单信道多个时频重叠的混合通信信号盲分离具有广泛的应用价值，是近年来通信信号处理研究领域的一个热点和难点，而单信道多个混叠通信信号的调制识别和信号个数的估计是实现单信道多个混叠通信信号盲分离的基础。该文通过分析数字调制信号的二阶和四阶循环累积量的循环频率特性和结构特征，提出一种基于循环频率特征的单信道混合通信信号调制识别的方法和实现算法，其主要特点是不需要已知混合信号的个数、功率、载频、符号率及定时等先验信息，对一些典型的数字调制信号(如BPSK, QPSK, OQPSK, MSK等)的随机混合，能够有效地辨识接收信号中所包含的信号个数以及每个调制信号的调制方式。利用计算机仿真实验，考察了不同条件下算法的性能，表明了其可行性和有效性。
Single-channel blind separation of several time-frequency overlapping communication signals, which has potential and wide application, is a hot and intractable point in the field of communication signal processing. The modulation type and source number are necessary for blind separation of several mixed signals received by single channel. In this paper, cycle frequencies of second-order and fourth-order cyclic cumulants of digital modulation signals are investigated. Based on the features of cycle frequencies, a novel method for modulation identification and source number estimation is proposed for single-channel mixed communication signals, and an algorithm is presented. The proposed approach does not need the prior information such as power, carrier frequency, symbol rate, time recovery and so on, and can effectively identify the source number and modulation type of each source when the signal received by single channel is a random mixture of several kinds of typical communication signals (BPSK, QPSK, OQPSK, MSK etc.). Through simulations under different conditions, the performance of the proposed algorithm is examined, and its effectiveness is also demonstrated.