Abstract: The phase-modulation is one of the most commonly used digital modulations in modern communication systems.However，it is focal and difficult to classify and recognize the phase-modulated signal in communication reconnaissance field.Some popular algorithms can be utilized to solve it，for example，the time-frequency domain，the high order statistics and the constellation graph.However，some of those algorithms are easily affected by noise，and others are complex to compute，and both of them don’t adapt to realization.This paper proposes a new method that not only computes easily，but also recognizes correctly at a very low SNR.Using Matlab tool to emulate this method，the result shows that，the recognition ratio to subclass of PSK signals can reach more than 93% when the SNR is not less than 2 dB.

Key words: subclass of PSK, blind modulation recognition, low Signal to Noise Ratio（SNR）

摘要： 相位调制是现代通信系统中最常用的数字调制方式之一，对其准确的分类识别是通信侦察领域中的热点和难点问题。对于这一问题可以采用时频域法、高阶累积量法、星座图法等常用方法，但是这些方法或抗噪能力差，或计算量太大，不适合工程实现。提出了一种不仅计算量小，而且可以在低信噪比下正确识别相位调制信号的方法。利用Matlab工具进行仿真，仿真结果表明，在信噪比不低于2 dB的情况下，对PSK子类调制信号的识别率可以达到93%以上。

关键词: PSK子类调制信号, 调制盲识别, 低信噪比