Abstract
Computer simulation is used to compare the performance of several modulation formats for digital communications for mobile satellite channels. The simulation accounts for such variables as transmit and receive filtering, travelling wave tube non-linearity and uplink noise. A two-ray channel model is used to represent multiple path fading, with the relative phase of the reflected ray is assumed to be uniformly distributed. It is particularly shown that the average probability of error can be estimated from the worst case probability of error, which is much simpler to obtain. It is concluded that BPSK is the best choice over the mobile satellite channel if bandwidth is not at a premium. For bandlimited channels OQPSK and MSK provide the best performance.