Satellite communication system with multiple variable data rate carrier

Abstract

Described is a satellite communication system comprising a primary station , a communication satellite and at least one secondary station . The primary station transmits data signals via the communication satellite to the secondary station . The primary station comprises a modulator for modulating the data signals onto at least two differently FEC-encoded frequency carriers. The secondary station comprises a tuner for tuning to one of the frequency carriers in dependence on a tuning signal received from the primary station . The secondary station further comprising signal quality determining means for determining at least an estimate of a signal quality of the frequency carrier presently tuned to. The secondary station comprising retuning request transmit means for transmitting a retuning request signal to the primary station when the estimate of the signal quality becomes lower than a predetermined threshold value. The primary station comprises determining means for determining a frequency carrier with a better signal quality upon reception of the retuning request signal and tuning signal transmit means for transmitting the tuning signal indicating this frequency carrier to the secondary station . In this way, when the data signals (which are modulated onto a certain frequency carrier) are received poorly (e.g. because of rain fading) the secondary station can tune to a frequency carrier with a more robust FEC-encoding and the data signals can be received without problems.