一种基于位跳变检测的微弱卫星信号快速捕获算法

Rapid Weak Signal Acquisition Algorithm Based on Bit-flip Detection

微弱GPS卫星信号的捕获需要长的相干积分时间,同时还要克服导航数据位跳变的影响,传统算法很难同时兼顾捕获的灵敏度和实时性这两个方面。提出了一种基于位跳变检测的微弱信号快速捕获算法,该算法通过比较多组数据的相干积分结果估计出第一个跳变位,并将其余间隔20ms的数据均记为跳变位进行剔除,而对其余数据进行19ms的分块相干积分。仿真结果表明,该算法通过对140ms数据的积分运算能够高效地捕获到信噪比低至-47dB的信号,可有效提高GPS接收机的灵敏度和实时性。

For the weak GPS satellite signal, it requires longer coherent integration duration to improve the receiver Is sensitivity. Unfortunately, the influence of navigation data bit-flip limits integral duration to 20ms. It~ s difficult for the traditional methods to balance sensitivity and computation complexity. In this paper, a rapid weak signal acquisition al- gorithm based on transition detection was proposed. Firstly, the possible position of bit-flip is detected in 1ms through the comparison of the coherent integration results of the several groups of signal blocks, and the rest signal which is at intervals of 20ms with the flip bit is removed. Then coherent integration is applied to its subblock signal in 19ms and its results operate non-coherent integration to overcome its bit-flip. The theoretical analysis and simulation results show the algorithm＇s performance, and it can capture the weak signal under -47dB SNR with higher computation efficiency. The proposed algorithm will improve the sensitivity and the computation complexity of GPS receiver.