精度改进的B1频点快速捕获算法及FPGA实现

Accuracy-improved B1 signal fast acquisition algorithm and FPGA implementation

北斗静止轨道卫星电文传输速率高,电文翻转导致捕获算法的相关增益和频移搜索精度降低。针对这一问题,结合传统部分匹配滤波器与FFT捕获算法的优点,提出一种能够消除导航电文翻转提高频移搜索精度的快速捕获方法。首先给出算法的理论论证;然后将算法的有效性同传统算法比较;最后对算法的工程实用性通过FPGA平台进一步验证。算法仿真以及FPGA平台的测试结果表明,在获得相同伪码搜索精度的条件下,该方法能够消除电文翻转对多普勒频移搜索精度的影响,实现北斗B1信号的高精度快速捕获。

The high message transmission rate ofGEO （geostationary orbit satellites） for BDS may lead to reduced correlation gain and searching precision of frequency shift in acquisition algorithm. In order to solve this problem, combining with the advantage of traditional partial matched filter and FFT acquisition algorithm, a fast acquisition method which can eliminate transition of navigation message and improve the searching accuracy of frequency shift is proposed. Firstly, theoretical demonstration of the algorithm is given; the algorithm validity is then compared with traditional algorithm＇s; finally, the engineering practicability of the algorithm is further verified through FPGA platform. Results of algorithm simulation and FPGA platform test show that in the same condition of pseudo code searching precision, the current method can eliminate transition influence of navigation message on the searching accuracy of doppler shift, and fast capture ability of B 1 signal is achieved with high precision under the condition of same searching precision of pseudo code.