Radio Quiet Zones

1. Radio Quiet Zones Tasso Tzioumis ATNF, CSIRO IUCAF IAU GA, 23 August 2006

2. Talk Outline • General RQZ introduction • RQZ History • National RQZ • International RQZ • Current initiatives – OECD, ITU • RQZ definition for SKA • RQZ(s) for proposed SKA sites • progress

3. Need for RQZ? • RA systems extremely sensitive  very susceptible to RFI • RA allocated very little spectrum (~2% at cm ) • Still RFI from out-of-band (OoB) emissions • RA operates over full radio spectrum  RFI from radiocommunication services • “prevention better than cure”  RQZ is 1st step of mitigation

4. Radio Quiet? • Radio Quiet  Radio Silent • “Passive” bands (e.g. 1400-1427 MHz) • “all emissions are prohibited” (Fn. 5.340) • but OoB emissions still a problem • RQZ  prevent “harmful” (detrimental) RFI • RFI mitigation – minimise “harm”  may influence RQZ limits & area

5. RQZ selection - Population? Sydney: population 4 million Narrabri: population 4000 Mileura: population 4

6. Where are the Quiet areas?

7. 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 • Moon & L2 point

8. 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

9. Greenbank NRQZ • The original & the best 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 • Excellent protection in practice

10. Other National RQZs • Arecibo PRCZ – Puerto Rico & islands • Coordination Zone • Jodrell Bank & other European telescopes • Mainly EMC (local) & some National coordination • GMRT • EMC – 10 km (light)30 km (heavy industry) • National coordination up to 400 km (bands) • (ALMA - Chile: 30 km RQZ, 120km coordination zone)

11. “Radio sensitive zones” in Australia • Up to now only local goodwill • Radio Act review – “radio sensitive zones” • Notification and coordination - no protection • Regulatory RALI to protect all Oz sites

12. Notification Zone Parameters • Limits derived from RA.769 (+ ~10-15 dB) • Propagation models from P.526 (Diffraction) and terrain models.

13. International RQZs • Shielded Zone of the Moon RQZ • ITU-R Rec RA.479 - Entire radio spectrum • No levels defined – coordination • But some RFIfrom spacecraft (e.g. Mars) • Prohibitively expensive • Sun-Earth Lagrangian Point L2 • ITU-R Rec RA.1417 • 1.5 million km from Earth • Excellent RQZ – WMAP (CMB) already there!

14. OECD Global Science Forum • OECD “Task Force on Radio Astronomy and the Radio Spectrum” (Report 2004) • RA and Satellite Operators • Recommendations: • Technical consultations • “Controlled Emission Zones” • ITU-R efforts • Operational consultation • Leverage for international RQZ?

15. ITU-R Question • Question in WP7D to initiate studies • Strong opposition from satellite operators • Question delicately framed i.e. • Characteristics of existing RQZ? • RAS characteristics stimulating RQZ? • environment characteristics stimulating RQZ? • Work still to be done.

16. SKA & RQZ issues

17. Square Kilometre Array • ~ 1 km2 collecting area in an interferometer array sensitivity ~50 x EVLA (current largest radio array) survey speed >10000 x faster than EVLA • wide frequency range: 0.1 – 25 GHz • configuration: longest baselines >3000 km; 50% collecting area<5km • wide field of view: 50 sq. degree at <1 GHz(250 x moon) • total cost 1 B€; operating costs 70 M€/year

18. Reference Design Inner core Station Wide-angle radio camera + radio “fish-eye lens”

19. RQZ for SKA? • SKA to operate 100 MHz – 25 GHz • Wide unprotected frequency range • Must have some RQZ protection • National efforts towards SKA RQZ(s) • All site proponents must define progress towards RQZ protection. • Protection now for SKA demonstrators • Preserve “quietness” of sites • Protect “demonstrator” and “path-finder” facilities which are in construction now. • Setup regulatory/legislative requirements for SKA in future

20. RQZ definition -SKA Regulatory “Task Force” • Report covers Protection criteria and general discussion on methodology. • Threshold levels: • “Central site” - RA.769 levels (cont & line) • Up to 150km - RA.769 Table 1 +15dB (array levels) • Remote sites - RA.769 VLBI levels • Radio propagation modelling (ITU Recs) • Complex and many assumptions

21. RA. 769 thresholds

22. Proposed SKA sites & RQZs • Argentina + Brazil (South America) • Australia + NZ • China • South Africa (+ southern Africa countries)

23. Bolivia Paraguay Chile Pacific Ocean Uruguay Atlantic Ocean

24. San Juan Barreal blanco Observatorio CASLEO

25. Core and central region CASLEO (2550m)

26. Progress towards an RQZ in Argentina • A law for RFI protection was submitted to the National Congress and is under consideration in the communications commission. • The text for the law was prepared according to the SKA requirements defining a radio quiet zone around the central site.

