扩频系统中伪码防错锁技术研究

针对扩频系统中出现的伪码错锁问题,分析了产生伪码错锁的原因,根据伪码自相关性和互相关性特点,从伪码捕获策略、错锁自动判决策略等角度研究了伪码防错锁措施：选择自相关性和互相关性尽可能好的码;合理设置捕获门限;减小多普勒捕获范围;采用并行伪码捕获方法,并在捕获过程中防止载波错捕现象发生;单独建立验证通道,进行相关值比较判决等。实践表明,采用文中方法可提高正确捕获概率,缩短捕获时间,从硬件设计上有效解决了伪码错锁问题。

Prevention of PN Improper Locking Based on Spread Spectrum Systems

The cause of improper PN locking in spread spectrum system is analyzed.Based on the autocorrelation and correlation properties of PN codes,measures to prevent improper PN locking are studied from perspectives of PN code capture strategies and automatic judgment of improper locking.The measures include: choose PN codes with the best possible autocorrelation and correlation performance;set an optimized capture threshold;minimize the Doppler acquisition range;use parallel PN code capture method and prevent wrong carrier capture during acquisition;set up an independent verification channel and perform comparison and judgment of the correlation value.The application shows that the proposed methods increase acquistion probability,shorten capture time and successfully slove the problem of PN improper locking through hardware design.