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Relativistic Modelling for Highly Precise Ranging and Time Transfer via Optical Inter-Satellite Links

Dassie, Manuele (2021) Relativistic Modelling for Highly Precise Ranging and Time Transfer via Optical Inter-Satellite Links. 17th PEGASUS Student Conference, 12-16 Apr 2021, Pisa, Italy.

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Official URL: https://www.pegasus-europe.org/pegasus-student-conference/

Abstract

The DLR Institute for Communication and Navigation is currently working on a system architecture that enables accurate autonomous inter-satellite synchronization at picosecond-level via time transfer techniques enabled by optical inter-satellite links (OISLs). This paves the way for a system in which space (orbits) and time (synchronization) can be effectively separated, leading to a high level of synchronization throughout the constellation, which in turn greatly improves accurate orbit determination. This is possible provided that relativistic effects are adequately taken into account. This work focuses on a two-way time transfer scheme based on the exchange of time stamps via optical signals, which allows the synchronization of a constellation of GNSS satellites with respect to a defined coordinate time with picosecond-level accuracy. We analyse the impact of relativistic effects in clock offset estimation between optically linked clocks: results show that to achieve synchronization at this level of accuracy it is necessary to account for terrestrial geopotential harmonics up to the third order while the gravitational influence of additional celestial bodies can be neglected. Relativistic delays in the propagation of electromagnetic waves through spacetime are also evaluated. It is shown that for a two-way synchronization method, the Euclidean expression for the propagation of light is sufficient to achieve picosecond synchronization, provided m-level orbit determination of both satellites is available, and the hardware delays are well calibrated to the targeted accuracy. Also, we show how to practically achieve autonomous synchronization via a sequence of pair-wise synchronizations across all satellites of the constellation.

Item URL in elib:https://elib.dlr.de/142691/
Document Type:Conference or Workshop Item (Speech)
Title:Relativistic Modelling for Highly Precise Ranging and Time Transfer via Optical Inter-Satellite Links
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Dassie, ManueleManuele.Dassie (at) dlr.dehttps://orcid.org/0000-0002-1536-7505
Date:April 2021
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:time transfer; proper time rate; intersatellite links; relativistic propagation
Event Title:17th PEGASUS Student Conference
Event Location:Pisa, Italy
Event Type:international Conference
Event Dates:12-16 Apr 2021
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space System Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Space System Technology
DLR - Research theme (Project):R - ADVANTAGE - Optical Watches
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Communication and Navigation > Navigation
Deposited By: Dassie, Manuele
Deposited On:14 Jun 2021 13:38
Last Modified:14 Jun 2021 13:38

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