高动态GPS信号粗捕和精捕算法仿真实现

Simulation realization of high dynamic GPS signal coarse acquisition and fine acquisition algorithm

为了解决高动态下对GPS信号快速捕获的问题,提出了改进的部分匹配滤波(PMF)和快速傅里叶变换(FFT)相结合的粗捕方法,对其原理和结构进行了分析,并针对其引起的扇贝损失和捕获性能不高的问题,对传统PMF+FFT方法进行加窗处理;考虑到高动态下基于扩展卡尔曼跟踪的方法对捕获后参数的精度要求很高,因此在粗捕的基础上提出了基于线性调频Z变换(CZT)算法的精捕方法,并在GPS信号理论模型和模拟高动态轨迹的基础上,实现了高动态GPS数字中频信号的生成,为进一步加快捕获速度,对于冷启动时提出了一种组合码相关的卫星快速盲搜方法;最后通过MATLAB进行系统仿真实验,验证了所提出的高动态GPS信号粗捕和精捕算法能在加速度为100 g的高动态环境下有约10 Hz的捕获精度。

For the purpose of solving GPS signal fast acquisition problem under the high dynamic, a coarse acquisition method combining improved partial matched filter （PMF） and fast Fourier transform （FFT） was proposed. The principle and structure of PMF ＋ FFT were analyzed, and windowing of traditional method was put forward for the problems of scalloping loss and low acquisition performance. Since the high dynamic tracking method based on extended Kalman filter has a high requirement for the precision of the parameter after acquisition, a fine acquisition based on Chirp-Z transform （CZT） algorithm was proposed on the basis of coarse acquisition. Based on the theory model of GPS signal and high dynamic trail, this paper has realized digital intermediate frequency GPS signal of high dynamic. In order to further speed up the acquisition, a fast blind search method of combining pseudo code correlation was adopted for cold start. Finally through the MATLAB simulation experiments, it is verified that the proposed coarse and fine acquisition algorithm for high dynamic GPS signal can achieve the acquisition dynamic performance of 100g and the accuracy of about 10 Hz in high dynamic environment.