CE5T星载GPS数据的定轨分析

Orbit determination for CE5T based upon GPS data

嫦娥五号飞行试验器搭载星载多模接收机,验证星载接收机接收导航星旁瓣信号的能力,首次实现了利用旁瓣信号对大椭圆轨道航天器的导航定位。理论分析了导航星旁瓣信号接收的可行性,基于嫦娥五号飞行试验器轨道特性研究了接收机接收信号功率及可视导航星数目与地心距变化的关系,并给出了理论几何定位因子。分析表明,接收机灵敏度达到-160dBm条件下,可具备6×104 km以下高度的定位能力。对获取的导航解数据及伪距进行了处理分析,利用导航解进行定轨计算,导航解的噪声水平优于10m。利用差分伪距数据进行定轨计算,残差噪声约为8.5m,使用1h数据可以实现定轨预报1h优于百米的精度,达到地基数据长弧条件下定轨预报精度水平。

With a multiple-mode receiver onboard, Chang＇e-5 test vehicle （CE5T） was tested on its ability to receive the side-lobe weak signal of global navigation satellite system （GNSS） satellites. Results show that the on board receiver can receive the signal, and its navigation and positioning for the large elliptical orbit phase using the GNSS satellite side-lobe signal are achieved. The possibility of receiving the side lobe signal of naviga- tion satellites is analyzed theoretically; the received signal power and the number of satellites available in rela- tion to the geocentric distance are studied, and the position dilution of precision is also provided. The results in- dicate that the positioning ability can be achieved for orbits with geocentric distance less than 60 000 km, and the sensitivity of the receiver is better than -160 dBm. Additionally, both the navigation solution and pseudo-ran- ging are processed and analyzed, and the former is also employed to calculate the orbit. The noise level of the naviga- tion solution is better than 10 m. Using differential pseudo-ranging, the noise level is approximately 8.5 m. One hour long data of the differential pseudo-ranging can achieve one hour forecast orbit accuracy of better than 100 m, which will have to be obtained with long-arc data for the ground-based tracking stations.