卫星回传链路CPM信号调制识别研究

Modulation Classification for CPM Signal in Satellite Return Link Transmission

文章解决了DVB-RCS2标准中规定的卫星回传链路上连续相位调制信号(CPM)调制识别问题。根据调制参数的不同,标准中的CPM信号有5种类型,且在TDMA突发模式下传输。短突发长度和低信噪比环境下信号调制识别是实现信号正确解调的前提。提出了一种基于改进后的广义检测后积分(GPDI)匹配准则的调制识别方法。该算法采用改进后的GPDI匹配准则获得接收信号与每类CPM的匹配值;并按最大值准则估计得到信号类型从而实现信号调制识别。通过该方法可实现单个突发帧内调制识别。仿真实验表明,该算法不需符号速率的先验信息,对大频偏和相偏具有较好的鲁棒性,具有较低的复杂度和优异的抗噪声性能。

This paper tackles the problem of modulation classification for the return link of DVB- RCS2 standard with Continuous Phase Modulation（CPM） . The standard specifies five kinds of CPM according to different modulation parameters, and the signal is transmitted in TDMA burst mode. Modulation classification is a prerequisite for correct signal demodulation under short burst length and low signal-to-noise ratio condition. The paper presents a method of modulation classification based on improved Generalized Post Detection Integration（GPDI） match strategy. The algorithm u- ses the improved GPDI match strategy to get the match value of the received signal with each type of CPM, and the modulation classification is completed when the estimated signal type is achieved by using the max strategy of the five match value. The modulation classification can be estimated in one single burst frame. Simulation results show that the algorithm is robust with strong carrier frequency and phase error without the prior information of symbol rate. It is able to provide good performance under low signal-to-noise ratio condition and has low complexity.