Multilevel PSK Modems for TDMA System

The design and performance of 4- and 8-level Modems for a time division multiple access system are discussed, with particular attention given to the design of the filter, carrier recovery circuit, and symbol timing recovery circuit. A linear transmission model is assumed, and the designs are evaluated by the IF-BACK-BACK-BER performance. The BER performance in the 4-level Modem under nonlinear transmission is examined. In this case there is a wide disparity in the performance in a 7 stage PN and 23 stage PN sequence. Recommendations are made for improving the computer simulation method for the case of nonlinear transmission.