Feeder link synchronization

A system to synchronize frequency and time with respect to a satellite, the system comprising:

• a beacon receiver to receive a beacon signal (fB,TXN) and to calculate a frequency offset ({circumflex over (f)}B,e) due to an instability of a satellite oscillator from the beacon signal;
• an ephemeris module to determine a Satellite Motion Doppler Correction for Ephemeris (SMDCe) of a satellite motion based on ephemeris data for the satellite;
• a sync module to compute a Satellite Reference Drift Correction for Ephemeris (SRDCe) based on the frequency offset, the beacon signal and the SMDCe;
• a loopback transmitter to set a loopback TX frequency based on the SRDCe and the SMDCe, and to transmit a loopback TX signal to the satellite at the loopback TX frequency;
• and
• a loopback receiver to receive a loopback RX signal based on the loopback TX signal, and to estimate an uplink frequency offset and a downlink frequency offset from a loopback RX signal based on the loopback TX signal,
• wherein the sync module updates a Satellite Reference Drift Correction (SRDC) as SRDC′ and a Satellite Motion Doppler Correction (SMDC) as SMDC′ using the SRDCe, the SMDCe and the downlink frequency offset, and
• the sync module adjusts traffic channel RX and TX frequencies based on SRDC′ and SMDC′.