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Effects of RFI on radio telescopes
Effects of RFI on radio telescopes
What is radio frequency interference (RFI)?
RFI is an unwanted (normally man made) emissions that interferes with the astronomical signal received by a radio telescope
RFI includes emissions from intentional transmitters such as satellites as well as emissions from unintentional transmitters (EMI) such as computers or motors.
What is the effect of RFI on a Radio Telescope?
Depending on the strength of the RFI it can:
Cause to loss of science data (RFI > -185 dBm)
Saturate the receiver (no science possible) (RFI > -100 dBm)
Cause permanent damage to the Receive front end (RFI > +10 dBm)
RFI sources and the frequency at which they emit
RFI sources and the frequency at which they emit
RFI is caused by transmitters such as radio, TV, data links, cellular telephones or from EMI sources such as electrical and electronic equipment. For simplicity, we will refer henceforth refer to both RFI (typically narrowband) and EMI (typically wideband) sources as 'RFI'. RFI that can impact the performance (Signal to Noise - S/N - ratio) of a Radio Telescope can be caused by:
Space and Airborne transmitters (RFI):
Space and Airborne transmitters (RFI):
Navigation satellites (1.2 to 1.6 GHz band)
Communication satellites (12 GHz band)
Aircraft DME equipment (1 GHz to 1.2 GHz band)
Aircraft weather radars (10 GHz band)
Aircraft radio communications (120 MHz band)
Terrestrial transmitters (RFI):
Terrestrial transmitters (RFI):
Cellphones (900 MHz, 1 800 MHz and 2 100 MHz bands)
Television (200 MHz, 600 MHz and other)
Radio (100 MHz band)
Data links (3 GHz, 5 GHz and other)
Radio Links (450 MHz and other)
WiFi (2.4 GHz and 5.4 GHz bands).
Terrestrial Equipment (EMI):
Terrestrial Equipment (EMI):
Power lines and related equipment
Electric fences, wind and solar chargers
Domestic appliances, electronic equipment and power supply units
Computers and electronics
Telescope ancillary equipment (cooling systems etc)
Vehicles
Be careful what you do, it can cause RFI!
To see how RFI plays a role in site selection along with the required steps for maintaining a radio quiet zone, click below!
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