Distance measures for viterbi decoding of coded and bandlimited 8PSK signals

Abstract

The paper studies a digital modem that transmits a convolutionally encoded eight-phase-shift keyed (CE8PSK) signal over a satellite channel and employs a near-maximum-likelihood decoder at the receiver. Several different earth-stations are assumed to have simultaneous access to a given transponder in the satellite as an arrangement of frequency-division multiple access. The paper describes the various techniques involved in the modem, and presents the results of an extensive series of computer-simulation tests to measure the performances of the system with all appropriate combinations of the signal bandwidth, demodulation process and distance measure. The results of the tests are then used to determine the preferred modem design.