I don't remember those experiments. But it is not as complicated as it may seem. This is used routinely by satellites carrying SAR equipment.

Of course you have to start with accurate, up-to-date TLEs for the involved satellite. Then you measure the doppler curve of the received signal. You subtract the doppler curve that is caused by the passage of the satellite of your receive location, which can be calculated from the satellite TLE. The result will be the doppler curve that is caused by the passage of the satellite of the transmitter location. The combination of that doppler curve and the TLE can then be used to calculate the transmitter's geographical location.

For accurate results the frequency of the transmitter, the receiver and the satellite equipment must be very stable.

73, Nico PA0DLO

On 05-04-2023 05:30, Ashhar Farhan via AMSAT-BB wrote:

I do remember some experiments in the 1980s AMSAT newsletter of attempts at using doppler to geo-locate ground stations. Does anyone here remember those? This worked only on the linear satellites. The idea is to be able to locate emergency beacons or APRS from the emission analysis alone.

• f

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