Radio Quiet Zones (RQZ) History and Current Activities

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Radio Quiet Zones (RQZ) History and Current
Activities

• Tasso Tzioumis
• ATNF, CSIRO

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Need for RQZ?

• Radio Astronomy (RA) systems must be extremely
  sensitive as cosmic emissions very faint
• ? very susceptible to Interference (RFI)
• RA allocated very little spectrum (2 at cm
  bands) but operates over full radio spectrum (no
  control of cosmic emissions)
• ? RFI from radiocommunication services
• Must start as radio-quiet as possible - RQZ

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Radio Quiet?

• Radio Quiet is NOT Radio Silent
• Passive bands (e.g. 1400-1427 MHz)
• all emissions are prohibited (ITU-R Fn. 5.340)
• but Noise present e.g. Out-of-Band emissions
• Quiet means NO detrimental RFI
• RQZ ? prevent detrimental (harmful) RFI

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RQZ definition?

• Define threshold levels for detrimental RFI at
  the antenna(s)
• ITU-R defines detrimental RFI levels for RA
  bands
• Survey radio transmitters (present and planned)
• Likely RFI levels in the area
• Define distance that transmitters no longer
  affect the telescope
• line-of-sight almost always problems
• Propagation models for over-the-horizon -
  complex
• Terrain shielding other RFI mitigation

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RQZ History

• National RQZ
• Within an administration
• Sovereign rule can depart from ITU
• Regulate terrestrial services
• Little or no impact on satellite services
• International RQZ
• Special areas only

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National RQZ characteristics

• 2 distinct areas of RQZ protection
• EMC protection
• RFI from electrical/electronic equipment
• Protect to few kms (5-20) 30 for heavy
  industry
• Local/State Governments
• Coordination zone
• Coordinate with radio transmitters
• 100s of km
• Communications administration

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Green Bank NRQZ

• The original RQZ - model
• 1956 West Virginia Radio Astronomy Zoning Act
• Graded EMC restrictions to 10 miles
• 1958 NTIA FCC ? National RQZ
• 34000 sq km area
• Coordination of all Tx with RA telescope
• (Also protects Naval Research station)
• Excellent protection in practice

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Other National RQZs

• Arecibo PRCZ Puerto Rico islands (USA)
• Coordination Zone over entire island area (1996)
• European telescopes
• Mainly EMC (local) some National coordination
• Indian GMRT
• EMC 10 km (light)?30 km (heavy industry)
• National coordination up to 400 km (bands)
• Also protection zones around other sensitive
  antennas and laboratories.
• Mainly EMC protection

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International RQZs

• Shielded Zone of the Moon RQZ
• Entire radio spectrum - back-side of Moon
• No levels defined coordination
• But some RFI from spacecraft (e.g. Mars)
• Prohibitively expensive
• Sun-Earth Lagrangian Point L2
• 1.5 million km from Earth away from Sun
• Excellent RQZ WMAP (CMB) already there!
• Space missions necessary

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Radio Sensitive Zones

• Australian Productivity Commission
• Review of Radiocommunication Acts
• Report in 1992
• Recommendation radio sensitive zones
• Around existing radio telescopes
• NOT protection zones
• Notification and Consultation
• Mutually agreeable solutions
• ACA ATNF working towards implementation.

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Methodology Progress

• Survey of RQZ principles and practices worldwide
  (ACA)
• Summary of transmitter characteristics in
  Australia (ACA)
• Define RFI thresholds at telescopes (ACAATNF)
• ITU-R Recommendations
• Telescope characteristics
• Thresholds Propagation models ? possible radio
  sensitive zones
• Parkes and Narrabri area maps (150 km)
• Next step Appropriate regulatory implementation

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OECD Global Science Forum

• OECD Task Force on Radio Astronomy and the Radio
  Spectrum (Report 2004)
• Radio Astronomy and Satellite Operators
• Recommendations
• Technical consultations
• Controlled Emission Zones
• ITU-R efforts
• Operational consultation
• Towards international RQZ?

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RQZ for SKA?

• SKA to operate 100 MHz 25 GHz
• Wide unprotected frequency range
• Must have some RQZ protection
• RFI thresholds defined at SKA2004
• National efforts towards SKA RQZ(s)
• Australia PMSEIC - RQZ in WA?
• South African efforts SKA Act?
• SKA site selection criteria
• Include need for RQZ
• Government support critical

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Summary

• RQZs important for Radio Astronomy
• Quiet ? Silent no detrimental RFI
• National RQZs (e.g. Green Bank) provide
  successful protection for telescopes
• International RQZs for L2 and Moon.
• Australian radio sensitive zones
• Methodology applicable to RQZ
• OECD initiative controlled emission zones
• SKA RQZ critical siting criterion