Kinematic absolute and relative orbit determination of Swarm satellites with heterogeneous orbits

Precise position information is the key to guaranteeing the successful implementation of low-earth-orbit satellite missions. The fixing of carrier phase ambiguities is important for the precise positioning and precise orbit determination of the GPS. The satellite-end hardware bias was corrected by using the observation specific bias product, and the receiver-end bias was eliminated by using the inter-satellite single difference to fix the single receiver ambiguity. Swarm satellite-borne measured data was used to carry out kinematic absolute and relative orbit determination, and the single-satellite ambiguity and double-difference ambiguity were fixed respectively to research the influence of fixing ambiguities on kinematic orbit determination accuracy. The results show that fixing ambiguities can significantly improve orbit determination accuracy. The standard deviation of the satellite laser ranging (SLR) residuals for the reduced dynamic single difference ambiguity resolution (SD-AR) orbit as a reference is better than 10 mm, which is improved by 20% compared with that of the floating solution. For kinematic absolute orbit determination, the orbit determination accuracy of the double difference ambiguity resolution (DD-AR) is improved by 26% compared with that of the floating solution, and the accuracy of the SD-AR is improved by 46%. For kinematic relative orbit determination, the baseline accuracy of the SD-AR and DD-AR of the Swarm-AC formation is improved by 40% compared with that of the floating solution. For the Swarm-AB and Swarm-BC formation satellites on heterogeneous orbits, observation data of specific periods are selected for relative orbit determination. Compared with the floating solution results, the baseline accuracy of the SD-AR is improved by 48%, and the accuracy of the DD-AR is improved by 54%. Fixing the carrier phase ambiguity in the kinematic orbit determination of low-earth-orbit satellites can significantly improve the accuracy of absolute and relative orbit determination.