAVMACS—Naval Modular AutomatedCommunications System.
AII-1
NCTAMS—Naval Computer andTelecommunications Area Master Station.
NCTS—Naval Computer and Telecommunicationsstations.
NECOS—Net control station.
O
ORESTES—Teleprinter subsystem.
OTAR—Over-the-air relay.
OTAT—Over-the-air transfer.
OTC—Officer in tactical command.
OTCIXS—Officer in Tactical Command InformationExchange Subsystem.
P
PRIS/S—Primary ship-shore.
PSK—Phase shift keying.
R
RADHAZ—Radiation hazard.
RF—Radio frequency.
RLP—Rotatable log-periodic antenna.
S
SAR—Search and air rescue.
SATCOM—Satellite communication.
SECVOX—Secure voice.
SHF—Super-high frequency.
SSB—Single-sideband.
SSIXS—Submarine Satellite Information ExchangeSubsystem.
T
TACINTEL—Tactical intelligence system.
TADIXS—Tactical Data Information ExchangeSubsystem.
TDM—Time division multiplexing.
TDMA—Time division multiple access.
U
UHF—Ultra-high frequency.
V
VHF—Very-high frequency.
VLF—Very-low frequency.
AII-2
APPENDIX III
REFERENCES USED TO DEVELOPTHIS NRTC
Basic Operational Communications Doctrine (U), NWP 4(B), Chief of Naval Operations,Washington, D.C., Sep. 1989.
Communication Instructions—General (U), ACP 121(F), Joint Chiefs of Staff, Washington,D.C., Apr. 1983.
Communications Instructions—General, ACP 121 US SUPP-l(F), Joint Chiefs of Staff,Washington, D.C., June 1981.
Communications Instructions—Teletypewriter (Teleprinter) Procedures, ACP 126(C), JointChiefs of Staff, Washington, D.C., May 1989.
Communications Security Material System (CMS) Policy and Procedures Manual, CMS 21,Department of the Navy, Washington, D.C., June 2000.
Fleet Communications (U), NTP 4(D), Commander, Naval Telecommunications Command,Washington, D.C., Feb. 1995.
Naval Telecommunications Procedures, Recommended Frequency Bands and FrequencyGuide, NTP 6 Supp-l(S), Commander, Naval Computer and TelecommunicationsCommand, Washington, D.C., 1993.
Naval Telecommunications Procedures, Spectrum Management Manual, NTP 6(D),Commander, Naval Telecommunications Command, Washington, D.C., Aug. 1992.
Naval Warfare Documentation Guide, NWJP 0 (Rev. P)/NWP 1-01, Chief of NavalOperations, Washington, D.C., Jan. 1990.
Navy Electricity and Electronics Training Series, Module 1, Introduction to Matter, Energy,and Direct Current, NAVEDTRA 14173, Naval Education and Training ProfessionalDevelopment and Technology Center, Pensacola, Fla., 2003.
Navy Electricity and Electronics Training Series, Module 2, Introduction to AlternatingCurrent and Transformers, NAVEDTRA 14174, Naval Education and TrainingProfessional Development and Technology Center, Pensacola, Fla., 2003.
Navy Electricity and Electronics Training Series, Module 8, Introduction to Amplifiers,NAVEDTRA 14180, Naval Education and Training Professional Development andTechnology Center, Pensacola, Fla., 1998.
Navy Electricity and Electronics Training Series, Module 9, Introduction toWave-Generation and Wave-Shaping Circuits, NAVEDTRA 14181, Naval Educationand Training Professional Development and Technology Center, Pensacola, Fla., 1998.
Navy Electricity and Electronics Training Series, Module 10, Introduction to WavePropagation, Transmission Lines, and Antennas, NAVEDTRA 14182, Naval Educationand Training Professional Development and Technology Center, Pensacola, Fla., 1998.
Navy Electricity and Electronics Training Series, Module 12, Modulation Principles,NAVEDTRA 14184, Naval Education and Training Professional Development andTechnology Center, Pensacola, Fla., 1998.
