正交通道中码分干扰对载波捕获的影响分析及研究

Analysis and research on influence of orthogonal code division interference on carrier acquisition

在多功能数字基带的信号处理过程中,由于正交通道的码分干扰较大,传统的FFT算法无法进行载波捕获。文中从理论上分析了正交通道中扩频码对FFT算法的影响,并进行了仿真分析,最后提出双向搜索捕获算法和增加平方算法两种方法在消除码分干扰中的应用。双向搜索捕获算法在完成码捕获的同时能获得多普勒频率;增加平方算法能有效消除码分多址的影响,精确计算多普勒频率,简单实用。实验结果表明,两种消除码分干扰的算法各有优点,在实际工程应用中可根据需要选择使用。

In signal processing of the multifunctional digital baseband,the orthogonal code division multiple access(CDMA)causes relatively severe interference,which prevents the traditional FFT(fast Fourier transform)algorithm from figuring out carrier frequency acquisition.In this paper,the influence of spreading code in orthogonal channels on FFT algorithm is analyzed theoretically and simulated.Then,two methods,named bidirectional searching capture and doing square,are proposed to eliminate the code division interference,of which,the former one obtains Doppler frequency at the same time of PN code capture,while the later one can eliminate the bad effect of CDMA effectively and acquire Doppler frequency precisely,which is simple and practical.The experimental results show that the two algorithms for eliminating code division interference have their own advantages,and they can be selected and used as needed in practical engineering applications.