现代电子技术

与北斗卫星融合的低轨卫星通导一体化系统能够有效提高我国卫星系统的导航定位和通信能力，但低轨卫星终端的高速运动会导致多普勒频偏较大，增加信号捕获的难度，因此，为了快速且准确地捕获通信导航一体化信号，文中以低轨卫星高动态引起的大多普勒频偏信号为研究对象，通过Matlab工具分别仿真验证了PMF⁃FFT算法结合补零法和加窗法的优化效果，优化后的结构能使捕获峰值提高64.7%。通过确定窗函数和补零个数优化传统的PMF⁃FFT捕获算法，并对FFT模块进行改进，使其具有可重构性以适应补零个数不同的情况。文中使用Verilog HDL硬件描述语言对优化后的PMF⁃FFT算法进行硬件实现，Vivado仿真波形和实验结果均证实了算法优化后的正确性和有效性，为低轨卫星捕获提供了理论支持。

The LEO (low earth orbit) satellite communication⁃navigation integrated system integrated with BDS (BeiDou navigation satellite system) can effectively improve the navigation⁃positioning and communication capabilities of China's satellite system. However, the high⁃speed motion of the LEO satellite terminal leads to greater Doppler frequency offset, which increases the difficulty of signal acquisition. In order to capture communication⁃navigation integrated signals fast and accurately, this paper takes the signals with greater Doppler frequency offset caused by high dynamics of LEO satellites as the research object, and verifies the optimization effect of PMF⁃FFT (partial matched filter⁃fast Fourier transform) algorithm combined with zero padding method and windowing method by the Matlab. The optimized structure can increase the capture peak value by 64.7%. Then the traditional PMF⁃FFT acquisition algorithm is optimized by determining the window function and the number of zero padding. The FFT module is improved to make it reconfigurable to adapt to the different number of zeros. In this paper, Verilog HDL is used to implement the optimized PMF ⁃ FFT algorithm. The correctness and effectiveness of the optimized algorithm have been confirmed by simulation waveform and experimental results from Vivado. To sum up, the proposed algorithm has more advantages in the field of UAV aerial object detection. It provides theoretical support for LEO satellite acquisition.