差分GPS信号解调解码技术研究

发布时间：2018-05-30 23:22

本文选题：差分GPS + MSK　；参考：《南昌大学》2017年硕士论文

【摘要】：如今,差分GPS技术的应用变得越来越普遍。为了更好的研究差分GPS信号以便获得实时、高精度的定位结果,本文从差分GPS数据的解调算法和解码算法两个方面展开了研究。首先分析了差分GPS系统的相关技术,包括GPS系统的组成、GPS定位误差的来源和差分GPS的定位原理。并针对差分GPS数据传输协议的不同版本进行了详细比较,通过比较得出了不同版本协议之间的异同点。然后研究了差分GPS信号的解调算法。差分GPS信号的调制方式主要采用的是最小频移键控方式。本文首先对MSK信号的调制解调原理、码元同步算法和载波同步算法进行了研究,并对其中几种解调算法的性能进行了仿真比较。然后针对DFT解调算法进行优化,结果表明优化后的解调算法具有计算量小、对载波频偏和位偏移不敏感等优点。最后将该算法运用于实际差分GPS信号中,实现了对信号的正确解调。最后研究了差分GPS信号的解码算法。本文通过对协议的编码原理、奇偶校验算法以及CRC校验算法的研究,设计了针对RTCM SC-104协议的解码算法。编写C程序实现目前所有电文的完整译码过程,并通过实际数据的测试,验证了算法和程序的有效性和正确性。
[Abstract]:Nowadays, the application of differential GPS technology is becoming more and more common. In order to study the differential GPS signal better in order to obtain real time and high precision localization results, this paper studies the demodulation algorithm and decoding algorithm of differential GPS data. Firstly, the related technologies of differential GPS system are analyzed, including the composition of GPS system and the source of GPS positioning error and the positioning principle of differential GPS system. The different versions of the differential GPS data transfer protocol are compared in detail, and the similarities and differences between the different versions are obtained. Then the demodulation algorithm of differential GPS signal is studied. The modulation of differential GPS signal is mainly based on minimum frequency shift keying. In this paper, the modulation and demodulation principle of MSK signal, symbol synchronization algorithm and carrier synchronization algorithm are studied, and the performance of several demodulation algorithms are simulated and compared. Then the DFT demodulation algorithm is optimized. The results show that the optimized demodulation algorithm has the advantages of less computation and insensitivity to carrier frequency offset and bit offset. Finally, the algorithm is applied to the actual differential GPS signal to realize the correct demodulation of the signal. Finally, the decoding algorithm of differential GPS signal is studied. In this paper, the decoding algorithm for RTCM SC-104 protocol is designed by studying the encoding principle, parity check algorithm and CRC algorithm. C program is written to realize the complete decoding process of all messages at present, and the validity and correctness of the algorithm and program are verified by testing the actual data.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P228.4

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