A new signal fault detection algorithm for vector tracking loop in strong noise environments

强噪声下的矢量跟踪信号故障检测算法

School of Automation, Northwestern Polytechnical University, Xi’an 710072, China

Received: 1 June 2021

Abstract

In the vector tracking loop(VTL) of the satellite navigation system, the signal faults caused by the abnormal atmospheric disturbances or other interferences may be distorted when outputted by the discriminators, due to the nonlinearities in the discriminators. This makes the large bias faults in strong noise environments hard to detect and then the navigation solution may be contaminated. A new signal fault detection algorithm for VTL in strong noise environments is proposed in this paper to deal with this issue. Firstly, the reason and effects of distortion that occurs on discriminator output are analyzed. Then a new code discriminator is designed for signal fault detection, which owns a wider positive correlation output range about the code tracking error thus improving the detection ability for large abrupt bias faults and drift faults in strong noise environments. Later a third-degree spherical-radial cubature rule is employed to estimate the test statistic and its variance matrix. Finally, comparison trials about abrupt faults and drift faults in different noise environments illustrate that the proposed algorithm maintains reliable detection ability about abrupt faults that are larger than 0.5 chips and can detect drift faults in 25~30 dBHz strong noise environments.

摘要

在卫星导航系统的矢量跟踪结构中，由于鉴别器的非线性，异常的电离层、对流层延迟或多路径等其他干扰造成的信号故障通过鉴别器输出会产生失真，使得在强噪声环境下较大偏差的故障难以被检出，导致矢量跟踪结构的导航定位结果不准确。针对该问题，提出了一种强噪声环境下的矢量跟踪信号故障检测算法。该算法对鉴别器输出失真的原因及影响进行了分析; 为降低其影响设计了一种专用于信号故障检测的码鉴别器，它对跟踪通道中的码相位偏差具有更大的正相关响应范围，因而可以使故障检测算法对强噪声环境下的大偏差突变故障和缓变故障具有检测能力; 采用三阶球面-径向容积准则对测试统计量及其方差进行估计。不同噪声环境下的突变和缓变故障检测仿真实验表明，提出的算法能保持对0.5码片以上偏差突变故障的可靠检测。同时对强噪声环境比如25~30 dBHz环境下的缓变故障也具有一定的检测能力。