LEO Precise Orbit Determination with Inter-satellite Links

Abstract

Traditional precise orbit determination (POD) for low Earth orbit (LEO) satellites relies on observations from ground stations and onboard receivers. Although the accuracy can reach centimeter level, there are still problems such as insufficient autonomous operation capability. The inter-satellite link (ISL) is a link used for communication between satellites and has a function of dual-way ranging. Numerous studies have shown that observational data using ISLs can be adopted for POD of navigation satellites. In this contribution, we mainly focus on LEO satellites POD with ISLs. First, we design LEO constellations with different numbers of satellites and ISL measurements, based on which the constellations are simulated. Then rough tests of POD using different link topologies are carried out. The results show that in the 60-LEO constellation the average 3-dimensional (3D) orbital errors are 0.112 m using “4-connected” link topology with constant 4 links per satellite and 0.069 m using “all-connected” link topology with theoretically maximum numbers of links. After that, we carry out refined POD experiments with several sets of satellite numbers and different observation accuracy. The results show the higher link ranging accuracy and the more numbers of links bring higher POD precision. POD with ISLs gets bad performance in the case of center of gravity reference when link ranging accuracy is poor and numbers of links are small. When the link accuracy is 40 cm, average 3D orbital errors of 60-LEO constellation are 0.358 m, which can only meet the demand of autonomous navigation. With the constraint of the right ascension of the ascending node (RAAN), POD using ISLs reaches an extremely high precision when adopting a spatial reference provided by navigation satellites. For 120-LEO constellation, the average 3D orbital errors are 0.010 m; for 192-LEO constellation, the errors are 0.006 m.

Position, Navigation, and Timing (PNT) Through Low Earth Orbit (LEO) Satellites: A Survey on Current Status, Challenges, and Opportunities

“…The authors are not aware of any commercial or open source simulators in the existing literature to simulate LEO-PNT dedicated or opportunistic signals; however, some works have recently developed their own techniques: [27], [130], [206], [207].…”

Precise Orbit Determination of LEO Satellites Based on Undifferenced GNSS Observations

“…Other information, such as intersatellite links, could be used to strengthen the model. This approach has been tested by Li et al (2019a) for different simulated LEO satellite constellations using simulated intersatellite links. The subcentimeter to decimeter accuracies achieved in this method depends on the number of links and their ranging accuracies.…”

A Survey for Recent Techniques and Algorithms of Geolocation and Target Tracking in Wireless and Satellite Systems

“…In the majority of cases, software-defined radios (SDR) with passive antennas in receiver modes are used on-board vehicles and aircrafts (UAV) to collect raw data from different LEO satellites, such as Iridium Next, Orbcomm, Globalstar and in the future, OneWeb, Starlinks, etc. [94,[155][156][157]. The goal is to identify the signal of interest (Tones) with channel frequency and develop or design an adapted receiver to track the frequency, phase and extract Doppler shift-Doppler rate for positioning and localization.…”

“…The huge potential of the present and future constellations, such as described in Table 7, demonstrate the feasibility and the reliability of these constellations when the localization and target tracking would be considered in a denied GNSS environment [94]. Until now, no open public dataset regarding LEO SoOP-based positioning systems has been released; meanwhile, considerable efforts and original results were achieved by the authors of [94,[155][156][157].…”