frequency/phase offset estimation in satellite DOA beamforming applications In satellite QPSK demodulation, we first estimate and remove the phase offset introduced by the channel. Then, we demodulate the baseband information bits (I &amp; Q channels).

In satellite DOA beamforming, Channel can also introduce phase / frequency offset. When we detect the desired signal from a certain direction in the frequency domain (spectrum), how could we detect this channel introduced phase / frequency offset?
Typically, you distribute a mixing oscillator to all ground stations, so that their respective phase is known and can hence be corrected upfront. Having known phase between these receiver parts typically requires a lot of RF design effort and external phase calibration.