时频域联合校正的PN码相干捕获算法

摘要

By the impact of Doppler frequency offset and unstable receiver oscillator, the received PN signal exists frequency offset and symbol synchronization.This paper presents PN sequence coherent acquisition algorithm with joint time-frequency domain correction.The joint correction of carrier frequency and symbol synchronization are based on the cyclostationary property of received PN signal, so that the corrected PN signal and local PN sequence have approximate coherency.And a longer correlation length coherent detection is achieved by the correlation characteristic function to complete the PN sequence acquisition.Simulation results show that, the PN sequence coherency acquisition has a higher detection probability at Iow SNR signal and large Doppler frequency offset.%受多普勒频偏和本地时钟漂移的影响,接收信号中存在频偏且码字不同步.针对该问题,提出一种时频域联合校正的PN码相干捕获算法.从接收信号的循环平稳特性出发,进行载波频率和码字同步的联合校正,使校正后的信号与本地PN信号具有近似相干性.基于设计的相关特征函数,实现较长相关长度下的相干检测,完成PN码捕获.仿真结果表明,该算法在低信噪比、大频偏条件下,具有较高的检测概率.