Radio-Quiet Zones Radio-Quiet Zones R. J. Cohen R. J. Cohen Jodrell Bank Observatory University of Manchester Jodrell Bank Observatory University of Manchester 13th June th June 2002

Susceptibility of Radio Astronomy Susceptibility of Radio Astronomy to Interference to Interference  Cosmic signals are weak (billions of times weaker than man-made signals) and noise-like 1 Jy = W/m 2 /Hz  Redshifts carry spectral lines to lower frequencies (because of expanding Universe)  Harmful interference levels are very low  Results of measurements are usually unpredictable: interference may look like new science  mm-wave receivers easily destroyed (1μm junctions) and filtering techniques are not mature Susceptibility of Radio Astronomy Susceptibility of Radio Astronomy to Interference to Interference  Cosmic signals are weak (billions of times weaker than man-made signals) and noise-like 1 Jy = W/m 2 /Hz  Redshifts carry spectral lines to lower frequencies (because of expanding Universe)  Harmful interference levels are very low  Results of measurements are usually unpredictable: interference may look like new science  mm-wave receivers easily destroyed (1μm junctions) and filtering techniques are not mature

Effective protection of radio astronomy requires coordinated action at all levels. The threats can be global, regional, national or local. Protection for Radio Astronomy - 1

  GLOBALLY - International Telecommunications Union (ITU) and Radio Regulations (quiet frequency bands for RA worldwide, limits on satellite emissions)   REGIONALLY - international agreements on harmonized spectrum use (e.g. how to share bands) and standards (good neighbours)   NATIONALLY – planning by telecommunications authority; spectrum management can create and maintain a radio-quiet zone   LOCALLY – remote site for observatory, liaise with local authorities about developments in RQZ   GLOBALLY - International Telecommunications Union (ITU) and Radio Regulations (quiet frequency bands for RA worldwide, limits on satellite emissions)   REGIONALLY - international agreements on harmonized spectrum use (e.g. how to share bands) and standards (good neighbours)   NATIONALLY – planning by telecommunications authority; spectrum management can create and maintain a radio-quiet zone   LOCALLY – remote site for observatory, liaise with local authorities about developments in RQZ Protection for Radio Astronomy - 2

ITU-R Rec. RA (RFI levels) 1. Radio astronomers should be encouraged to choose sites as free as possible from interference; 2. Administrations should afford all practicable protection to RA frequency bands, taking due account of the interference levels given in Annex 1; 3. Administrations should take all practicable steps to reduce unwanted emissions into RA bands, particularly from aircraft, spacecraft and balloons; 4. Administration should take into account the difficulties of sharing frequencies with transmitters in direct line-of-sight to observatories. ITU-R Rec. RA (RFI levels) 1. Radio astronomers should be encouraged to choose sites as free as possible from interference; 2. Administrations should afford all practicable protection to RA frequency bands, taking due account of the interference levels given in Annex 1; 3. Administrations should take all practicable steps to reduce unwanted emissions into RA bands, particularly from aircraft, spacecraft and balloons; 4. Administration should take into account the difficulties of sharing frequencies with transmitters in direct line-of-sight to observatories.

ITU-R Rec. RA (shared bands) 1. In making assignments administrations should take all practicable steps to avoid interference to RA; (e.g. don’t assign the frequencies to active services: shared bands don’t have to be shared!) 2. 2.Consideration be given to protecting RA sites by establishing coordination zones; (don’t assign the frequencies within a calculated distance of the radio observatory) 3. That the size of the coordination zone be calculated taking account of the protection criteria in Rec. RA and suitable propagation model. ITU-R Rec. RA (shared bands) 1. In making assignments administrations should take all practicable steps to avoid interference to RA; (e.g. don’t assign the frequencies to active services: shared bands don’t have to be shared!) 2. 2.Consideration be given to protecting RA sites by establishing coordination zones; (don’t assign the frequencies within a calculated distance of the radio observatory) 3. That the size of the coordination zone be calculated taking account of the protection criteria in Rec. RA and suitable propagation model.