AIII-1
Navy Electricity and Electronics Training Series, Module 17, Radio-FrequencyCommunications Principles, NAVEDTRA 14189, Naval Education and TrainingProfessional Development and Technology Center, Pensacola, Fla., 1998.
Navy Occupational Safety and Health (NAVOSH) Program Manual for Forces Afloat, Vols I,II, and III, OPNAVINST 5100.19D, Chief of Naval Operations, Washington, D.C., Aug.2001.
Navy Super-High Frequency Satellite Communications, NTP 2, Section 1 (E), NavalComputer and Telecommunications Command, Washington, D.C., Jan. 2001.
Navy UHF Satellite Communication System Description, IWCS-200-83-1, Commander,Naval Ocean Systems Center, San Diego, Calif., 1991.
Navy UHF Satellite Communication System—Shipboard, EE130-PL-OMI-010/W142-UHFSATCOM, Space and Naval Warfare Systems Command, Washington, D.C., Aug. 1986.
Navy Ultra-High Frequency Satellite Communications (U), NTP 2, Section 2 (E), NavalComputer and Telecommunications Command, Washington, D.C., July 1992.
Operational Reports, NWP 1-03.1, Chief of Naval Operations, Washington, D.C., Nov.1987.
Secure Telephone Unit Third Generation (STU-III) COMSEC Material ManagementManual, CMS 6, Director, Communications Security Material System, Washington,D.C., Oct. 1990.
Shipboard Antenna Systems, Volume 1, Communications Antenna Fundamentals,NAVSHIPS 0967-17-3010, Naval Ship Systems Command, Washington, D.C., Sep.1972.
Shipboard Antenna Systems, Volume 3, Antenna Couplers, Communications AntennaSystems, NAVSHIPS 0967-177-3030, Naval Ship Systems Command, Washington, D.C., Jan. 1973.
Shipboard Antenna Systems, Volume 5, Antenna Data Sheets, SPAWAR 0967-LP-177-3050, Space and Naval Warfare Systems Command, Washington, D.C., May1973.
Ships’ Maintenance and Material Management (3-M) Manual, OPNAVINST 4790.4C,Chief of Naval Operations, Washington, D.C., Nov. 1994.
Telecommunications Users Manual, NTP 3(I), Commander, Naval TelecommunicationsCommand, Washington, D.C., Jan. 1990.
AIII-2
INDEX
A
Antennas, 2-15broadband, 2-18conical monopole, 2-21emergency, 2-22inverted cone, 2-22log-periodic, 2-22multiwire rhombic, 2-21quarter-wave, 2-16rhombic, 2-21SATCOM, 2-19sleeve, 2-21tuning, 2-14, 2-15, 2-17, 2-25UHF, 2-18VHF, 2-18whip, 2-17wire rope, 2-17
Antenna coupling, 2-25Antenna distribution system, 2-23Antenna positioning, 2-24
align for optimum reception, 2-25rotate for optimum reception, 2-24tune for optimum reception, 2-25use, 2-24
Antenna systems, 2-12ASWIXS, 2-10AUTOCAT, 2-12bidirectional, 2-12characteristics, 2-12directivity, 2-12dummy load, 2-14feed point, 2-12incident waves, 2-14omnidirectional, 2-12reciprocity, 2-12reflected waves, 2-14unidirectional, 2-12wave polarization, 2-13
C
COMMSPOT reports, 1-6Cryptographic equipment, 1-4
frequency-shift keying (FSK), 1-4CUDIXS, 1-6, 2-13
D
DAMA, 2-11
Distress communications, 1-7emergency, 2-26frequencies, 1-7OTC, 1-15SAR frequencies, 1-7watches, 1-7
Dummy load, 2-14
E
EHF, 2-5Electromagnetic wavelength, 2-15
full wave, 2-16half wave, 2-15quarter wave, 2-16
F
FDMA, 2-5Feed point, 2-12
center-fed, 2-12end-fed, 2-12mid-fed, 2-12
FFN, 2-12Fleet broadcast system, 2-9Fleet broadcast system equipment, 2-9
