Research Of GPS Weak Signal Acquisition Algorithm Based On Cross-Correlation Interference Mitigation

GPS satellite navigation and positioning system has become the research hotspot in recent years because of its all-weather, real-time with high precision positioning services. Due to the presence of multipath effect, the received signal of each satellite varies from weak signal to strong signal. Besides, the inference of the strong signal to weak signal may cause the receiver’s unsuccessful acquisition. So the research of GPS weak signal acquisition has a certain practical significance. The purpose of this paper is to improve GPS receiver sensitivity for the acquisition of the weak signal.The traditional GPS weak signal acquisition algorithm eliminates the interference of noise to improve the output SNR by calculating the results of multiple related operations, which includes coherent integration algorithm and non-coherent integration. For GPS weak signal acquisition, we focus on how to eliminate the cross-correlation inference between the GPS weak signal and GPS strong signal. This thesis includes the following work: Firstly, the thesis built the hardware platform for the acquisition of actual GPS data. Secondly, this paper analyzed the cross-correlation interference mitigation algorithm. The algorithm mainly includes three steps. The part of weak signal detection is based on the mathematical modeling of the difference between first and second cross-correlation peak. The part of strong signal reconstruction is based on the tracking loop’s real-time feedback of carrier wave doppler frequency shift and code phase parameter to reconstruct GPS strong signal. The part of original strong signal minus the reconstruction of the strong signal is based on the correlation value between satellite signal and local recurrence of C/A code minus the correlation value between strong signal and the local recurrence of C/A code, after which GPS weak signal is obtained. Thirdly, by comparing the acquisition result of coherent accumulation and the superposition of coherent accumulation with cross-correlation interference elimination, we proved the effectiveness of cross-correlation interference mitigation algorithm in GPS weak signal acquisition.