高动态直扩信号快捕设计与FPGA实现

Fast Acquisition of High Dynamic DSSS Signals: Design and FPGA Implementation

为了解决高动态直扩信号捕获速度与资源消耗的矛盾,分析了部分匹配滤波结合快速傅里叶变换(PMF-FFT)的捕获性能。针对PMF-FFT捕获范围有限且占用硬件资源过多的问题,采用递归折叠匹配滤波器代替常规匹配滤波器的方法大大节省了硬件资源,并行FFT保证了其捕获速度,同时采用扫频方法成倍增加了频偏捕获范围。给出了该方法的FPGA设计结构与实现结果,验证了该方法的有效性。与FFT循环卷积方法相比,在频偏捕获范围一定的前提下,所提方法捕获速度快,占用资源较少,非常适合高动态直扩信号的快速捕获。

To solve contradictions between acquisition speed and resource consumption of high dynamic di-rect-sequence spread spectrum（ DSSS） signals,this paper analyzes the performance of PMF-FFT（ Part of the Matched Filtering combined with Fast Fourier Transform） method. For the disadvantage that this meth-od has limited scope of frequency acquisition and high hardware resource consumption,this paper replaces conventional matched filter by recursive and folded matched filter,resulting in saving hardware resources largely. Parallel FFT is used for ensuring the speed of acquisition. Frequency sweeping to extend scope of the frequency deviation is adopoted. The structure and FPGA implementation are discussed and the result proves the effectiveness of the proposed method. Compared with the FFT circular convolution method in certain capture range offset,the proposed method has faster acquisition speed,less resource consumption, which is well-suited for fast acquisition of high dynamic DSSS signals.