AM-6534/SSR-l amplifier-converter, 2-6AN/ARC-143 UHF transceiver, 2-6AN/FSC-79 Fleet Broadcast terminal, 2-6AN/SSR-l receiver, 2-6AN/WSC-3 (UHF) transceiver, 2-6AN/WSC-5 (UHF) transceiver, 2-6Antisubmarine Warfare Information Exchange
Subsystem (ASWIXS), 2-7Fleet Satellite Broadcast (FSB), 2-9MD-900/SSR-l combiner-demodulator, 2-6TD-1063/SSR-1 demultiplexer, 2-6
Fleet Satellite Communications (FLTSATCOM), 2-5Antisubmarine Warfare Information Exchange
Subsystem (ASWIXS), 2-7circuit restoral/coordination, 2-11Common User Digital Information Exchange
System (CUDIXS), 2-9Control subsystem, 2-10Demand Assigned Multiple Access (DAMA), 2-11Fleet Flash Net (FFN), 2-12Fleet Satellite Broadcast, (FSB), 2-9LEASAT telemetry tracking and command
subsystem, 2-10
INDEX-1
Naval Modular Automated CommunicationsSystem (NAVMACS), 2-10
Officer in Tactical Command InformationExchange Subsystem (OTCIXS), 2-10
Secure voice, 2-10special circuits, 2-11Submarine Satellite Information Exchange
Subsystem (SSIXS), 2-9Tactical Data Information Exchange Subsystem,
(TADIXS), 2-10Tactical Intelligence subsystem, 2-10Teleprinter Subsystem (ORESTES), 2-10FLTSATCOM, 2-10
Frequency-shift keying (FSK), 1-4FSB, 2-9Full-period terminations, 1-5
CUDIXS, 1-6equipment tests, 1-6NAVMACS, 1-6TACINTEL, 1-6termination requests, 1-5termination types, 1-6
G
GPS, 1-5
H
Hazardous electromagnetic radiation (HERO), 1-5High-frequency receive system, 1-2High-frequency transmit systems, 1-2HPA, 2-6
L
LNA, 2-6Low-frequency systems, 1-2LPI, 2-6
M
MARCONI antenna, 2-19MIDDLEMAN, 2-12MPA, 2-6
low-speed time division multiplexer (LSTDMs),2-6
N
NAVMACS, 2-9, 2-10
O
Optimum reception, 2-25tuning, 2-25
ORESTES, 2-10OTAT/OTAR, 1-6OTCIXS, 2-10Over-the-air rekey, 1-6Over-the-air transfer, 1-6
P
Patch panels, 1-3Primary ship-shore circuits, 1-6
FSK, 1-6PSK, 1-6, 2-7
Q
Quality monitoring, 1-8AN/SSQ-88 equipment, 1-10AN/SSQ-88 quality monitoring set, 1-9program, 1-8system, 1-8
R
RF safety precautions, 2-26burns, 2-25dielectric heating, 2-27precautions, 2-27warning signs, 2-27
S
SATCAT, 2-14SATCOM antennas, 2-1
AS-29151SSR-1, 2-19DAMA, 2-11frequency division multiple access (FDMA), 2-5FLTSATCOM, 2-2GAPFILLER, 2-1LEASAT, 2-3low-speed time division multiplexer (LSTDMs),
2-6OE-83C/WSC-l(V) group, 2-19phase shift keying (PSK), 2-7pointing guide, 2-3time division multiple access (TDMA), 2-5types, 2-1
SATCOM system, 2-5
INDEX-2
Fleet Broadcast System, 2-9Fleet Satellite Communications, 2-7high-power amplifier (HPA), 2-6low-noise amplifier (LNA), 2-6low-probability of intercept (LPI), 2-6medium-power amplifier (MPA), 2-6secure voice worldwide voice network, 1-5net membership, 1-5satellite system control, 1-5
Ship-shore circuits, 1-4duplex, 1-4full duplex (FDX), 1-4half duplex (HDX), 1-4methods, 1-10semiduplex, 1-4simplex, 1-4
Special circuits, 2-11AUTOCAT, 2-12MIDDLEMAN, 2-12SATCAT, 2-12
SSIXS, 2-9
Status board, 1-7Super-high frequency systems, 1-3
T
TACINTEL, 1-6, 2-13TADIXS, 2-12TDMA, 2-5
U
Ultra-high frequency systems, 1-2Ultra-high frequency receive system, 1-2Ultra-high frequency transmit system, 1-5Underway preparation, 1-1
predeployment check-off sheet, 1-1
V
Very-high frequency systems, 1-2
INDEX-3
ASSIGNMENT 1
1-1. A lot of communications failures are ascribedto which of the following areas?
