Rfi measurements at the wsrt
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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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Rfi measurements at the wsrt

RFI measurements at the WSRT

Hans van der Marel

ASTRON

RFI Mitigation workshop, Groningen, 29-31 March 2010


Introduction

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


Astronomical observations

Astronomical observations


Astronomical observations 2

Astronomical observations (2)


Spectrum monitoring station

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


Set up of monitor station

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


Rohde schwarz eb200 miniport receiver

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


Rohde schwarz antennae

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


Schematic of control program

Schematic of Control Program

Measurement module

Measurement

file

measure.dat

Calibration

files

*.dat

TCP/IP connection

EB 200 measurement receiver


Gui of control program

GUI of Control Program


Header file rmh

Header File (*.rmh)


Schematic of analysis program

Schematic of Analysis Program


Graphical presentation 1

Graphical Presentation (1)


Graphical presentation 2

Graphical Presentation (2)


Graphical presentation 3

Graphical Presentation (3)


Test observations e g 608 mhz

Test observations (e.g. 608 MHz)


Investigations of local or internal interference

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


Summary

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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