Narrow-band And High-efficiency Data Transmission System Based On CPM

Continuous Phase Modulation (CPM), one kind of constant envelope modulation, can adopt cheap nonlinear amplifier. Because of its continuous phase, CPM signal has the advantages of high bandwidth utilization and high power efficiency. Since CPM baseband modulator can be considered as a coder, CPM signal has a certain coding gain. All these advantages make it used widely in fading channels and satellite communications.To improve the throughput of CPM system, this paper begins with the study of CPM system synchronization based on MSK modulation. A synchronous waveform is constructed and three kinds of synchronization strategies are proposed. Then this paper focuses on the performance of the CPM signal, develops a method for increasing the bandwidth utilization based on spectrum processing. Simplified Viterbi algorithm is proposed in order to reduce the computation and shorten modulation delay. Also given in the article are its principle, performance and computation of each algorism. Finally, it concludes with its practical value in the further use.