一种适用于高轨空间的GNSS矢量跟踪方案设计

高轨空间中全球卫星导航系统（GNSS）信号可用性严重变差，对GNSS接收机的跟踪性能提出更高要求。利用GNSS信号传播链路模型分析了高轨空间GNSS信号特点，对比了标量跟踪和矢量跟踪这2类典型跟踪环路在高轨空间的适用性，进而设计了一种适用于高轨空间的GNSS矢量跟踪方案。该方案通过估计载噪比确定量测噪声方差阵，以对各通道量测信息进行加权处理来获得高精度的导航参数；并根据高轨航天器的动态性能确定过程噪声方差阵，利用轨道动力学模型对导航参数进行一步预测，从而实现了对各通道信号跟踪参数的准确预测及联合跟踪。仿真验证表明:所设计的跟踪方案可实现高轨空间中强信号对弱信号的辅助跟踪，从而提高了高轨空间中弱信号的跟踪性能及可用性，并对中断信号具有一定的桥接能力。 

Design of a GNSS vector tracking scheme for high-orbit space

The availability of Global Navigation Satellite System (GNSS) signal in high-orbit space deteriorates, which puts forward higher requirements for the signal tracking performance of GNSS receiver. The received power characteristics of GNSS signal in high-orbit space are analyzed by using the GNSS signal transmission link model. The applicability of two typical tracking loops, scalar-tracking and vector-tracking, in high-orbit space is compared. A GNSS vector tracking scheme for high-orbit space is designed. In this scheme, the measurement noise covariance is determined by estimating the carrier-to-noise ratio, and then the measurement information of each channel is weighted to obtain high-precision navigation parameters. The process noise covariance is determined according to the dynamic performance of the high-orbit spacecraft, and the orbit dynamic model is used to make a one-step prediction of the navigation parameters, thereby predicting the signal tracking parameters of each channel to achieve joint tracking of all channels. Simulation results show that the designed scheme can realize the assistance of strong signals to weak signals tracking in high-orbit space, so as to improve the tracking performance and availability of weak signals in high orbit space. In addition, the designed scheme also has a certain bridging ability to signal outage.