Modem Simulations for Possible Use in Space Station

Abstract

Two candidate modem structures for use in the Space Station Multiple Access Communications System were simulated using a software simulation package to obtain symbol error rate curves. These systems represent an evolutionary QPSK through 8-PSK modulation format for the input data streams. It was found through the simulations that the use of phase-staggered QPSK modems would give lower expected implementation loss than a modem based upon the Polarity Costas Loop method. However, the latter would represent a simpler hardware investment to realize the modem structure for both QPSK and 8-PSK.