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研究了海事卫星BGAN系统中QPSK调制信号的盲解调技术。在没有信号先验知识的情况下,首先对QPSK信号进行了载波和码速率的精确估计,然后利用V&V算法进行初相位估计,去除载波信息;最后利用位同步估计算法,进行最佳抽取和比特判决,并针对V&V算法存在的4种相位模糊,利用BGAN的UW字段来解决模糊问题。经过比特文件的分析,证明此方法在几乎全盲的条件下盲解调有效。
The blind demodulation technique of QPSK modulated signal in marine satellite BGAN system is studied. In the absence of a priori knowledge of the signal, the QPSK signal is first accurately estimated by the carrier and code rate, and then the V / V algorithm is used to perform the initial phase estimation to remove the carrier information. Finally, the bit synchronization estimation algorithm is used to perform the best decimation and bit Decision, and the V & V algorithm for the existence of four kinds of phase ambiguity, the use of BGAN UW field to solve the fuzzy problem. After analysis of bit files, this method is proved to be effective in blind demodulation under almost blind condition.