Radio Astronomy Spectrum Management in practice Australia ATNF

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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

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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

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20cm band April 1995
13cm band April 1995
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6cm band April 1995
3cm band April 1995
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13cm band April 1997
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13cm band April 1995
13cm band April 1997
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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)
• www.parkes.atnf.csiro.au

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Integrated Flux 0.1-10 GHz
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RF Flux Distribution
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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 ? -234.7 dBW/m2/Hz

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Terrestrial Interference

• Forte satellite 131MHz

FORTÉ satellite 131 MHz
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Possible SKA configuration
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SKA locationRadio 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

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SKA LocationWA Radio Quiet Reserve

• RFI measurement system
• Funded by WA state government
• First results march-April 2001
• 30-150 MHz
• 1060-1800 MHz
• Site comparison 2002
• Noise floor gt 30db ITU
• IMS under construction

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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

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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 G8dBi, at 1400 MHz, Tsys440K,
  1024ch, 64 MHz BW, 5s integ., average 100 ?
  -234.7 dBW/m2/Hz

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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