ITU-R Rec. RA (above 60 GHz) 1. Coordination zones be established around mm- wave observatories, for all frequencies above 60 GHz where practicable; 2. 2.Until appropriate criteria are developed, use Rec RA.1031 to define size of coordination zone. Sharing with terrestrial services is possible at mm- wavelengths because of atmospheric attenuation, shielding by topography, and since there are only a small number of remote sites to protect. Also, at present the radio astronomers are almost the only people using the bands. ITU-R Rec. RA (above 60 GHz) 1. Coordination zones be established around mm- wave observatories, for all frequencies above 60 GHz where practicable; 2. 2.Until appropriate criteria are developed, use Rec RA.1031 to define size of coordination zone. Sharing with terrestrial services is possible at mm- wavelengths because of atmospheric attenuation, shielding by topography, and since there are only a small number of remote sites to protect. Also, at present the radio astronomers are almost the only people using the bands.

In-band transmitters: Most radio astronomy frequency bands are shared with active users (transmitters), some roaming! Need good coordination process. Out-of-band interference: Signals can leak into passive bands (pollution); powerful transmitters can block RA receiver (including IF amplifiers, e.g. IRAM radar). Need coordination of transmitters at any frequency. Non-radio transmitters: Electrical or electronic devices (e.g. computers, microwave ovens) – need better EMC standards In-band transmitters: Most radio astronomy frequency bands are shared with active users (transmitters), some roaming! Need good coordination process. Out-of-band interference: Signals can leak into passive bands (pollution); powerful transmitters can block RA receiver (including IF amplifiers, e.g. IRAM radar). Need coordination of transmitters at any frequency. Non-radio transmitters: Electrical or electronic devices (e.g. computers, microwave ovens) – need better EMC standards Need for Radio-Quiet Zones

Natural Radio Quiet Zones:  Sun-Earth Lagrangian point L 2  Shielded zone of Moon Terrestrial Radio Quiet Zones:  Typical radio observatory (Jodrell Bank)  Greenbank USA  SKA (possible Australian site)  ALMA Natural Radio Quiet Zones:  Sun-Earth Lagrangian point L 2  Shielded zone of Moon Terrestrial Radio Quiet Zones:  Typical radio observatory (Jodrell Bank)  Greenbank USA  SKA (possible Australian site)  ALMA Radio-Quiet Zones

VSA (Very Small Array) 14-element array at Observatorio del Teide (Tenerife) UK (Jodrell Bank and Cambridge) and Spanish collaboration maps cosmic μ-wave background at 31 GHz RFI screen (very small radio-quiet zone)

Lovell Telescope 250 ft fully steerable Upgrade in progress Consultation zone Coordination zones (per frequency band)

 Direction from the Department of the Environment to local planning authorities: 6 mile consultation zone established 10 years after telescope built  Jodrell Bank Observatory automatically consulted about any new buildings or developments, within the Consultation Zone (as part of the normal planing permission process)  Also, UK Radiocommunications Agency provides protection from certain radio transmitters anywhere in the UK (coordination to agreed levels depending on frequency band)  Direction from the Department of the Environment to local planning authorities: 6 mile consultation zone established 10 years after telescope built  Jodrell Bank Observatory automatically consulted about any new buildings or developments, within the Consultation Zone (as part of the normal planing permission process)  Also, UK Radiocommunications Agency provides protection from certain radio transmitters anywhere in the UK (coordination to agreed levels depending on frequency band) Jodrell Bank Consultation Zone

