Galileo POD using optical inter-satellite links: A simulation study

Schlicht, Anja; Marz, Stefan; Stetter, Monika; Hugentobler, Urs; Schäfer, W.

doi:10.1016/j.asr.2020.06.028

Cited by 15 publications

(14 citation statements)

References 14 publications

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“…Second, the two-way link gives the possibility to synchronize the station and satellite clock. We did not study the influence of the clock synchronization on the orbit determination in this paper, but analyzed it in Schlicht et al (2019). The impact of the clock synchronization is small compared to the impact of the range measurements.…”

Section: Discussionmentioning

confidence: 99%

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Galileo precise orbit determination with optical two-way links (OTWL): a continuous wave laser ranging and time transfer concept

Marz

Schlicht

Hugentobler

2021

J Geod

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In this simulation study we analyze the benefit of ground-space optical two-way links (OTWL) for Galileo precise orbit determination (POD). OTWL is a concept based on continuous wave laser ranging and time transfer with modulated signals from and to ground stations. The measurements are in addition to Global Navigation Satellite System (GNSS) observations. We simulate the measurements with regard to 16 Galileo Sensor Stations. In the simulation study we assume that the whole Galileo satellite constellation is equipped with terminals for OTWL. Using OTWL together with Galileo L-band, in comparison with an orbit solution calculated with L-band-only, demonstrates the advantage of combining two ranging techniques with different influences of systematic errors. The two-way link allows a station and satellite clock synchronization. Furthermore, we compare the ground-space concept with the satellite-to-satellite counterpart known as optical two-way inter-satellite links (OISL). The advantage of OTWL is the connection between the satellite system and the solid Earth as well as the possibility to synchronize the satellite clocks and the ground station clocks. The full network, using all three observation types in combination is simulated as well. The possibility to estimate additional solar radiation pressure (SRP) parameters within these combinations is a clear benefit of these additional links. We paid great attention to simulate systematic effects of all observation techniques as realistically as possible. For L-band these are measurement noise, tropospheric delays, phase center variation of receiver and transmitter antennas, constant and variable biases as well as multipath. For optical links we simulated colored and distance-dependent noise, offsets due to the link repeatability and offsets related to the equipment calibration quality. In addition, we added a troposphere error for the OTWL measurements. We discuss the influence on the formal orbit uncertainties and the effects of the systematic errors. Restrictions due to weather conditions are addressed as well. OTWL is synergetic with the other measurement techniques like OISL and can be used for data transfer and communication, respectively.

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Section: Discussionmentioning

confidence: 99%

“…In this study, we analyze the optical two-way links (OTWL) (Schlicht et al 2019) concept which is based on the use of modulated optical links between Galileo satellites and ground stations. OTWL encompasses two-way continuous wave laser ranging and time transfer.…”

Section: Introductionmentioning

confidence: 99%

Galileo precise orbit determination with optical two-way links (OTWL): a continuous wave laser ranging and time transfer concept

Marz

Schlicht

Hugentobler

2021

J Geod

Self Cite

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“…In most of the research, ISL usually works as a two-way or dual one-way link (Li et al, 2019b;Marz et al, 2021;Michalak et al, 2021;Schlicht et al, 2020;Tang et al, 2018;Zhang et al, 2021), which means that each satellite serves as both transmitter and receiver. For this kind of link, the clock offsets between two satellites can be eliminated by transforming the observation equations of both satellites to a common epoch (Tang et al, 2018;Yang et al, 2017).…”

Section: Isl Range Observation Modelmentioning

confidence: 99%

“…The link topology of ISL also affects the accuracy of orbit determination. Different link topologies such as "4-connected", "all-connected", "ring", and "open ring" have already been investigated (Kur & Kalarus, 2021;Li et al, 2019b;Schlicht et al, 2020). The "4-connected" topology permanently connecting a satellite to two neighboring satellites in the same orbital plane and the closest satellites in each of the two neighboring orbital planes (Fig.…”

Section: Simulationmentioning

confidence: 99%

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Precise orbit determination for a large LEO constellation with inter-satellite links and the measurements from different ground networks: a simulation study

Hugentobler²,

Schlicht³

et al. 2022

Satell Navig

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Geodetic applications of Low Earth Orbit (LEO) satellites requires accurate satellite orbits. Instead of using onboard Global Navigation Satellite System observations, this contribution treats the LEO satellite constellation independently, using Inter-Satellite Links and the measurements of different ground networks. Due to geopolitical and geographical reasons, a ground station network cannot be well distributed. We compute the impact of different ground networks (i.e., global networks with different numbers of stations and regional networks in different areas and latitudes) on LEO satellite orbit determination with and without the inter-satellite links. The results are based on a simulated constellation of 90 LEO satellites. We find that the orbits determined using a high latitude network is worse than using a middle or low latitude network. This is because the high latitude network has a poorer geometry even if the availability of satellite measurements is higher than for the other two cases. Also, adding more stations in a regional network shows almost no improvements on the satellite orbits if the number of stations is more than 16. With the help of ISL observations, however, the satellite orbits determined with a small regional network can reach the same accuracy as that with the global network of 60 stations. Furthermore, satellite biases can be well estimated (less than 0.6 mm) and have nearly no impact on satellite orbits. It does thus not matter if they are not physically calibrated for estimating precise orbits.

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