一种高动态环境下卫星扩频信号的快速捕获方法研究

现代卫星导航及测控应用对接收机在高动态环境下实现测量通信提出了迫切需求。为了解决大多普勒频偏扩频信号的快速捕获问题，提出了一种在频域并行搜索码相位及多普勒频偏的双频域快速捕获方法。采用双块补零算法将长的相关积分操作分割为多个短的相关积分操作，然后采用快速傅里叶变换进行圆周相关，大大节约了处理时间，利用频域圆周移位与时域载波剥离等价的原理，大幅提高了频率搜索效率。与时域相关算法和单频域计算方法相比，在捕获灵敏度不变的条件下，该方法将计算量减少90%，显著提高了运算速度，适合高动态环境下扩频信号的快速捕获。该方案应用于星载接收机平台FPGA实现，测试结果表明该方案可以在0.1s内完成±500kHz频偏下扩频信号捕获。

Research on Quickly Acquisition Method About High Dynamic Satellite Navigation Signals

In the present satellite navigation applications,the global navigation satellite system（ GNSS） receiver must be able to work well at large dynamic environment. In order to capture rapidly satellite navigation signals at the large frequency deviation,this paper presents an improved Bi-Frequency domain calculation method which could parallel search code phase and Doppler shift. First,long correlation integral operation is divided into short correlation integration operation with double block zeros padding（ DBZP） algorithm,quickly searching code phase with circular correlation combined with Fast Fourier Transform（ FFT）,significantly reducing the amount of computation. Then the amount of computation is largely reduced with equivalence principle of the frequency domain circular shift and time domain carrier peeling. Compared with continuous acquisition algorithms and single frequency domain acquisition algorithm under the same acquisition sensitivity conditions,operation time reduces 90%. It is suitable for rapid acquisition of GPS signals under large deviation conditions. Experiments show that the method can capture GPS signal ±500kHz within 0. 1s.