COMBINATION OF TWO SIGNALS, THE SECOND APPEARING AS A NOISE FOR THE FIRST ONE

摘要

Users in a satellite communications network transmit signals to and receive signals from a satellite (2). In order to transmit a plurality of signals within the constraints of the available communications channel bandwidth, a first signal is combined with a second signal by introducing modifications into the second signal at predetermined intervals. The combining of signals may be carried out at the transmitter or at the satellite (2). For the purpose of separating out the second signal, the modifications are treated as errors due to noise and corrected when the combined signal is passed through a decoder (29, 75). For the purpose of separating out the first signal, the timing of the modifications is identified and the values of the combined signal at such times are determined.