rfi management for single dish radio astronomy at nrao green bank
DESCRIPTION
RFI Management for Single Dish Radio Astronomy at NRAO Green Bank. Some Considerations. Single dish RA is more vulnerable to RFI than array configurations. Protection and source-mitigation are the preferred options but not always possible. - PowerPoint PPT PresentationTRANSCRIPT
RFI Management for Single Dish Radio Astronomy
at NRAO Green Bank
Some ConsiderationsSome Considerations
Single dish RA is more vulnerable to Single dish RA is more vulnerable to RFI than array configurations.RFI than array configurations.
Protection and source-mitigation are Protection and source-mitigation are the preferred options but not always the preferred options but not always possible.possible.
Weak, narrowband, or intermittent Weak, narrowband, or intermittent RFI lends itself to excision; strong, RFI lends itself to excision; strong, constant, or wideband noise-like RFI constant, or wideband noise-like RFI does not.does not.
Protection and MitigationProtection and Mitigation
National/International (Protected National/International (Protected Bands)Bands)
Regional (NRQZ)Regional (NRQZ) State (WVRAZ)State (WVRAZ) Site (Site Policy)Site (Site Policy)
NTIA Radio Astronomy Allocated BandsNTIA Radio Astronomy Allocated Bands
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive Primary
Radio Astronomy Frequency Allocations in the United States
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive Primary
Radio Astronomy Frequency Allocations in the United States
NTIA Radio Astronomy Allocated BandsNTIA Radio Astronomy Allocated Bands
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive PrimaryShared Primary
Radio Astronomy Frequency Allocations in the United States
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive Primary
Shared Primary
Radio Astronomy Frequency Allocations in the United States
NTIA Radio Astronomy Allocated BandsNTIA Radio Astronomy Allocated Bands
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive PrimaryShared Primary
Secondary
Radio Astronomy Frequency Allocations in the United States
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive Primary
Shared Primary
Secondary
Radio Astronomy Frequency Allocations in the United States
NTIA Radio Astronomy Allocated BandsNTIA Radio Astronomy Allocated Bands
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive PrimaryShared Primary
SecondaryFootnote
Radio Astronomy Frequency Allocations in the United States
3 MHz 30 MHz
30 MHz 300 MHz
300 MHz 3 GHz
3 GHz 30 GHz
30 GHz 300 GHz
Exclusive Passive Primary
Shared Primary
Secondary
Footnote
Radio Astronomy Frequency Allocations in the United States
The National Radio Quiet ZoneThe National Radio Quiet Zone
Established by an Established by an act of congress in act of congress in 19581958
Approx. 13,000 sq. Approx. 13,000 sq. mile areamile area
Requires Requires coordination for all coordination for all permanent, fixed, permanent, fixed, licensed licensed transmitterstransmitters
Administered Administered through NRAO through NRAO Green Bank for the Green Bank for the mutual benefit of mutual benefit of NRAO and the NRAO and the Sugar Grove FacilitySugar Grove Facility
WV Radio Astronomy ZoneWV Radio Astronomy Zone
Established through §37A-Established through §37A-1-2 of the West Virginia 1-2 of the West Virginia Code “The Radio Astronomy Code “The Radio Astronomy Zoning Act”Zoning Act”
Applies to any electrical Applies to any electrical equipment that causes equipment that causes harmful interference to harmful interference to Radio Astronomical Radio Astronomical ObservationsObservations
Increasingly difficult and Increasingly difficult and complex problem due to the complex problem due to the proliferation of wireless proliferation of wireless technologiestechnologies
Our Strategy: Our Strategy: • Problem-driven component: Problem-driven component:
we will seek enforcement we will seek enforcement only as a last resort, if only as a last resort, if friendly requests friendly requests repeatedly fail.repeatedly fail.
