ARTM CPM demodulation and synchronization method with low implementation complexity

Abstract

The invention provides an ARTM CPM demodulation and synchronization method with low implementation complexity. The method comprises the following steps: firstly performing two-stage delay on a received signal to obtain three branch signals; then separately performing mixing, low-pass filtering, matching filtering and phase compensation processing on the three branch signals, performing viterbi demodulation processing on the I branch signal, then calculating a timing error and a carrier phase error by using a demodulation processing result, and finally adjusting code NCO and carrier NCO by using filtering results of the timing error and the carrier phase error to realize symbol timing synchronization and carrier phase synchronization. Compared with the existing optical demodulator, the method provided by the invention has the advantages that the error bit performance loss is smaller, the number of matching filters and the number of states necessary for demodulation are greatly reduced, the implementation complexity can be greatly reduced, and that the stability of the system can be effectively improved.

Description

technical field [0001] The invention relates to an ARTM CPM demodulation and synchronization method with low implementation complexity, belonging to the technical field of digital signal processing. Background technique [0002] In 2004, the US military ARTM wrote the Multi-h CPM modulation system into the IRIG-106 telemetry standard and named it ARTM CPM. The IRIG-106 telemetry standard stipulates that ARTM CPM is a quaternary communication, which adopts a double modulation index and is used in a cyclic transformation according to the symbol rate. The raised cosine pulse whose pulse length is 3 times the symbol period is used as the frequency pulse, which is a partial response system. [0003] The specific modulation parameters of ARTM CPM are as follows: [0004] The modulation index is {4 / 16, 5 / 16}, which changes cyclically according to the symbol rate; [0005] The symbol base number is 4, and the corresponding values ​​of the four symbols are -3, -1, 1, and 3; [00...

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Problems solved by technology

For ARTM CPM synchronization, the literature "Multi-Exponential Continuous Phase Modulation Timing and Phase Joint Estimation" uses the maximum likelihood algorithm to perform joint timing and phase estimation in the Walsh signal space, and its estimable timing deviation is small, which is only suitable for synchronization in the synchronization tracking phase

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