卫星回传链路CPM信号符号速率估计

解决了DVB-RCS2标准定义的连续相位调制（CPM）信号符号速率估计问题.该信号存在于卫星回传链路上,且以TDMA突发模式传输.标准规定了CPM的调制指数、调制阶数和频率成型脉冲等参数,但未对符号速率进行规定.短突发长度、低信噪比环境下实现CPM符号速率估计是信号解调的关键.文中提出了一种基于改进后的广义检测后积分（GPDI）匹配准则的符号速率估计方法.算法首先通过对信号带宽的粗估,获得信号符号速率范围;然后利用不同过采样倍数下的独特码调制波形作为特征,采用改进后的GPDI匹配准则实现信号符号速率估计.通过该方法可在单个突发帧下实现符号速率估计.仿真实验表明,该算法对频偏具有较好的鲁棒性和优异的抗噪声性能.

Symbol Rate Estimation for CPM Signals in Satellite Return Link Transmission

This paper tackles the symbol rate estimation problem of Continuous Phase Modulation （CPM） that is defined by DVB-RCS2 standard. The signal exists in satellite return link, and transmits in TDMA burst mode. The standard specifies the modulation index, modulation order and frequency shaping pulse of CPM except symbol rate. Symbol rate estimation is crucial for CPM demodulation under short burst length and low signal-to-noise ratio condition. The paper presents a method of symbol rate estimation based on improved Generalized Post Detection Integration （GPDI） match strategy. In the first stage, coarse estimation of bandwidth is used to extract the range of symbol rate. The symbol rate estimation is achieved based on the improved GPDI match strategy using the modulated unique word of different oversampling factor. The symbol rate can be estimated in one single burst frame. Simulation results show that the algorithm is robust with carrier frequency. It is able to provide good performance under low signal-to-noise ratio conditions.