Performance Evaluation of Data Modems for the Aeronautical Satellite Channel

Several modems and satellite subsystems were tested with the aid of an aeronautical channel simulation facility. The modems tested include a high-performance differential phase-shift keyed (DPSK) modem, a high-performance coherent phase-shift keyed (CPSK) modem, two hybrid voice-data modems, and a lower performance CPSK modem. Data performance results are presented in the form of probability of bit error versus signal-to-noise density and signal-to-multipath ratios with Doppler spread as a parameter. Some tests were conducted with a hard limiting IF processor in cascade with the channel simulator to simulate satellite characteristics. The characteristics of the aeronautical-satellite channel simulator are also described. The discussion concludes with a general evaluation of the effect of aeronautical-satellite channel characteristics on modem performance, as derived from the simulation experiments.