针对航天测控系统中CCSDS推荐的连续相位调制(Continuous phase modulation,CPM)信号载波相位难以恢复的问题,文中提出了一种简化非相干检测算法.首先依据最大似然比准则,推导出信号的最优非相干检测算法,然后将基于Laurent分解的CPM信号的线性模型引入,简化非相干接收机结构.同时考虑到信号相位间的连续性,每次分支度量通过处理多个符号时间的接收信号来提高检测性能.简化的接收机由几个前端滤波器和紧随其后的维特比运算部件构成,文中最后给出了L=4的高斯最小频移键控(Guassian minimum shift keying,GMSK)信号的接收性能,结果表明在误码率同为1×10-4的条件下,观察窗口为8个码元长度时,简化非相干检测比起最优相干检测算法只有1.2 dB的性能损失.%A method for simplified non-coherent detection of continuous phase modulation (CPM) signals recommended by consultative committee for space data systems (CCSDS) in aerospace telemetry, tracking and command (TT&C) system is proposed due to the difficulty in carried phase recovery. Firstly, an optimal non-coherent metric for CPM is derived from the maximum-likelihood principle. Based on Laurent decomposition, the linear expressions of CPM signals are then applied to reduce the complexity of the non-coherent receiver. In consideration of phase continuity, multi-symbol intervals of received signals are considered in every branch metric to improve the performance of the detection. Constructed with few matched filters in the front-end, the simplified receiver uses the Viterbi algorithm to perform the sequence estimation. Simulation results for the simplified non-coherent detection of guassian minimum shift keying (GMSK) signals with L = 4 are given in the end. It is shown that when the observation interval is 8 bits long, the simplified detector has only around 1. 2 dB SNR to obtain the same BER of 1×10-4 as the coherent detector.
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