基于广义差分相干累加的高灵敏度GPS捕获算法

High-sensitivity GPS Acquisition Method Based on Generalized Differential Coherent Integration

分析传统的非相干累加算法和差分相干累加算法的性能,针对传统捕获方法性能的不足,给出一种基于广义差分相干累加的高灵敏度GPS捕获算法。该算法采用多路差分相干累加的实现方法,不增加预相干累加时间即可达到理想的噪声压制效果,与传统算法相比具有更好的噪声压制性能。文中还分析了该算法受数据比特跳变和残留载波多普勒频移的影响。仿真结果表明,与传统算法相比,广义差分相干累加算法可以使捕获灵敏度提高3dB左右,能够在无辅助信息条件下使用400ms的采样数据捕获到强度为-150dBm的信号。

Aiming at the high-sensitivity GPS acquisition problem of conventional methods,a new acquisition method based on generalized differential coherent integration is proposed by analyzing the acquisition performance of non-coherent integration and differential coherent integration.The proposed method derives its major impetus from the multi-differential coherent integration.The adequate noise suppression is achieved without the increase of coherent integration period.The major benefit of the developed method stems from its enhanced noise suppression.The limitations of the proposed method in terms of navigation data and frequency drift are analyzed.Finally,the simulation results demonstrate that the proposed method has average 3dB superior performance than conventional methods,and can acquire signals below-150dBm for an acquisition time of 400ms without any assisted information.