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Radio Astronomy Spectrum Management in practice – Australia (ATNF)
Tasso Tzioumis Australia Telescope National Facility 10 June 2002
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Overview Radio telescopes in Australia RFI characterisation Measured spectra Computed spectra INTER Projects SKA radio-quiet reserve 3/12/2018 Tasso Tzioumis Greenback
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Radio Telescopes in Australia
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ATCA RFI measurements April 1995, ATCA short baselines 20, 13, 5, 3 cm bands April 1997, 13 cm band 3/12/2018 Tasso Tzioumis Greenback
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20cm band April 1995 13cm band April 1995 3/12/2018 Tasso Tzioumis Greenback
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6cm band April 1995 3cm band April 1995 3/12/2018 Tasso Tzioumis Greenback
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13cm band April 1997 3/12/2018 Tasso Tzioumis Greenback
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13cm band April 1995 13cm band April 1997 3/12/2018 Tasso Tzioumis Greenback
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RFI Characterisation Predictions from ACA Database John Sarkissian, Parkes RF plots at each band, Integrated flux, RFI at each Oz telescope Includes satellite services where known 2nd and 3rd harmonics can be shown Interactive Interference Characterisation (INTER) 3/12/2018 Tasso Tzioumis Greenback
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Integrated Flux GHz 3/12/2018 Tasso Tzioumis Greenback
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RF Flux Distribution 3/12/2018 Tasso Tzioumis Greenback
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RF Transmitters near Parkes
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RFI monitoring and Mitigation
Parkes program (Mal Smith) Identify internal interference Screen observatory equipment Interference Monitoring System (IMS) Radiometer system sampler/correlator lower noise floor dBW/m^2/Hz 3/12/2018 Tasso Tzioumis Greenback
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Terrestrial Interference
Forte satellite: 131MHz 3/12/2018 Tasso Tzioumis Greenback FORTÉ satellite: MHz
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Possible SKA configuration
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SKA location Radio Quiet Reserve
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Square-Kilometre Array Australia
Luneburg Lens All sky coverage multiple simultaneous beams Possible design 5-m spheres Each patch 100 m diameter 100s of patches 3/12/2018 Tasso Tzioumis Greenback
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SKA Location WA Radio Quiet Reserve
RFI measurement system Funded by WA state government First results march-April 2001 MHz MHz Site comparison 2002 Noise floor > 30db ITU IMS under construction 3/12/2018 Tasso Tzioumis Greenback
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RFI measurement equipment
Antenna LNA SpecAn RBW = 3kHz (100Hz) Determines band • Sensitivity determined by external noise Maximum gain used • Gain ~ 40 dB 3/12/2018 Tasso Tzioumis Greenback
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IMS Modified Multibeam sampler/correlator 1024 or 2048 channel autocorrelation Sampler: 2-bit, 3-level,128Msamp/sec, IF bandwidth 64 MHz Under testing Sensitivity: For G=8dBi, at 1400 MHz, Tsys=440K, 1024ch, 64 MHz BW, 5s integ., average dBW/m^2/Hz 3/12/2018 Tasso Tzioumis Greenback
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Summary RFI characterisation at Australian telescopes Measured spectra Computed spectra – ACA database INTER – interactive characterisation Projects – monitoring and mitigation SKA radio-quiet reserve 3/12/2018 Tasso Tzioumis Greenback
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