基于GNSS弱信号的环月航天器定轨方法研究OA

To address the challenges of signal attenuation,side-lobe acquisition difficulty,and position dilution of precision(PDOP)degradation when GNSS signals serve spacecraft in cislunar space,this study investigates the feasibility of utilizing GNSS weak signals for positioning,navigation,and timing(PNT)of lunar-orbiting spacecraft.Antenna characteristic calibration is conducted based on in-flight weak signal experiment data from the distant retrograde orbit(DRO)satellite DRO-B of the Chinese Academy of Sciences.A multi-GNSS simulation platform is developed,and a hardware-in-the-loop system is established using the DRO-B backup receiver and the Spirent GSS9000 simulator.Receiver performance under different tracking sensitivities is evaluated,followed by geometric positioning and dynamic orbit determination analyses.Results indicate that with the receiver sensitivity of-176 dBW,GNSS weak signals could effectively support spacecraft positioning and orbit determination during the Earth-Moon transfer phase within 130 000 km,with a geometric positioning error at 100 m level.During the lunar orbiting phase,the receiver sensitivity must be further enhanced to-190 dBW to meet requirements,achieving a geometric positioning accuracy of 1.67-4.04 km(three-axis)and a orbit determination accuracy of 0.02-0.06 km(three-axis)after convergence.Spaceborne GNSS could be an effective supplement to ground-based orbit determination techniques.Stable positioning and timing using multi-GNSS near the Moon is applicable in the future by further improving acquisition and tracking sensitivity and integrating multi-source measurements.