Patent ID: 8489018

Claim:
A method for determining frequency and symbol rate corrections for transmissions in a satellite communications system, the method comprising: determining a frequency correction and a symbol rate correction for transmissions from a user terminal by: determining a frequency of a signal received at the user terminal, the signal transmitted from a gateway to the user terminal via a satellite in the satellite communications system; determining a symbol rate of the signal received at the user terminal; computing an error associated with an oscillator at an outdoor unit of the user terminal based at least in part on the frequency of the signal received at the user terminal; computing an error associated with an oscillator at an indoor unit of the user terminal based at least in part on the frequency of the signal received at the user terminal; computing a transmit frequency correction for the user terminal based at least in part on the error of the oscillator at the outdoor unit and the error of the oscillator at the indoor unit; and computing a transmit symbol rate correction for the user terminal based at least in part on the error of the oscillator at the indoor unit; determining a correction for transmissions received at the gateway by: determining a frequency of a signal received at the gateway, the signal transmitted from the user terminal to the gateway via the satellite; computing an error associated with an oscillator at the satellite and motion of the satellite based at least in part on the frequency of the signal received at the gateway, the signal transmitted from the user terminal to the gateway via the satellite; and computing a receive frequency correction for the gateway based at least in part on the error associated with the oscillator at the satellite and the motion of the satellite.