一种基于循环相关函数的双级伪码快捕方案

Performance analysis of fast PN acquisition using cyclostationarycorrelation function in the multiplex system

基于"匹配滤波+序列估计"模式的双级伪码快速捕获方案较其他方案有运算量小且与序列长度呈线形关系的优点,但是这种伪码快捕方案抗高斯白噪声能力较弱.提出了一种改进的伪码快速捕获方案,即用循环相关函数代替普通相关函数作为"序列估计"的判决函数,利用高斯白噪声、直扩信号不同的循环相关特性提升系统的抗高斯白噪声能力.通过软件仿真,证明了该系统在保证快速捕获特性的同时,可提升抗高斯白噪声能力,可获得5～6dB的处理增益.

The fast PN sequence acquisition approach based on the two series'match filter + sequence estimation' models has many advantages. It has low algorithm complexity which is linear with the length of sequence.However,this approach is weak in AWGN suppression. An improved PN sequence acquisition approach was given. Instead of other general correlation function, cyclic correlation function was employed as 'sequence estimation function'. AWGN suppression of the system was improved using the difference of the cyclic correlation between AWGN and DS signal. The simulation result shows that this system can improve AWGN suppression and obtain 5～6?dB processing gain, without loss of any good characteristics in fast acquisition.