Composite Clock Algorithms for System Time in Global Navigation Satellite Systems

Schmidt, Tobias D.; Trainotti, Christian; Isoard, Jacques; Giorgi, Gabriele; Furthner, Johann; Günther, Christoph

doi:10.33012/2018.15891

Cited by 6 publications

(8 citation statements)

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“…forms a sort of lower envelope of the Allan deviations of all sources. This behavior has been observed in many simulations, also for Kepler [4]. The Greenhall algorithm computes the IEM using a Kalman filter and a renormalization of the time component of the covariance matrix.…”

Section: Synchronization and Kepler Time Scalesupporting

confidence: 55%

“…He used 24 CSL on MEO satellites, 4 CSL as well as 4 iodine clocks on LEO satellites, and one H-maser on the ground. The resulting KST is plotted in Figure 4, see Schmidt et al for more details [4]. The result shows that KST follows the H-maser for time intervals longer than 1000 seconds in the absence of measurement noise.…”

Section: Synchronization and Kepler Time Scalementioning

confidence: 89%

“…They were chosen due to the availability of data in a sufficiently large span of τ to derive two state models for them. The latter models are needed to run the composite time algorithm, which was done by Trainotti [4]. He used 24 CSL on MEO satellites, 4 CSL as well as 4 iodine clocks on LEO satellites, and one H-maser on the ground.…”

Section: Synchronization and Kepler Time Scalementioning

confidence: 99%

“…• the development of a test setup for optical inter-satellite links, described by Poliak et al [3], and • the generation of Kepler system time, discussed by Schmidt et al [4]. Additional information about the technologies used in Kepler is provided in the paper by Giorgi et al [5].…”

Section: Introductionmentioning

confidence: 99%

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Kepler � Satellite Navigation without Clocks and Ground Infrastructure

Günther¹

2018

Proceedings of the 31st International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS+ 201

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Global Navigation Satellite Systems receivers use pseudorange measurements for positioning and time determination. The control system uses the same measurements for estimating the satellite orbits, clock offsets and signal biases in a complex estimation process, which additionally involves the determination of atmospheric delays. In current systems, the separation of these different parameters imposes strong requirements on the stability of the satellite clocks and on the ground infrastructure. Several hundred ground monitoring stations are additionally used in high accuracy applications. The Kepler proposal follows a different approach. It re-uses the Galileo constellation of Medium Earth Orbiting (MEO) satellites, as well as its signals but complements them by a small constellation of Low Earth Orbiting (LEO) satellites and by selected optical Inter-Satellite Links (ISL). The LEO satellites are used to observe the signals transmitted by the MEO satellites from outside the atmosphere. The optical ISL connect all satellites in a multi-hop fashion. This enables a direct synchronization of the satellites at a level not achievable today and additionally does not require that the MEO satellites are equipped with clocks. The optical ISL furthermore provide ranges rather than pseudoranges for orbit determination as well as a broadband intra-system communication network. Terrestrial infrastructures become mostly obsolete with the Kepler approach. A single monitoring and control station remains necessary to maintain the alignment with earth-rotation, the synchronization to Universal Time Coordinate (UTC), and the capability of controlling the system.

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Section: Synchronization and Kepler Time Scalesupporting

confidence: 55%

Section: Synchronization and Kepler Time Scalementioning

confidence: 89%

Section: Synchronization and Kepler Time Scalementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Kepler � Satellite Navigation without Clocks and Ground Infrastructure

Günther¹

2018

Proceedings of the 31st International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS+ 201

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“…However, it is unobservable, since the clock states 𝒙 are not accessible. To obtain a physical realization of the IEM, a control loop is applied to a local oscillator following the scheme presented in (Schmidt et al, 2018;. It consists of a second Kalman filter which estimates the deviation of the steered clock 𝒙 ̂𝑆(𝑡) from the ideal clock, and a controller.…”

Section: Space-based Distributed Clock Ensemblementioning

confidence: 99%

Autonomous Satellite System Synchronization Schemes via Optical Two-Way Time Transfer and Distributed Composite Clock

Trainotti¹,

Dassié²,

Giorgi³

et al. 2022

ION GNSS+, the International Technical Meeting of the Satellite Division of the Institute of Navigation

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and a M.Sc. in mechatronic engineering from the University of Trento, Italy. Since 2018 he works at the Institute of Communications and Navigation at the German Aerospace Center (DLR) on precise and robust time generation for GNSS applications.Manuele Dassié holds a B.Sc in Physics from the University of Fribourg, Switzerland and a M.Sc in Aerospace Engineering from Institut Supérieur de l'Aéronautique et de l'Espace in Toulouse, France. Currently, Manuele is working on the synchronization of satellites at system level and on the implementation of a GNSS simulator, at the DLR-KN Institute.

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