1. Equipment failure2. Poor administration3. Technical problems4. Operator error
1-2. The level of readiness and preparation that adeploying ship should maintain is determinedby what individual?
1. The commanding officer2. The executive officer3. The type commander4. The fleet commander in chief
1-3. The most efficient method of ensuring that allstep-by-step preparations are completed beforedeploying can be accomplished by usingwhich of the following procedures?
1. A check-off list2. A visual check of all stores3. A review of all locally produced SOPs4. A review of all inventory lists
1-4. What publication provides the minimumnumber of check-off sheets?
1. NTP 42. NWP 43. CMS 14. CMS 5
1-5. For long-range direction finding,medium-range communications andnavigation communications, which of thefollowing frequencies is normally used?
1. VLF2. UHF3. SHF4. LF
1-6. What frequency band is used as a backupsystem for satellite communication systems?
1. 30-300 kHz2. 3-30 MHz3. 30-300 MHz4. 300 Mhz to 3 GHz
1-7. What frequency band is used strictly forline-of-sight communications?
1. SHF2. EHF3. LF4. HF
1-8. What is the difference, if any, between a blackdc patch panel and a red dc patch panel?
1. The black dc patch panel is located closerto the antenna multicoupler than the red dcpatch panel
2. The black dc patch panel allows theoperator to patch the signal to any cryptoequipment, and the red dc patch panelrestricts the printer selected to plainreadable text or language
3. The black dc patch panel allows forpatching the signal into any cryptoequipment, and the red dc patch panelcompletes the loop for a single feedbackcircuit
4. None
1-9. What frequency range is primarily for mobileand maritime units?
1. UHF2. SHF3. HF4. VLF
1-10. Aeronautical radio navigation, mobilecommunications, boat crews, and radar usewhich of the following frequency bands?
1. ELF2. HF3. VLF4. VHF
1-11. Which of the following satellite systemsegments has been designed to counterspoofing?
1. Space2. Terminal3. Control4. Each of the above
1
Textbook Assignment: “Communications Hardware,” chapter 1, pages 1-1 through 1-10.
1-12. The UHF band is located in what frequencyrange?
1. 30 - 300 GHz2. 300 MHz to 3 GHz3. 3 - 30 MHz4. 300 kHz to 3 MHz
1-13. Which of the following patch panel colorsindicates classified material is being passedthrough the panel?
1. Black2. Blue3. Red4. Green
1-14. “A sequence of random binary bits used toinitially set and periodically changepermutations in crypto equipment fordecrypting electronic signals” defines whatterm?
1. Key2. Cipher text3. Secure system process4. Enciphered signal
1-15. Information pertaining to the Navy’s SHFsatellite system can be found in what sectionof NTP 2?
1. One2. Two3. Three4. Four
1-16. What is/are the warning sign(s), if any, that areattached to black patch panels?
1. UNCLAS ONLY2. ENCRYPTED TRAFFIC ONLY3. BLACK PATCH PANEL and UNCLAS
ONLY4. None
1-17. Equipment permanently wired together andused in conjunction with each other is knownby which of the following terms?
1. Normal-through2. Wired3. Tied4. Junctions
1-18. The Navy’s primary means of deliveringmessage traffic to afloat commands isaccomplished through use of which of thefollowing ship-shore circuits?
