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在直接序列扩频通信中,伪码的捕获一般是通过相关运算来实现的,对于具有大多普勒频移的直接序列扩频信号,采用传统的伪码捕获方法,捕获时间将会很长,同时运算量也非常大。为了实现伪码的快速捕获,研究了一种基于FFT的伪码并行捕获算法。针对伪码长度不是2的整数次幂和存在数据跳变的问题,提出一种改善方法。计算机仿真结果表明:该方法既能满足FFT快速运算的要求又能消除数据跳变的影响,从而提高了基于FFT的伪码并行捕获性能。
In the direct sequence spread spectrum communication, the acquisition of the pseudo-code is generally realized by the correlation operation. For the direct sequence spread-spectrum signal with large Doppler shift, the traditional pseudo-code acquisition method is adopted, and the acquisition time will be very long, At the same time the amount of computation is also very large. In order to achieve fast capture of pseudo-code, a pseudo-code parallel acquisition algorithm based on FFT is studied. Aiming at the problem that the pseudo-code length is not integer power of 2 and there is data transition, an improved method is proposed. Computer simulation results show that this method can not only meet the requirements of FFT fast operation but also eliminate the influence of data transition, so as to improve the performance of parallel acquisition based on FFT.