大动态PCM/FM遥测信号的非相干解调

Non-coherent Demodulations for Large Dynamic PCM/FM Telemetry Signal

针对大动态低码率PCM/FM遥测信号的可靠接收问题展开研究,给出了一种基于连续相位调制(CPM)信号原理的载波频偏矫正及差分序列检测的非相干接收方案。针对限幅鉴频、多符号检测及差分序列检测等3种非相干解调算法,介绍了各自应用于PCM/FM信号的算法原理,并比较了3种算法的解调性能及对大动态环境的适应能力。计算机仿真表明,在无残留频偏情况下,2符号相位差分序列检测性能最好;但在0.05倍码速率的残留频偏下,1符号相位差分序列检测的性能更好,优于2符号相位差分序列检测、限幅鉴频检测和多符号非相干检测。对PCM/FM信号的讨论包含了几种典型的非相干解调,对大动态环境下的PCM/FM接收有重要的参考价值。

Reliable receptions for pulse-code modulation/frequency modulation （PCM/FM） telemetry sig-nal with low-bit-rate in large dynamic conditions are studied. A non-coherent scheme based on continu-ous phase modulation （CPM） principles is proposed, which includes the correction of carrier frequency offset and differential phase sequence detection by Viterbi algorithm. Principles of three types of non-co-herent demodulations for PCM/FM, i.e. limited-discriminator detection, multiple-symbol detection and differential phase sequence detection, are discussed. Their detection performances and adaptabilities to large dynamic conditions are compared as well. Computer simulations show that the sequence detection for 2-symbol phase difference performs the best when without residual Doppler frequency offset. While with a frequency offset of 0.05 times of symbol rate, the sequence detection for 1-symbol phase difference is bet-ter than that for the 2-symbol phase difference, and also better than the other two methods. The discus-sions about PCM/FM signal include three typical non-coherent demodulations, which are important refer-ences to the receptions of PCM/FM signal in large dynamic conditions.