基于高轨航天器的GNSS接收机技术

GNSS receiver techniques based on high earth orbit spacecraft

全球导航卫星系统(Global Navigation Satellite System,GNSS)应用于高轨航天器时,因轨道高于导航卫星,可见星数量急剧减少,空间信号功率微弱,信号的快速捕获和跟踪十分困难。文章对高轨地球同步轨道(Geosynchronous Earth Orbit,GEO)接收技术进行了研究。以中国实践十七号卫星为研究对象,采用官方正式发布的发射天线方向图对GEO下GNSS信号特征及可用性开展研究分析,并针对高轨道航天器GNSS信号微弱的特点,采用长时间积分处理的梳状滤波方法、差分相干累加比特同步算法和基于动力学模型补偿的扩展卡尔曼滤波自主定轨算法设计GNSS接收机,并在半物理仿真平台进行了测试验证。试验结果表明:GNSS接收机捕获灵敏度优于-173dBW,跟踪灵敏度优于-175dBW,定轨位置精度优于50m,速度精度优于0.01m/s。

The visibility of Global Navigation Satellite System(GNSS)applied in high-Earth orbit altitudes dramatically reduces,while space signal power level is weak,and fast signal acquisition and tracking becomes very difficult.For GNSS receiver techniques research,GNSS signals characteristics and availability were analyzed in China′s GEO SJ-17 satellite.Antenna pattern was from the official release.And for high-Earth orbit spacecraft′s GNSS weak signals characteristics,GNSS receiver used long-time integration comb filter method to acquire,took differential coherent bit synchronization method to track and used extended Kalman filter orbit determination based on dynamics.Finally,hardware-in-the-loop tests show that GNSS receiver′s acquisition sensitivity is better than-173 dBW,tracking sensitivity is better than-175 dBW,the position accuracy of orbit determination is better than 50 m,and the velocity is better than 0.01m/s.