• Proactive component: We Proactive component: We solicit voluntary solicit voluntary cooperation: PR campaign cooperation: PR campaign is in progress to raise is in progress to raise awareness awareness
Zones 1 & 2: On-Site RFI PolicyZones 1 & 2: On-Site RFI Policy
IPG Develops Policy; Site Director has final authorityIPG Develops Policy; Site Director has final authority ITU-R RA.769 Limit appliesITU-R RA.769 Limit applies
ITU-R RA.769 Limit @ Jansky Lab (1801 m from GBT prime focus)
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
10 100 1000 10000 100000
Frequency (MHz)
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ITU-R RA.769 Line Limit @Jansky Lab IRP (dBm)
ITU-R RA.769 ContinuumLimit @ Jansky Lab IRP(dBm)
ITU-R RA.769 Limit @ 2-mile Radius
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
10 100 1000 10000 100000
Frequency (MHz)
Iso
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ITU-R RA.769 Line Limit @2miles IRP (dBm)
ITU-R RA.769 ContinuumLimit @ 2miles IRP (dBm)
ITU-R RA.769 Limit @ 10-mile Radius
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
10 100 1000 10000 100000
Frequency (MHz)
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ITU-R RA.769 Line Limit @10miles IRP (dBm)
ITU-R RA.769 ContinuumLimit @ 10miles IRP (dBm)
ITU-R RA.769 and NRQZ Limits @ 10-mile Radius
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
10 100 1000 10000 100000
Frequency (MHz)
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ITU-R RA.769 Line Limit @10miles IRP (dBm)ITU-R RA.769 ContinuumLimit @ 10miles IRP (dBm)NRQZ Limit @ 10miles IRP(dBm)
ITU-R RA.769, NRQZ and FCC Class B Limits @ 10-mile Radius
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
10 100 1000 10000 100000
Frequency (MHz)
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ITU-R RA.769 Line Limit @10miles IRP (dBm)ITU-R RA.769 ContinuumLimit @ 10miles IRP (dBm)NRQZ Limit @ 10miles IRP(dBm)FCC Class B Limit IRP(dBm)
ITU-R RA.769, NRQZ and FCC Class B Limits @ 2-mile Radius
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
10 100 1000 10000 100000
Frequency (MHz)
Iso
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ITU-R RA.769 Line Limit @2miles IRP (dBm)ITU-R RA.769 ContinuumLimit @ 2miles IRP (dBm)NRQZ Limit @ 2miles IRP(dBm)FCC Class B Limit IRP(dBm)
ITU-R RA.769, NRQZ, FCC Class B, and FCC Part 15 Intentional Radiator Limits @ 2-mile Radius
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
20.00
40.00
60.00
10 100 1000 10000 100000
Frequency (MHz)
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ITU-R RA.769 Line Limit @2miles IRP (dBm)ITU-R RA.769 ContinuumLimit @ 2miles IRP (dBm)NRQZ Limit @ 2miles IRP(dBm)FCC Class B Limit IRP(dBm)FCC part 15 IntentionalRadiator Limits IRP (dBm)
ITU-R RA.769 Limit @ Jansky Lab (1801 m from GBT prime focus)
-120.00
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
10 100 1000 10000 100000
Frequency (MHz)
Iso
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ITU-R RA.769 Line Limit @Jansky Lab IRP (dBm)
ITU-R RA.769 ContinuumLimit @ Jansky Lab IRP(dBm)
Assessing Equipment For RFI ComplianceAssessing Equipment For RFI ComplianceAnechoic Chamber TestingAnechoic Chamber Testing
Equipment Under Test (EUT)
Distance (Dtest)
Receive (Rx) Antenna
Cable #1
Amplifier
Cable #2
Cable #3
Spectrum Analyzer
PowerTx(dBm) = Pmeasured(dBm) + Lspace(dB) – Gantenna(dB) – Gamplifier(dB) + Lcables(dB)
ITU-R RA.769 Limit @ Jansky Lab (1801 m from GBT prime focus)
-120.00
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
10 100 1000 10000 100000
Frequency (MHz)
Iso
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pic
Ra
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Bm
)
ITU-R RA.769 Line Limit @Jansky Lab IRP (dBm)
ITU-R RA.769 ContinuumLimit @ Jansky Lab IRP(dBm)Anechoic ChamberSensitivity
ITU-R RA.769 Limit 150m from GBT prime focus
-140.00
-120.00
-100.00
-80.00
-60.00
-40.00
-20.00
0.00
10 100 1000 10000 100000
Frequency (MHz)
Iso
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ITU-R RA.769 Line Limit @150m IRP (dBm)
ITU-R RA.769 ContinuumLimit @ 150m IRP (dBm)
Anechoic ChamberSensitivity
The “Show Me” ProjectThe “Show Me” Project
~150m
The “Show Me” ProjectThe “Show Me” Project
~3:1 or 5dB SN Ratio…but anechoic chamber prediction said worst-case emissions exceed ITU-R line limit by 22dB....17dB discrepancy????
60s integration time of test vs. ITU-R line limit assumed 2000s integration:10Log(60/2000) = -15dB (close enough)