 Act to amend the code 1931 of West Virginia, passed in August 1956, enacting zoning restrictions governing the use of electrical equipment within 10 miles of any radio astronomy facility  CHAPTER 37-A. ZONING Article 1. Radio Astronomy Zoning Act  Within 2 miles it is illegal to operate any electrical equipment that causes interference  Protection within 10 miles based on field strengths of emissions (graded limits for equipment within 3,4, 5, 6, 7, 8, 9 and 10 miles)  Act to amend the code 1931 of West Virginia, passed in August 1956, enacting zoning restrictions governing the use of electrical equipment within 10 miles of any radio astronomy facility  CHAPTER 37-A. ZONING Article 1. Radio Astronomy Zoning Act  Within 2 miles it is illegal to operate any electrical equipment that causes interference  Protection within 10 miles based on field strengths of emissions (graded limits for equipment within 3,4, 5, 6, 7, 8, 9 and 10 miles) Greenbank Radio-Quiet Zone - 1

 National Radio Quiet Zone established with FCC rule making document No , Nov 1958  13,000 square miles of Virginia and West Virginia  NRAO automatically consulted about new radio transmitters within the Radio-Quiet Zone (as part of the normal licencing process)  If an ERP limit is not acceptable to the applicant, NRAO will assist in finding a mutually acceptable alternative  The laws were set up before the radio telescopes and before any frequency allocations to RAS  National Radio Quiet Zone established with FCC rule making document No , Nov 1958  13,000 square miles of Virginia and West Virginia  NRAO automatically consulted about new radio transmitters within the Radio-Quiet Zone (as part of the normal licencing process)  If an ERP limit is not acceptable to the applicant, NRAO will assist in finding a mutually acceptable alternative  The laws were set up before the radio telescopes and before any frequency allocations to RAS Greenbank Radio-Quiet Zone - 2

ALMA and mm-wave Astronomy The global situation is very good since WRC Generous allocations above 71 GHz for passive services (24% of spectrum to remain passive and a further 43% allocated to radio astronomy on primary basis). Most useable frequencies can be protected. Radio astronomy use of frequencies up to 1 THz is now officially acknowledge through Footnote S Frequency allocations above 275 GHz are on the agenda for WRC First regulatory limits on unwanted emissions from satellites. ALMA and mm-wave Astronomy The global situation is very good since WRC Generous allocations above 71 GHz for passive services (24% of spectrum to remain passive and a further 43% allocated to radio astronomy on primary basis). Most useable frequencies can be protected. Radio astronomy use of frequencies up to 1 THz is now officially acknowledge through Footnote S Frequency allocations above 275 GHz are on the agenda for WRC First regulatory limits on unwanted emissions from satellites.

 International frequency allocations for ALMA are very favourable, but need careful implementation when frequencies are assigned nationally (and regionally harmonized).  Any electrical equipment can cause interference, not just radio transmitters, so need to involve local planning authorities as well as national telecommunications authority.  ALMA Radio-Quiet Zone needs to be set up as soon as possible.  International frequency allocations for ALMA are very favourable, but need careful implementation when frequencies are assigned nationally (and regionally harmonized).  Any electrical equipment can cause interference, not just radio transmitters, so need to involve local planning authorities as well as national telecommunications authority.  ALMA Radio-Quiet Zone needs to be set up as soon as possible. ALMA Radio-Quiet Zone

Earth from Space: Forte satellite, 131 MHz

 Consortium aims to select a site by  Measurement programmes underway in China, inland Australia and elsewhere (0-2 GHz).  Investigating option to have main building and astronomers away from telescope (optical fibre connection).  OECD Task Force on Radio Astronomy is investigating ways to establish an internationally recognized radio-quiet zone, and ways to deal with satellites.  Tasso Tzioumis will say more.  Consortium aims to select a site by  Measurement programmes underway in China, inland Australia and elsewhere (0-2 GHz).  Investigating option to have main building and astronomers away from telescope (optical fibre connection).  OECD Task Force on Radio Astronomy is investigating ways to establish an internationally recognized radio-quiet zone, and ways to deal with satellites.  Tasso Tzioumis will say more. Square Kilometre Array