GNSS载波环中环路增益的自适应调节研究

Research on adaptive adjustment of loop gain in GNSS carrier loop

传统的GNSS(global navigation satellite system)软件接收机中,载波环路的环路增益是固定的,无法兼顾信号变化时的快速锁定和信号跟踪时的稳定输出2种不同需求。提出了一种基于自适应增益控制方法的载波环路设计方案,建立了一套环路增益控制模型,并给出了相应的数学定义。通过仿真分析,该方案能够有效地提升载波环路的暂态响应特性。最后通过软件接收机平台的实际验证,证明该方法能够在信号频率误差较大时实现快速锁定,当信号跟踪上后又能够提高输出信号的稳定性,从而在接收机的动态性能和噪声性能之间实现了较好的平衡。

In traditional GNSS software receiver, the loop gain of carrier loop is fixed, so quickly locking changing signal and stably generating signal in tracking can not be implemented at the same time. In this paper, a carrier loop design scheme based on adaptive gain control （AGC） is proposed; then a loop gain control model and its corre- sponding mathematical definition are given. Through simulation analysis, the design scheme can efficiently enhance the transient performance of carrier loop. At last, practical test on software receiver proves that the design scheme can quickly lock signal when the signal frequency error is large, and improve the stability of the output signal after tracking. Therefore, good balance between the dynamic performance and noise performance of the receiver can be re- alized.