Orbit determination for CE5T based upon GPS data

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 navigation satellites is analyzed theoretically; the received signal power and the number of satellites available in relation to the geocentric distance are studied, and the position dilution of precision is also provided. The results indicate that the positioning ability can be achieved for orbits with geocentric distance less than 60000 km, and the sensitivity of the receiver is better than -160 dBm. Additionally, both the navigation solution and pseudo-ranging are processed and analyzed, and the former is also employed to calculate the orbit. The noise level of the navigation 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. © 2016, Chinese Institute of Electronics. All right reserved.