基于FFT的高动态GPS信号捕获方法优化

摘要

针对高动态环境下的GPS接收机对信号捕获速度的要求,提出一种基于小波变换和优化快速傅里叶变换(fast Fourier transform,FFT)的信号捕获方法.在基带信号预处理阶段,对采样后的中频信号进行小波变换,利用逼近信号完成码相位和多普勒频移的估计,降低基带处理信号的数据率;综合基2FFT、基4FFT和素因子算法(prime factor algorithm,PFA)的优势,对捕获过程中的大量FFT运算进行优化处理,提高运算效率.仿真结果表明,改进处理的基于FFT捕获方法可以有效地缩短捕获时间,改善基带模块性能.%According to the requirement of acquisition speed for GPS signals under high dynamic environment, a fast acquisition method applying wavelet transform and improved fast Fourier transform (FFT) is presented. In the baseband preprocessing phase. the sampling signal is processed with discrete wavelet transform,and the approximate signal is used to estimate the code phase and the Doppler frequency shift, which would greatly reduce the baseband data rate. The advantages of the radix-2 FFT, radix-4 FFT and prime factor algorithm (PFA) are considered comprehensively, and a combination algorithm is put forward to process FFT caused in the signal acquisition phase, which would improve the operational efficiency. The simulation results indicate that the improved method could significantly reduce the acquisition time and enhance the performance of the baseband module.