高动态北斗B1I信号的快速捕获算法研究

高动态环境下,用户接收机接收到的卫星信号存在较大的多普勒频移,而实现定位导航和授时等功能对捕获算法提出了更高的要求.由于传统的时域串行捕获算法与基于FFT的并行码相位捕获算法存在时间复杂度高而造成捕获较慢的问题,本文采用改进的PMF-FFT捕获算法.捕获信号时,取2 ms输入信号与本地载波信号进行模二加后通过64个部分匹配滤波器,再将输出的数据加海明窗函数,然后进行64点FFT运算,最后将结果取模后与门限值比较,高于门限值判断捕获成功.通过实验仿真验证,该方法可以准确地完成高动态北斗B1I信号的快速捕获.

Research on Fast Acquisition Algorithm of High Dynamic Beidou B1I Signal

In a highly dynamic environment,the satellite signal received by the receiver has a large doppler shift.The realization of positioning,navigation,timing and other functions puts forward higher requirements for the acquisition algorithm.The paper uses an improved PMF-FFT acquisition algorithm,as the traditional time-domain serial acquisition algorithm and the FFT-based parallel code phase acquisition algorithms have high time complexity,resulting in slower acquiring speed.While the receiver captures the signal,the 2 ms input signal and the local carrier signal are added in the way of xorring to 64 partially matched filters,and the output data is added with hamming window function to perform 64-point FFT operation.After taking the modulo of the result,it is compared with the threshold value,and the acquisition is judged to be successful if it is higher than the threshold value.The experimental simulation results show that the method can complete the rapid capture of the highly dynamic Beidou B1I signal accurately.