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提出一种不需要载波同步的调制识别方法,能够实现二进相移键控(BPSK)、正交相移键控(QPSK)和八进相移键控(8PSK)的识别。其方法是:首先对带有残余载波的基带信号进行定时抽样,计算抽样点的点积及叉积,并将点、叉积复合成一个复基带调相信号,其特点是调制阶数与原信号相同,而残余载波转换为固定相位;然后,利用这个复基带信号的四阶累积量构造分类向量进行分类。首先介绍四阶累积量的基本概念;然后给出相移键控(PSK)信号的表达形式,点叉积计算方法及其组合而成的复基带信号的形式;其次介绍识别算法;最后进行仿真分析,并考察了符号长度、定时误差及成形因子对分类性能的影响。
A modulation identification method without carrier synchronization is proposed, which can realize the identification of binary phase shift keying (BPSK), quadrature phase shift keying (QPSK) and octal phase shift keying (8PSK). The method comprises the following steps of: sampling a baseband signal with a residual carrier firstly, calculating a dot product and a cross product of the sampling points, and integrating the points and the cross products into a complex baseband phase modulated signal, wherein the modulation order is the same as the original The same signal, and the residual carrier is converted to a fixed phase; then, using the fourth-order cumulants of the complex baseband signal to construct a classification vector for classification. First of all, the basic concepts of fourth-order cumulant are introduced. Then, the expressions of PSK signals, the method of calculating the cross-point product and the complex baseband signals are given. Secondly, the recognition algorithm is introduced. Finally, Analysis and study of the symbol length, timing error and forming factor on the classification performance.