Research Of The Constant Envelope Signals Detection Algorithm Of The Long Distance Communication

Because the constant envelope signals have the property of constant envelope and high spectrum efficiency, they have been applied widely to the deep-space communication, the remote sensing and the telemetry. Continuous Phase Modulation (CPM) is one of the most important constant envelope signals. In this thesis, the maximum-likelihood sequence detection (MLSD) and sequential decoding detection of CPM are analyzed. Based on the decomposition of CPM, one improved sequential decoding detection algorithm is proposed, which reduces the complexity of the detection effectively.Firstly, different kinds of decomposition functions of CPM signal are researched, which are divided into linear and nonlinear forms. Based on theses equivalent decomposition, MLSD of CPM is analyzed. Further, the performances of these decompositions on the complexity reduction of detection algorithm are compared.Secondly, the sequential decoding algorithm is applied to the CPM detection in this paper. The performances and complexities of several common sequential decoding algorithms are analyzed and investigated, and then the Fano metric of CPM signal of the sequential decoding detection is deduced. During the review of Green decomposition, the law that different branches in the trellis share the same waveforms is noticed, then derived and summarized in detail. Based on this law, an improved sequential decoding detecting algorithm is proposed, which can reduce the complexity of the detection significantly. Finally, the performances of different CPM detection algorithms are simulated, including the MLSD, sequential decoding detection and the improved sequential decoding detection. The result suggests that the improved sequential decoding detection can reduced the complexity of CPM detection effectively without significant performance degeneration.The improved sequential decoding detecting algorithm of CPM proposed in this thesis can reduce the complexity of detection significantly without obvious performance degeneration. This result would be of certain reference value for the research and implementation of the constant envelope signals of the deep space communication.