1. Full period terminations2. SSIXS3. Fleet broadcast4. OTIXS
1-19. What term used in the call-up indicates that aship cannot transmit and receivesimultaneously?
1. Duplex2. Simplex3. Semiduplex4. Voice only
1-20. What type of publications contain informationand instructions on the use of cryptoequipment?
1. KAOs2. NTPs3. NWPs4. ACPs
1-21. Under HERO conditions, the affected shipcommunicates to other ships using whatfrequency band?
1. HF2. SHF3. UHF4. EHF
1-22. Which of the following is NOT a requirementwhen on a secure voice net?
1. Paper logs must be used2. HF transmitter tuning is prohibited3. Dummy load calibrations must be used4. Actual time of significant transmissions
must be logged
1-23. On a secure voice net, the NECOS normallyensures proper circuit discipline.
1. True2. False
1-24. What are the different methods of operation inship-shore mode?
1. Duplex, simplex, and semiduplex2. Simplex, semiduplex, and triplex3. Duplex, semiduplex, and quadplex4. Simplex, duplex, triplex, and quadplex
2
1-25. When you can use a communicationsequipment to both transmit and receivesimultaneously, this is known by which of thefollowing terms?
1. FSK (phase shift keying)2. TDM (time-division multiplexing)3. FDX (full duplex)4. HFX (half duplex)
1-26. What is the normal reason that a ship woulduse the simplex method?
1. Equipment casualties2. Not ample equipment onboard3. Abundance of circuits online4. Transmission by NECOS of a SAR request
1-27. A ship using a simplex system has to call upthe shore station to pass message traffic. If theship cannot raise the shore station after thesecond attempt, what is the usual procedure?
1. Check the equipment2. Repeat the call-up3. Try standby frequency4. Attempt to contact another station
1-28. What is the purpose of the secure voiceworldwide voice network?
1. To be able to communicate anywhere inthe world by voice
2. For ships to be able to talk to shore stations3. To hook together all types of commands
into one voice network4. To provide secure real-time, voice
communications between both afloatcommands and operational commandersusing HF or satellite connectivity
1-29. What is the total number of FLTCINCs thatcontrol the network of secure voice areacontrol stations?
1. One2. Two3. Three4. Four
1-30. What does a full-period terminationaccomplish?
1. Provides communications between shorestations and afloat commands
2. Allows a ship to send traffic to any shorestation along its track for retransmission
3. Provides exercise control over a ship for agreater period of time
4. Allows a ship and an aircraft tocommunicate over greater distances
1-31. What is the normal lead time that atermination request must be submitted for afull-period termination?
1. 12 hours2. 24 hours3. 36 hours4. 48 hours
1-32. Details that must be included in a terminationrequest message are in what publication?
1. NTP 32. NTP 43. NWP 44. NWP 6
1-33. Once the full-period termination period issecured, what type of message must be sent tocancel the termination?
1. TSR2. COMMSPOT3. COMMSHIFT4. Off-the-air
1-34. System back-to-back off-the-air testing mustbe completed what total number of hoursbefore a termination activation?
1. 12 hrs2. 24 hrs3. 48 hrs4. 72 hrs
1-35. For what reason will a COMMSPOT report besubmitted?
1. Any time unusual communicationsdifficulties are encountered
2. When a ship is having problems passingtraffic to a shore station
3. When a shore station cannot raise a shipfor a channel check
4. When an aircraft wishes to pass vitalmessage traffic for a Task Force
3
1-36. To prepare a JINTACCS formattedCOMMSPOT message, you should refer towhat publication for instructions?
1. NTP 42. CMS 63. NWP 1-03, Supp-14. NWP 10-10-10 (NWP 1-03.1)
1-37. Primary ship-shore circuits use what type ofencrypted teleprinter nets?
1. TDM/TDK2. FDX/HDX3. ARK/MRK4. PSK/FSK
1-38. Where are the frequencies for PRI S/S circuitslisted?
1. CIBs2. TSRs3. NAVADMINs4. Local SOPs
1-39. What does the use of OTAT/OTAR proceduresallow a command to do?
