COMETS 21-GHz advanced satellite broadcasting experiments - Evaluation of trellis-coded 8-PSK performance

An advanced satellite broadcasting system using 21 GHz has been studied by using the high-power (200 W) and wideband (120 MHz) transponders on the Com munication and Broadcasting Engineering Test Satellite (COMETS), which was launched 21 February 1998. A highly effective trellis-coded eight-Phase-Shi ft-Keying (TC8PSK) modem was developed for the COMETS satellite broadcastin g experiments, and this paper describes the degradation in the hit error pe rformance of the TC8PSK modem due to the nonlinear amplification (AM/AM dis tortion and AM/PM conversion effects), group-delay distortion, and amplitud e-frequency characteristics of the satellite transponder The results of the COMETS experiments and computer simulations indicate that the performance degradation is due primarily to the nonlinear distortion and the amplitude- frequency characteristics of the traveling wave tube amplifiers in the tran sponder.