27. Australia + NZ

28. Progress towards an SKA RQZ in Australia • “Special” area by state law • ~ 100 x 100 kms at Mileura, WA • low prospectivity - mining restrictions (since ~2002) • License “embargo” for this area since 2005 • Special permission for any Tx, 100 MHz-26 GHz • Recent test with mining company • “Radio Astronomy Park” - 2006 (~30 km square) • SKA core site + xNTD, MWA • ACMA definition and characterisation • Restricted zone (~100 km radius) • Coordination zone (larger radius)  legislative/regulatory measures in preparation

29. Proposed SKA RQZ in Australia

30. SKA siting in China: Near remote, southwest, Guizhou, latitude 26o N, longitude 106oE Core site: typical Karst depression ~ 500 meter SKA Center Here

31. SKA remote array: 5 telescopes Miyun 50m Urumqi 25m Shanghai 25m Yunnan 40m Qinghai 14m Miyun 2600 km 1500 km 2000 km 1500 km 400km

32. RQZ area and protection: 150 km • RF requirements for RQZ area • In 80 years, RQZ 3 subsections: <1.5km, 1.5-5km, quality high, 5-150km(coordinated zone) • National and local regulationsChina radio administration regulation, legal radio stations are protected by the law. Radio waves emitted by industrial, medical, scientific, electric transportation, etc., should not interfere with those used by SKA . • Government commitment • Governments: make laws to protect RQZ areas. National Radio Regulatory Department declared to protect SKA frequencies used, control radio stations, restrict electromagnetic emission sources. Forbid the new radio stations.

33. Astronomy Reserve in South Africa • Based on reciprocal sensitivity predictions, a frequency dependent radio quiet reserve is being established in the Northern Cape, South Africa, for the protection of a future radio astronomy reserve. • The area of the defined reserve takes in account the shielding effect of topographical features. • The protection of the reserve, and other major astronomy facilities in South Africa, will be implemented through the Astronomy Geographical Advantage Act, to be tabled in parliament in Q3 of 2006. • A successful consultative process with telecom providers is underway to • Determine the impact of the reserve • Discuss various migration options to reduce current radio frequency interference (the migration of emergency and mobile communication to below 100MHz, implementation of digital broadcasting technology etc.).

34. Legislation: Astronomy Geographical Advantage Act • Empowers the Minister for Science and Technology to declare protected areas around strategic astronomy sites by publication in the Government Gazette. • The Act empowers the Minister to prohibit over-flights • The Act covers both radio and optical astronomy • Three tiers of protected areas: • Core area – the physical area of the observatory / instrument • Central area – surrounds the core area. Minister prohibits certain activities / categories of activities in this area • Coordination area –Minister sets standards which activities must comply with • Protected areas apply to existing and new activities

35. Astronomy Reserve: Central Area

36. Summary – 1 • RQZs important for RA – 1st step in mitigation • National RQZs (e.g. Greenbank) provide successful protection for telescopes • International RQZs for L2 and Moon. • OECD initiative – “controlled emission zones” • Include protection from satellites? • ITU Question on RQZ – towards IRQZs?

37. Summary –2 • RQZ for SKA – imperative! • Definition, thresholds and methodology from “Task Force” • Thresholds from RA.769 • Core & coordination zones • Remote sites - VLBI levels • Site proponents progressing work on RQZs • Legislative/regulatory measures • Protection for “demonstrator” instruments.

40. ALMA and mm-wave Protection • The global situation is very good since WRC-2000. • 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 S5.565. • Frequency allocations above 275 GHz are on the agenda for WRC-2006. • First regulatory limits on unwanted emissions from satellites (λ2/4π helps at mm-waves).

41. Cerro-Chascón Science Preserve 18 km x 19 km zone, protected against mining etc. by Chilean Government Supreme Decree No. 185, June 1998

42. ALMA Quiet Zone • Chilean telecoms authority SUBTEL already has a tradition of protecting RA at Maipú at 45 MHz (1978). • Central Quiet zone: 30 km radius, no transmitters in ALMA bands (variously 31 to 950 GHz) • 120 km radius coordination zone • AUI/ESO may comment on xmit applications • > 31 GHz, comply with 769 at site boundary • < 31 GHz, 769 + limit on transmitter power • Eirp such that pfd at ALMA border <2x10-6 W/m2 • Formal recognition is needed to avoid future changes in policy. • Need to educate the general public and politicians about radio astronomy and the need for radio quiet zone.