1. Not carry any crypto keying material2. Reduce the amount of paper keying
material on board3. Relieve the operator of ever using SF-153
forms4. Reduce the number of CMS custodians
required
1-40. In what publication do you find detailedOTAT/OTAR procedures?
1. CMS 12. CMS 63. NAG 164. NTP 4
1-41. Where were the use and verification ofOTAT/OTAR procedures first used?
1. Desert Shield/Storm2. Vietnam3. Bosnia4. Cuba
1-42. What type of message traffic takes priorityover all other types?
1. Immediate2. AMCROSS3. Distress4. SOSUS
1-43. Who may authorize the transmission ofunclassified distress messages on national orinternational distress frequencies?
1. The commanding officer2. The officer in tactical control3. The communications officer4. The communications watch officer
1-44. If your ship is in distress and traveling withothers, to whom will you transmit yourdistress message?
1. FLTCINC2. OTC3. NECOS4. CNO
1-45. If you are in a lifeboat, which of the followingfrequencies will you use?
1. 500 kHz2. 2182 kHz3. 8364 kHz4. 121.5 MHz
1-46. What is the international worldwide SARfrequency for voice?
1. 138.78 MHz2. 123.1 MHz3. 282.8 MHz4. 172.5 MHz
1-47. Navy ASW aircraft assigned to a SAR missionmonitor on what frequency?
1. 138.78 MHz2. 123.1 MHz3. 282.8 MHz4. 172.5 MHz
1-48. During an emergency, which of the followingorganizations/officers is in control of thedistress message traffic frequency?
1. The station in distress2. The first ship on the scene3. The first aircraft on the scene4. The senior international officer at the scene
1-49. When equipment and manpower will allow,what frequencies does a watch stationnormally listen to?
1. Worldwide timing2. GMT3. Distress4. Secvox
4
1-50. What is the usual cause of systemdegradation?
1. Dirty jacks2. Small contributing factors3. Power outages4. Degraded patch cords
1-51. What is the primary function of the qualitymonitoring program?
1. To ensure that all PMS checks arecompleted on line
2. To monitor the end results from all QCjobs
3. To verify all paper work associated withlevels, signals, and analysis forms
4. To direct measurement of signal qualitycharacteristics
1-52. What is the nomenclature of the QualityMonitoring set?
1. AN/SSQ-882. AN/QMS-233. Spectrum Analyzer 1344. Spectrum Monitor 143
5
ASSIGNMENT 2
2-1. What was the reason for the development ofthe satellite communication (SATCOM)system?
1. Provides a long range, jam-proofcommunication system
2. Fulfills the military requirements forreliable, high-capacity, secure andcost-effective telecommunications
3. Is line-of-sight and EMCON proof4. Replaces all baseband frequencies during
HERO and AUTOCAT
2-2. Satellites provide an alternative to which ofthe following facilities?
1. Fixed ground installations2. Airborne command posts3. GPS4. AMCC vans
2-3. What are the three types of U.S. Navy com-munications satellites?
1. MARISAT, RCA, and ATT2. GAPFILLER, FLTSATCOM, and
LEASAT3. ORION, EROS and ZEUS4. DANTES, ORION, and HERMES
2-4. What type of orbits do U.S. Navy satellitesuse?
1. Geostationary2. Geosynchronous3. Polar4. Random
2-5. MARISAT channels are broken down intothree UHF channels, two narrowbandchannels, and what total number of widebandchannels?
1. One2. Five3. Three4. Six
2-6. The 500-kHz band GAPFILLER satellitesprovide what number of 75-baud ship-shorecommunications channels?
1. 152. 203. 354. 50
2-7. What does the UHF receiver separate on theGAPFILLER satellite?
1. The receiver and transmitter band2. Intermediate frequencies and low
frequencies3. Secure voice and non-secure voice
channels4. Red and Black channels
2-8. What are the FLTSATCOM satellites’longitudinal positions?
