说明：  调制信号的识别，可以通过各种调制的功率谱不同来识别，但这种方法在小信噪比下，性能不好，通过循环功率谱来识别，仿真表明在小信噪比下有很好的性能
(Identification of modulated signals can be modulated through a variety of different power spectrum to identify, but this method under low SNR, the performance is not good, through the cycle of the power spectrum to identify, the simulation shows that the small SNR good Performance)