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关于大频偏下直接序列扩频系统的码捕获,一般的处理方法是在直扩信号中引入导频信号,接收端通过对导频信号的处理进行频偏估计,并消除频偏对PN码相关值的影响(典型的有“全球星”卫星移动通信系统)。然而,依据现代军事通信低截获、低检测性的要求,这种插入导频法已不再适用于军事通信。为解决此问题,文章介绍了直接序列扩频系统的一种新型码捕获技术即利用FFT消除频偏对PN码相关值影响的串并相关捕获,并进一步深入、具体的分析了这种捕获系统的原理,研究了此种捕获算法在加性高斯白噪声信道条件下的性能。
As to the code acquisition of the direct sequence spread spectrum system at large frequency, the general processing method is to introduce the pilot signal in the DS signal, and the receiver estimates the frequency offset by processing the pilot signal and cancels the offset of the PN code The impact of correlation values (typically “Globalstar” satellite mobile communication system). However, based on the low interception and low detectability requirements of modern military communications, this insertion pilot method is no longer suitable for military communications. In order to solve this problem, this paper introduces a new code acquisition technique of direct sequence spread spectrum (DSSS) system, namely, the serial-and-correlated capture of the effects of frequency offset on the correlation of PN codes by using FFT, and further analyzes this capture system The principle of this kind of acquisition algorithm is studied under additive Gaussian white noise channel condition.