Delta-T: All Optical Time Tagging in Satellite Laser Ranging And Optical Delay Compensation For Very Long Baseline Interferometry Based On Ultra-Short Mode-Locked Laser
Final Report Abstract
The techniques of space geodesy have matured to the point that the terrestrial reference frame composed out of the combined measurements of Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), the Global Navigation Satellite Systems (GNSS) and the Doppler Orbitography and Radio-positioning Integrated by Satellite instrument (DORIS) is consistent to several parts per billion. However, systematic measurement errors in the instrumentation still persist and are caused by variable delays in the electronic circuitry. Utilizing an active optical delay compensating time and frequency distribution system based on mode-locked lasers, we were able to identify and capture these effects, which are of the order of up to 30 ps in some cases. This improvement comes at the expense of a considerable increased complexity of the measurement instrumentation. However, since the accuracy of the terrestrial reference frame is desired to be better than 1 part in 10^9, this effort is inevitable.
Publications
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Coherent Time and Frequency for an Improved Global Geodetic Observing System.
Schreiber, Karl Ulrich; Kodet, Jan; Klügel, Thomas & Schüler, Torben
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Multi-technique combinations using a closure in time. Scientific Assembly of the International Association of Geodesy, 2021
Kodet, J.; Schreiber, U. & Klügel, T.
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Towards Clock Ties for a Global Geodetic Observing System.
Kodet, Jan; Schreiber, Ulrich; Klügel, Thomas & Eckl, Johann
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Satellite range finding by photon counting against optical time ruler. Quantum Optics and Photon Counting 2023, 9. SPIE.
Kodet, Jan; Schreiber, Ulrich & Eckl, Johann
