Radio Quiet Zones (RQZ)

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Radio Quiet Zones(RQZ)

• Tasso Tzioumis
• ATNF, CSIRO
• RAFCAP

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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

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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

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RQZ selection - Population?
Sydney population 4 million
Narrabri population 4000
Mileura population 4
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Where are the Quiet areas?
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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
• Moon L2 point

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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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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

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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)

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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
• gt 31 GHz, comply with 769 at site boundary
• lt 31 GHz, 769 limit on transmitter power
• Eirp such that pfd at ALMA border lt2x10-6 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.

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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)

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Notification Zone Parameters

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

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Notification zone limits

• Limits derived from RA.769
• 10 dB at Parkes for 30 deg Elevation limit
• 15 dB at ATCA for array
• VLBI levels at other stations

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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!

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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?

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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.

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Square Kilometre Array

• 1 km2 collecting area in an interferometer
  array
  sensitivity 50 x EVLA (current largest radio
  array) survey
  speed gt10000 x faster than EVLA
• wide frequency range 0.1 25 GHz
• configuration
  longest baselines gt3000
  km 50 collecting arealt5km
• wide field of view 50 sq. degree at lt1 GHz
  (250 x moon)
• total cost 1 B operating costs 70 M/year
  

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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 /
  pathfinders
• Preserve quiteness of sites
• e.g. Australia started with a spectrum embargo
  for 100-150 km radius around Mileura site.

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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

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South Africa Astronomy Reserve
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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

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Australia NZ
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SKA RQZ in Australia

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

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Oz RQZ procedures

• From RALI MS32

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Summary lessons learned

• RQZs important for RA 1st step in mitigation
• National RQZs - coordination only
• Weak enforcement
• RQZ essential for SKA
• Exclusion and coordination zones
• Strong Enforcement
• Lesson from Oz experience
• Work closely with national administration
• ITU Question on RQZ towards IRQZs?
• Inputs from SKA RQZ experience

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Reference Design
Wide-angle radio camera
radio fish-eye lens
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RA. 769 thresholds