1. Radio Quiet Zones (RQZ) History and Current Activities Tasso Tzioumis ATNF, CSIRO

2. 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

3. 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

4. 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

5. 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

6. National RQZ characteristics 2 distinct areas of RQZ protection 1.EMC protection –RFI from electrical/electronic equipment –Protect to few kms (5-20) – 30 for heavy industry –Local/State Governments 2.Coordination zone –Coordinate with radio transmitters –100s of km –Communications administration

7. 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

9. 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

10. 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

11. “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.

12. Methodology & Progress Survey of RQZ principles and practices worldwide (ACA) Summary of transmitter characteristics in Australia (ACA) Define RFI thresholds at telescopes (ACA&ATNF) –ITU-R Recommendations –Telescope characteristics Thresholds + Propagation models  possible “radio sensitive zones” –Parkes and Narrabri area maps (150 km) Next step: Appropriate regulatory implementation

15. OECD Global Science Forum OECD “Task Force on Radio Astronomy and the Radio Spectrum” (Report 2004) –Radio Astronomy and Satellite Operators Recommendations: 1.Technical consultations 2. “Controlled Emission Zones” 3.ITU-R efforts 4.Operational consultation Towards international RQZ?

16. 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

17. 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