1. 95° W, 65° E, and 150° E2. 25° E, 35° W, 05° N, and 55° E3. 100° W, 72.5° E, 23° W, and 172° E4. 22° W, 152° E, 06° E, and 21° N
2-9. What is the maximum RF-channel capabilityon the FLTSATCOM satellite?
1. 102. 153. 234. 35
2-10. On the FLTSATCOM satellite, channel 1 ofthe 25-kHz channels is used for what purpose?
1. Timing2. Fleet broadcast3. Weather4. DSN
2-11. What is the position of the LANT (L-1)LEASAT?
1. 15° W2. 105° W3. 72.5° E4. 53° E
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Textbook Assignment: “Satellites and Antennas,” chapter 2, pages 2-1 through 2-28.
2-12. Each LEASAT provides what total number of(a) communications channels and (b)transmitters?
1. (a) 10 (b) 42. (a) 11 (b) 63. (a) 13 (b) 94. (a) 15 (b) 11
2-13. One of the UHF downlink channels is used forthe Fleet Satellite Broadcast downlink. Whatis its frequency?
1. 10 kHz2. 15 kHz3. 20 kHz4. 25 kHz
2-14. A Demand Assigned Multiple Access(DAMA) modem replaced which of thefollowing terminals on aircraft carriers?
1. TADIX2. QUICKSAT3. SUBSAT4. FSC-78
2-15. What are the two types of communicationsatellites?
1. Active and passive2. Passive and module3. Active and repeater4. Repeater and passive
2-16. An active satellite and two Earth terminals areconsidered what type of operational link?
1. Standard2. Optimal3. Universal4. Typical
2-17. Normally, a satellite’s orbit is elliptical orcircular, while its incline is polar, equatorial,or which of the following?
1. Angle2. Attitude3. Inclined4. Slant
2-18. A satellite communications system includesinstalled communications receivers andtransmitters and what other components?
1. Two Earth terminals ready to transmit andreceive satellite signals
2. Two Earth terminals equipped withreceiver and satellite transceivers
3. Three Earth terminals, two with receiversand one with transceivers
4. Three Earth terminals, one with receiversand two with UHF transmitters
2-19. What capability does a narrow uplinktransmission beamwidth provide?
1. High intercept problems (HIP)2. Low probability of intercept (LPI)3. High detection rates (HDR)4. Exploitation, detection, and location
(EDL)
2-20. An HPA or MPA, LNA, up and downconverters, and a frequency standard areknown by what name?
1. Power group2. Digital set3. Binary set4. Radio group
2-21. What is the Navy’s standard SATCOMbroadcast receiver system?
1. AN/FSC-792. AN/SSR-13. CV-1234. ARC-143B
2-22. Communications subsystems and satellites areinterfaces using which of the followingequipments?
1. AM-65342. TD-10633. AN/FSC-794. CV-123
2-23. What is the operating bandwidth of theAN/FSC-79?
1. 7 to 8 GHz2. 9 to 11 GHz3. 10 to 12 GHz4. 11 to 15 GHz
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2-24. When it uplinks in the 292.2- to 311.6 MHzbandwidth and downlinks in the 248.5- to270.1 MHz band, the AN/WSC-3 is in whatmode of operation?
1. TDM2. Fleet communication3. SATCOM4. Remote
2-25. The AN/ARC-143 UHF Transceiver, used forASWIXS communications, has how manyparts?
1. Five2. Two3. Three4. Four
2-26. What type of system provides communicationslinks, via satellite, between mobile units andshore commands?
1. FLTSATCOM2. LEASAT3. NOVEMBER4. DELTA
2-27. What network/terminal is used as the interfacebetween CUDIXS (shore-based) and the FleetBroadcast System?
1. SNAP III2. NAVMACS3. GLOBAL HICOM4. DAMA
2-28. SSIXS is used to transmit and receive messagetraffic between what two types of users?
1. VP aircraft and ASCOMMs2. Fleet Marine Forces and attack helos3. SSN/SSBN submarines and shore stations4. SSN/SSBN submarines and Battle Group
commanders
2-29. ASWIXS is used as a communications linkbetween ASW planes during operations andwhat other type of commands?
