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RFI measurements at the WSRT

RFI measurements at the WSRT. Hans van der Marel ASTRON RFI Mitigation workshop, Groningen, 29-31 March 2010. Introduction. Astronomical observations Local or non-local interference Spectrum monitoring station National Frequency allocation table Test observations for less known bands

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RFI measurements at the WSRT

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  1. RFI measurements at the WSRT Hans van der Marel ASTRON RFI Mitigation workshop, Groningen, 29-31 March 2010

  2. Introduction • Astronomical observations • Local or non-local interference • Spectrum monitoring station • National Frequency allocation table • Test observations for less known bands • Investigations for local interference

  3. Astronomical observations

  4. Astronomical observations (2)

  5. Spectrum monitoring station • Current station operational since 2005 • Latest antenna modification December 2007 • Continuous coverage 20 - 3000 MHz • Scanning 24/7 • Calibrated data • Data in RMDF format • Analysis program available • Data available to CRAF

  6. Set-up of Monitor Station R&S HF902 R&S HK309 Roof of construction hall Construction hall coax Antenna switch coax Control cable coax converter R&S EB200 receiver coax UTP Field Main building Control computer Glass fiber To ASTRON network

  7. Rohde & Schwarz EB200 Miniport receiver • Frequency range 10 kHz - 3 GHz • Noise floor -117 dBm @ 30 kHz BW • Scan speed 126 points/s 20 - 3000 MHz in 13.5 min @ 30 kHz BW

  8. HK 309 Freq range: 20 - 1300 MHz Passive Linear polarization HF 902 Freq range: 1 - 3 GHz Passive Linear Polarization (V used) Rohde & Schwarz antennae

  9. Schematic of Control Program Measurement module Measurement file measure.dat Calibration files *.dat TCP/IP connection EB 200 measurement receiver

  10. GUI of Control Program

  11. Header File (*.rmh)

  12. Schematic of Analysis Program

  13. Graphical Presentation (1)

  14. Graphical Presentation (2)

  15. Graphical Presentation (3)

  16. Test observations (e.g. 608 MHz)

  17. Investigations of local or internal interference • Usually in 1 or few telescopes • Malfunctioning equipment • E.g. oscillating amplifiers, leaking of LO • Interfering equipment • Computers, networks, lab equipment Tools: • Handheld antennas, probes, spectrum analyzer, receiver • Experience

  18. Summary • Astronomical observations are inspected,they are the most sensitive • Autoplots give first indication • Reports from astronomers • Spectrum monitoring station gives indication about possible RFI • Test observations can reveal real usability of frequency band • Good relation with National Agency is important • Know your enemy (e.g. Galileo) • Local and internal interference requires continuous attention

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