Research And Implementation On Synchronization Algorithms For CPM Signal Receivers

With the increasing complexity of the new space launch vehicle missions,and the increasing variety and number of sensors on the spacecraft,the amount of data for telemetry data is increasing.The traditional PCM/FM telemetry system due to its limitations of spectral efficiency and power efficiency,has already no longer meet the needs of the development of the modern aerospace telemetry.The continuous phase modulation?CPM?with high efficiency spectrum and power efficiency,is the main signal structure of the new generation telemetry system.The CPM signal demodulation usually adopts coherent mode,however,coherent demodulation is sensitive to CPM signal synchronization error,resulting in higher requirements on synchronization algorithm.At the same time,the state of the CPM signal is more,which also leads to higher complexity of the synchronization algorithm.In response to the above problems,the researches on the low complexity synchronization technology of CPM signals are impletmented in the dissertation.The specific work is as follows:?1?The basic principle of CPM signal modulation is studied.The phase transition relationship between single modulation index CPM and multi-modulation index CPM is analyzed.The optimal demodulation algorithm of CPM signal is studied.The pulse amplitude modulation?PAM?decomposition and maximum likelihood sequence detection?MLSD?demodulation algorithm for multi-modulation index CPM signals are studied.The TMNSMessage frame structure of the telemetry network system information in the IRIG standard is also studied.?2?For the MLSD early-late loop timing synchronization algorithm,there are some problems due to the large number of matching filters and grid states.Based on frequency pulse truncated?FPT?and PAM decomposition,a joint synchronization algorithm named as FPT-PAM symbol Synchronization algorithm is proposed.Which performs PAM decomposition on the CPM signal based on the frequency pulse truncation.The detector after this state reduction is used for symbol synchronization,which greatly reduces the complexity of the symbol synchronization algorithm.The complexity analysis and simulation results show that the total mesh state number and matched filter of the proposed algorithm are 1/8 of the MSLD algorithm,with the performance loss only 1 dB worse than the MSLD algorithm at the bit error rate10^-5.Therefore,the proposed algorithm can significantly reduce the complexity,with very low performance loss.?3?Based on the analysis of the influence of carrier frequency offset and phase deviation on the demodulation performance of CPM signals,the carrier frequency synchronization and phase synchronization algorithms suitable for CPM signals are studied.The carrier phase synchronization algorithm based on PAM decomposition is proposed.Where the PAM decomposition uses PAM pulses dominated by waveform energy are employed to estimate the phase,and the complexity is reduced.It is close to the theoretical modified Cramer-Merro boundary at high SNR,and the performance loss is only 1dB worse than the MCRB boundary at the phase estimation variance10^-4.?4?The implementation scheme of the CPM signal receiver synchronization algorithm is designed and verified on the FPGA hardware platform.The specific design content includes the configuration of AD9361 chip,the early and late tributary module based on Viterbi decoding,the timing error estimation module,and the complex multiplier and frequency offset error estimation module.The feasibility of the CPM signal synchronization algorithm and the correctness of the synchronization module are verified by the functional test of symbol timing synchronization and carrier frequency offset synchronization module.