Radio Quiet Zones (RQZ)- working with your national administration

Tasso Tzioumis

Australia Telescope National Facility (ATNF)

Tasso.Tzioumis@ .csiro.au

COSPAR2008 – Montreal 14 July 2008

Why? -- 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

What? -- 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

RQZ selection - Population?

Sydney: population 4 million

Narrabri: population 4000

Mileura: population 4

Where are the Quiet areas?

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

National RQZ characteristics

• 2 distinct areas of RQZ protection1. 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

Greenbank 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

•Excellent protection in practice

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 Quiet Zone -- Chile

• 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.

“Radio sensitive zones” in Australia

• Radio Act review 2002 – “radio sensitive zones”• Notification and coordination - no protection

• Regulatory RALI (2006) to cover all Oz RA sites• Studies by ACMA (administration)

RA. 769 thresholds

Notification Zone Parameters

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

Notification Zones (km radius) Band (MHz)

Parkes Narrabri Mopra Hobart Ceduna Tidbinbilla

1 250-1 780 200 250 150 100 n/a 120

2 200-2 550 180 180 130 80 120 80

4 350-6 700 160 160 120 70 120 70

8 000-9 200 150 110 100 50 120 50

16 000-26 000 110 90 80 30 80 30

International RQZs

• Shielded Zone of the Moon RQZ• ITU-R Rec RA.479 - Entire radio spectrum• No levels defined – coordination• But some RFI from 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!

OECD Global Science Forum

• OECD “Task Force on Radio Astronomy and the Radio Spectrum” (Report 2004)

• RA and Satellite Operators

• Recommendations:1. Technical consultations2. “Controlled Emission Zones”3. ITU-R efforts4. Operational consultation

• Leverage for international RQZ?

ITU-R Question

• Question in WP7D to initiate studies• Strong opposition from satellite operators• Question delicately framed i.e.

1. Characteristics of existing RQZ?

2. RAS characteristics stimulating RQZ?

3. environment characteristics stimulating RQZ?

• Work still to be done.

Square Kilometre Array (SKA)

~ 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

Inner core

Station

SKA Reference Design

Wide-angle radio camera +

radio “fish-eye lens”

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.• Short list: Australia & South Africa

• Protection now for SKA demonstrators / pathfinders• Preserve “quiteness” of sites• e.g. Australia started with a “spectrum embargo” for 100-

150 km radius around Mileura site.

RQZ guidelines -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

South Africa Astronomy Reserve

South Africa 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

ASKA - Australia + NZ

SKA RQZ in Australia

• Studies & definition by ACMA & CSIRO• RALI MS32 - in force since 24/9/2007

Oz RQZ procedures

• From RALI MS32

Oz RQZ – EMC - 1

• EMC – RFI from unintentional transmitters• Industrial & domestic machinery

• Oz - RFI from Mining activities• Mining equipment• Communications used by mines (e.g. VHF & UHF radio)• Infrastructure for ore transport (Rail & trucks)

• Need limits and exclusion zones• Limits as per RQZ

Mineral Resource Management Area

** Work with Regional authorities **

Oz RQZ – EMC - 2

• Other RQZ RFI issues• RFI from co-located science instruments (MWA)• Self-generated RFI

• Buildings; Computers; Telescope electronics

• Must develop EMC Limits & Testing protocols• Base on MIL standards for testing• But very difficult to test to RA.769 levels

• Correlation spectrometers• Radio telescope testing (e.g. at Parkes)

• Must manage and mitigate self-RFI

Summary & lessons learned

• RQZs important for RA – 1st step in mitigation• National “RQZ”s - coordination only• Weak enforcement

• RQZ essential for SKA• Exclusion and coordination zones• Strong Enforcement• EMC controls and testing also critical

• Lesson from Oz experience:** Work closely with national communications

administration **** Work closely with Regional bodies and Governments *

• ITU Question on RQZ – towards IRQZs?• Inputs from SKA RQZ experience

Comment on the SKA RQZ in Australia in a speech by the chairman of the Australian Communications and Media Authority: