The utilization of Global Navigation Satellite System (GNSS) is becoming an attractive approach for the orbit determination of geostationary orbit (GEO) satellites. As a flight test for the feasibility of GNSS-based orbit determination at high orbit altitude, a GEO satellite named TJS-2 is launched. This satellite is equipped with a high-gain antenna, a pre-amplifier, and a high-sensitivity receiver. This study investigates the methods of high-sensitivity processing for the GNSS side lobe signals and the onboard orbit determination filter to improve navigation performance. In accordance with flight data, the GNSS signal characteristics, including availability, position dilution of precision (PDOP), carrier-to-noise ratio density (C/N₀), and quality of observations, are analyzed. The mean number of GPS, GLONASS, and BDS satellites tracked is 7.6, 4.6, and 0.3, respectively. The mean PDOP of GPS, GPS + GLONASS, and GPS + BDS satellites tracked is 10.8, 8.4, and 8.9, respectively. The distribution of C/N₀ and the number of observations with respect to the nadir angles are illustrated. For GPS, GLONASS, and BDS, the corresponding standard deviation of the pseudorange noise is 7.7, 16.1, and 5.2 m, and that of the carrier-phase noise is 37.6, 41.8, and 53.7 mm, respectively, in terms of C/N₀ < 30. We give the navigation performance through comparisons with two reference orbits. The root mean square (RMS) of position accuracy of the onboard solutions in radial, along-track, and cross-track directions is 20.90, 3.34, and 2.68 m, respectively. The RMS of position accuracy in radial direction is reduced to 4.13 m after the optimization of the orbit determination filter parameters. For the single-epoch least squares solution, the velocity accuracy can improve from 0.25 to 0.16 m/s when GPS and GLONASS observations are combined. We discuss the performance of single-epoch least squares solutions combined with BDS observations. A remarkable improvement in the vertical dilution of precision is obtained when BDS inclined geostationary orbit observation is involved. The RMS of position and velocity accuracy is reduced from 39.30 to 16.90 m and from 0.26 to 0.09 m/s, respectively.

全球导航卫星系统（GNSS）的使用正在成为地球静止轨道（GEO）卫星轨道确定的一种有吸引力的方法。作为高轨道高度基于GNSS定轨可行性的飞行试验，发射了一颗名为TJS-2的GEO卫星。这颗卫星配备了高增益天线、前置放大器和高灵敏度接收器。本研究探讨了对GNSS旁瓣信号和机载定轨滤波器的高灵敏度处理方法，以提高导航性能。根据飞行数据，GNSS信号特性，包括可用性、位置稀释精度（PDOP）、载噪比密度（C / N ₀) 和观测质量进行分析。跟踪的 GPS、GLONASS 和 BDS 卫星的平均数量分别为 7.6、4.6 和 0.3。GPS、GPS + GLONASS 和 GPS + BDS 卫星跟踪的平均 PDOP 分别为 10.8、8.4 和 8.9。说明了C / N ₀的分布和相对于天底角的观测数量。GPS、GLONASS、BDS对应的伪距噪声标准差为7.7、16.1、5.2 m，载波相位噪声的标准差分别为37.6、41.8、53.7 mm，以C / N表示₀ < 30. 我们通过与两个参考轨道的比较来给出导航性能。径向、沿航迹和跨航迹方向的车载解位置精度的均方根 (RMS) 分别为 20.90、3.34 和 2.68 m。定轨滤波器参数优化后，径向位置精度均方根值降至4.13 m。对于单历元最小二乘解，当 GPS 和 GLONASS 观测相结合时，速度精度可以从 0.25 提高到 0.16 m/s。我们讨论了结合 BDS 观测的单历元最小二乘解的性能。当涉及到北斗倾斜地球静止轨道观测时，精度的垂直稀释得到了显着改善。位置和速度精度的 RMS 从 39.30 降低到 16。