radio quiet zones (rqz) - working with your national administration tasso tzioumis australia...
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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:
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