常规调制信号与扩频信号的调制识别算法

由于直扩信号（Direct Sequence Spread Spectrum, DSSS）通常淹没在噪声中，为了有效地识别直扩信号、跳频信号（Frequency Hopping Spread Spectrum, FHSS）和常规调制信号，提出基于瞬时特征和高阶累积量的识别算法。首先推导证明了FM、MFSK、MPSK、DSSS、FHSS信号的归一化四阶累积量切片 是相同的，并推导得到AM和MQAM的 通用公式。然后，利用归一化四阶累积量切片 特征参数检测噪声中通信信号，利用占用带宽特征参数将信号分为扩频信号和常规调制通信信号两类；最后利用瞬时特征参数和高阶累积量特征参数，分别识别扩频信号和5种常规调制通信信号。仿真结果表明，当信噪比高于1dB时，该算法对上述7种信号的正确识别率可达到100%。 

Modulation identification algorithm for conventional modulation signals and spread spectrum signals

Since the direct sequence spread spectrum is usually submerged in noise, in order to effectively recognize the direct spread sequence signal, the frequency hopping spread spectrum and the conventional modulated signals, an identification algorithm based on instantaneous characteristics and high-order cumulants is proposed. Firstly, the normalized fourth-order cumulant slice parameters of FM、MFSK、MPSK、DSSS and FHSS are verified the same, and the general expressions of for AM and MQAM are deduced. Secondly, is used to detect the communication signals in the noise. And then the occupied bandwidth characteristic parameter is used to divide the signal into two types: spread spectrum signals and conventional modulation communication signals. Finally, the parameters of instantaneous characteristic and high-order cumulants characteristics are utilized, which identify the spread spectrum signals and the five conventional modulated communication signals, respectively. The simulation results show that when the signal-to-noise ratio is higher than 1dB, the correct recognition rate of the above seven kinds of signals can reach 100%.