1. Shore stations2. Battle Group commanders3. Senior officer present afloat4. SPECOMMs
2-30. The subsystem that expedites status reportingand management of FLTSATCOM systemassets is known by what name?
1. TACINTEL2. NECOS3. Control4. Fleet Flash Net
2-31. DAMA was developed for what purpose?
1. To break out the secure voice circuit fromall other transmissions
2. To remove all residue traces that allow forjamming
3. To fully automate and link data systemswith the net
4. To multiplex several subsystems onto onesatellite channel
2-32. What other multiplexing method, if any, doesthe Navy use besides frequency-division?
1. Time-division2. Shift-division3. Split time-division4. None
2-33. When HERO condition and EMCONrestrictions are set, what are the radiofrequencies (RFs) that are prohibited fromuse?
1. 2 - 3 GHz2. Below 30 MHz3. 300 - 2568 kHz4. Above 3000 kHz
2-34. Who are the major participants on the FFN?
1. Senior operational staffs only2. Senior operational staffs and designated
subscribers3. NATO and CINCs only4. The Joint Chiefs of Staff and their Force
Commanders
2-35. An antenna can both transmit and receiveenergy. This ability is known by what term?
1. Reciprocity2. Feed point3. Transducance4. Stagnation
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2-36. The point on an antenna where the RF cable isattached is known by what term?
1. Focal point2. Dummy point3. Feed point4. Center point
2-37. What type of antenna radiates efficiently inonly one direction?
1. Bidirectional2. Omnidirectional3. Polarized4. Unidirectional
2-38. Energy reflected back to the feed point isknown by which of the following terms?
1. Impedance point2. Reflected waves3. Oscillation point4. Deflected waves
2-39. Electromagnetic waves travel in free space atwhat rate?
1. 1,324,000 miles per second2. 946,000 miles per second3. 518,000 miles per second4. 186,000 miles per second
2-40. Antennas are referred to in lengths. There isfull quarter, and which of the following otherlengths?
1. Half2. Eighth3. Third4. Sixteenth
2-41. Wire rope (fan) antennas are used for whatrange of frequency coverage?
1. 30 kHz to 299 kHz2. 300 kHz to 30 MHz3. 2 - 20 GHz4. 3 - 30 kHz
2-42. What antenna is used with the AN/WSC-3transceiver and is employed primarily onboardships?
1. AN/SSR-12. OE-82C/WSC-1(V)3. Whip4. Quarter-wave
2-43. Where is the OE-82/WSC-1(V) mounted?
1. Main stack2. Fore mast3. On a pedestal4. To the skin of the ship
2-44. What is the receiving frequency band for theOE-82C/WSC-1(V)?
1. 248 - 272 MHz2. 275 - 300 MHz3. 310 - 315 MHz4. 2 - 4 GHz
2-45. What is the total number of AS-2815/SSR-1antennas in an AN/SRR-1 receiver system?
1. One2. Two3. Three4. Four
2-46. The AS-2815/SSR-1 antennas employed in the240- to 315-MHz frequency range are used toreceive what type of broadcasts?
1. CUDIXS2. Common Channel3. FFN4. Fleet
2-47. What is the physical size of the newer satelliteparabolic antennas?
1. 6 in2. 8 in3. 12 in4. 18 in
2-48. The conical monopole antenna is used in whattype of communications?
1. LF2. MF3. HF4. VHF
2-49. The AN/SRA-12 allows for what total numberof RF channels in the 14-kHz to 32-MHzrange?
1. Five2. Two3. Seven4. Four
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2-50. What is/are the objectives of tuning anantenna?
1. Tune out impedances and match length tofrequency radiated
2. Physically or mechanically move theantenna
3. Exhibit and multiplex its impedance4. Clean up the wave generation and use
wave propagation
2-51. Which Navy standards, if any, have controlover the safety of personnel going aloft?
1. NAVSAFCEN instructions2. NAVOSH requirements3. MILSTDs4. None
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