互相关干扰下微弱GPS信号检测方法
Detection Method for Weak GPS Signal Under Cross-Correlation Effect

互相关干扰由C/A码相关特性造成，是GPS系统不可避免的问题，已成为制约接收机灵敏度的因素之一。文中提出了一种新的互相关干扰下自相关检测方法——多组数据比较法(Multi-groups data comparison,MDC)。该方法比较多组数据下捕获结果的多普勒频率和码相位，确定自相关峰的多普勒频率与码相位。对比基于均方比(Mean square ratio,MSR)和峰值相差(Peak difference,PD)检测两种方法，该方法在互相关干扰下有效提高弱信号发现概率。仿真结果表明，强信号为-124 dBm时，该方法对-145 dBm弱信号的检测概率为83%。该方法对GPS接收机弱信号捕获研究有实际意义。
Cross-correlation interference is caused by C/A code correlation properties. It is an inevitable problem for GPS systems. And it has been one of the problems affecting the sensitivity of GPS receivers. To solve the problem, a novel auto-correlation detection method based on multi-groups data comparison (MDC) is presented. In this method, the Doppler frequency and code phase within several groups of data are compared to find the auto-correlation peak. In contrast to the mean square ratio method and peak difference method, the proposed method can improve the detection probability of weak signals effectively in the presence of cross-correlation interference. The simulation results show that in the presence of one strong signal with -124　dBm power level, the method can achieve an 83% detection probability for the weak signal with -145 dBm power level. Therefore, it is useful for the acquisition of weak GPS signal.