高码率导航电文引起的跟踪环路失锁及其解决方法

卫星信号的多普勒频移会引起导航数据跳变点在1ms中频采样数据中的相对位置发生滑动，当跳变点处于采样数据段的中间位置时，相关器输出接近于零，造成环路失锁。本文在详细分析这一问题的基础上，针对“北斗II”信号提出了一种改进的环路跟踪方法。新方法通过在连续的两段1ms数据中找出不包含数据位跳变点的数据段，将该段数据的鉴相结果用于2ms环路更新。仿真和GNSS模拟器的实验验证了该方法的有效性。

Lock-loss of Tracking Loop Caused by High Chipping Rate Navigation Message and Its Solution

Doppler Effect causes navigation message data bit transition boundary slip in a 1ms intermediate frequency sampling data. When the boundary appears in the middle of a sampling data segment, the output of the correlator will nearly be zero, which causes tracking loops lose lock. On the basis of analyzing this problem, the paper presents an improved tacking loop. The proposed method first locates the one without data transition in consecutive two 1ms data segments, then calculates the phase-discriminator result and uses it to replace the one obtained by 1ms data segment covering data transition to update the tacking loop. Simulation and the experiment with GNSS simulator validates the proposed method.