一种改进的PMF-FFT算法及其验证

An improved PMF-FFT algorithm and its verification

针对硬件资源有限、低信噪比情况下提高PMF-FFT算法多普勒频率捕获精度的问题,提出了一种两轮搜索算法。文中分析了PMF-FFT算法的两种固有衰减,对其进行加窗处理以提高捕获增益。通过第一轮捕获得到码相位与粗频率,用同样的码相位进行第二轮频率搜索并比较两次搜索值,可在不增加FFT点数的情况下,将搜索频率精度提高一倍。理论分析和实测数据仿真表明,该算法在低信噪比情况下提高了检测概率,提高了捕获频率精度。

Aiming at the shortage of the traditional partial match filter-fast Fourier transform（ PMF-FFT）acquisition algorithm under low SNR（ signal-to-noise ratio） and limited hardware resource,a two step acquisition method is proposed. Starting from analysis the two inherent attenuation of the PMF-FFT algorithm,and add window improves the algorithm gain. Through the first round,it gets the code phase and the coarse frequency,with the same code phase for the second round and compare the results of two.The Doppler offsets accuracy is doubled without increasing the number of FFT points. The theoretical analysis and simulation results show that the proposed algorithm improves the detection probability under low SNR and the accuracy of the acquisition frequency.