To solve the problem of the demodulation of MFSK signal in non-cooperative communication, this paper presented a new blind demodulation algorithm for MFSK signal based on all-digital enhanced phase-lock loop where no apriori information about the signal was needed. Used a few symbols to extract symbol rate at first, and then accomplished clock synchronization, modulation level identification and symbol identification simultaneously based on the frequency tracking signal of the all-digital enhanced phase-lock loop. The input MFSK signal could be demodulated according to result given above at last. This algorithm was practical and it was easy to implement in FPGA. Simulation result shows that the accuracy rate of the demodulation of 2FSK, 4FSK and 8FSK signals is above 95% when the SNR is 4 dB.%针对非协作通信下MFSK信号解调的问题,提出一种基于全数字锁相环的无须任何先验信息的盲解调算法.该算法首先应用较少的码元提取出码元速率,随后通过对锁相环输出的频率跟踪信号进行处理,实现符号同步、符号门限和进制估计,最后依据前面的估计结果对MFSK信号进行实时解调.该算法实用性强,易于在FPGA中实现.仿真实验表明,该算法具有较好的解调性能,当输入信噪比大于4 dB时,对2FSK、4FSK和8FSK的解调正确率都可以达到95％以上.
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