基于改进的PMF-FFT扩频信号快速捕获算法研究  

Research on fast acquisition algorithm of DSSS signal based on improved PMF-FFT

作　　者：倪媛媛[1,2] 胡永辉[1] 

机构地区：[1]中国科学院国家授时中心,西安710600 [2]中国科学院研究生院,北京100039

出　　处：《电子测量技术》2013年第8期33-36,40,共5页Electronic Measurement Technology

摘　　要：低轨道卫星通信系统存在较大的多普勒频偏,这会使本地伪码与接收伪码同步时的相关峰值急剧下降,从而加大GNSS接收机对伪码的捕获难度,增大系统捕获时间。因此,为实现大多普勒频偏下伪码的快速捕获,研究了通过加窗和补零改进的PMF-FFT捕获算法,并对窗函数进行了改进,以进一步减小扇贝损失。通过对FFT的输入数据加改进窗并补零的方法大大改善了扇贝损失;通过对PMF的输入数据加汉宁窗的方法减小了输出增益的衰减。最后通过理论分析和MATLAB仿真对改进算法进行了性能分析,分析结果表明,在恒虚警概率下,信号检测概率显著增大并且平均捕获时间明显减小,捕获性能明显提高。Low-orbit satellite communication system exists large Doppler frequency offset,which can cause sharp decline of correlation peak when the local pseudo-code and the received get synchronous.This makes GNSS receiver capture more difficult and capture time increased.Thus,to realize rapid capture of the pseudo-code in large Doppler frequency offset situation,the paper analyzes the PMF-FFT acquisition algorithm improved by adding window and zeros,and the window is improved to further reduce Scallop Loss.In this paper,by adding improved window and zeros to the FFT input data,the Scallop Loss is greatly improved.By adding Hanning window to the PMF input data,the output gain attenuation is reduced.In the end,the paper analyzes the performance of the improved algorithm through theoretical analysis and MATLAB simulation.The result shows that the signal detection probability is greatly increased and the average acquisition time is significantly reduced when applying CFAR.The acquisition performance is apparently improved.

关 键 词：PMF FFT 加窗 补零 输出增益 

分 类 号：TN[电子电信]