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Stuttgart Mühlhausen, Germany

Rost M.,Physikalisch - Technische Bundesanstalt | Rost M.,German Aerospace Center | Piester D.,Physikalisch - Technische Bundesanstalt | Yang W.,National University of Defense Technology | And 4 more authors.
Metrologia | Year: 2012

We demonstrate the capability of accurate time transfer using optical fibres over long distances utilizing a dark fibre and hardware which is usually employed in two-way satellite time and frequency transfer (TWSTFT). Our time transfer through optical fibre (TTTOF) system is a variant of the standard TWSTFT by employing an optical fibre in the transmission path instead of free-space transmission of signals between two ground stations through geostationary satellites. As we use a dark fibre there are practically no limitations to the bandwidth of the transmitted signals so that we can use the highest chip rate of the binary phase-shift modulation available from the commercial equipment. This leads to an enhanced precision compared with satellite time transfer where the occupied bandwidth is limited for cost reasons. The TTTOF system has been characterized and calibrated in a common-clock experiment at PTB, and the combined calibration uncertainty is estimated as 74 ps. In a second step the remote part of the system was operated at Leibniz Universität Hannover, Institut für Quantenoptik (IQ) separated by 73 km from PTB in Braunschweig. In parallel, a GPS time transfer link between Braunschweig and Hannover was established, and both links connected a passive hydrogen maser at IQ with the reference time scale UTC(PTB) maintained in PTB. The results obtained with both links agree within the 1- uncertainty of the GPS link results, which is estimated as 0.72 ns. The fibre link exhibits a nearly ten-fold improved stability compared with the GPS link, and assessment of its performance has been limited by the properties of the passive maser. © 2012 BIPM & IOP Publishing Ltd. Source


Prochazka I.,Czech Technical University | Blazej J.,Czech Technical University | Kodet J.,Czech Technical University | Schreiber U.,TU Munich | And 2 more authors.
EFTF 2010 - 24th European Frequency and Time Forum | Year: 2010

We are presenting the new instrument, new technology available and new measurement technique proposal for the Galileo programme - optical detector for the laser time transfer. Combining the laser pulse emission times, propagation delays and satellite arrival times the ground to space clock comparison may be accomplished. The timing precision of the order of 1 × 10-12 seconds and a time transfer accuracy of 50 picoseconds is achievable. This precision and accuracy is at least one order of magnitude better in the optical region than in the radio frequency wavelength region. All the components of the proposed instruments are available in Europe, the ground segment of the proposed project is existing, the measurement techniques and data flow and processing procedures are well established. The implementation of new picosecond timing technologies and the laser time transfer into the Galileo programme will improve the precision and accuracy of the satellite on-board time scale and position prediction with unprecedent precision and accuracy. Both these facts will contribute to the Galileo system overall accuracy and performance and simultaneously will enable new experiments in fundamental physics. © 2010 IEEE. Source


Grop S.,CNRS Femto ST Institute | Bourgeois P.-Y.,CNRS Femto ST Institute | Rubiola E.,CNRS Femto ST Institute | Schafer W.,TimeTech GmbH | And 3 more authors.
Electronics Letters | Year: 2011

A report is presented on the measurement of a frequency synthesiser that provides round frequencies (10GHz, 5MHz, 100MHz) with high spectral purity from a cryocooled sapphire oscillator in the vicinity of 10GHz. The synthesiser and sapphire oscillator are a part of Elisa, a frequency reference that exhibits a stability of parts in 10-15 from 1s to 1000s integration time, designed and implemented for the European Space Agency. The synthesiser features low 1/f phase noise, -96dBc/Hz at 1Hz off the carrier at the 10GHz output, and -133dBc/Hz at 1Hz offset at the 100MHz output. © 2011 The Institution of Engineering and Technology. Source


Esteban H.,Real Instituto Y Observatorio Of La Armada Roa | Palacio J.,Real Instituto Y Observatorio Of La Armada Roa | Bauch A.,Physikalisch - Technische Bundesanstalt | Piester D.,Physikalisch - Technische Bundesanstalt | And 2 more authors.
EFTF 2012 - 2012 European Frequency and Time Forum, Proceedings | Year: 2012

Since 2010 ROA has supported the coordination of the EURAMET Technical Committee for Time and Frequency (TC-TF) Project 1156, GPSCALEU, a reaction from EURAMET TC-TF to Recommendation 2 of CCTF 2009: to study the characterization of GNSS equipment in use for establishing the time links between institutes contributing with their clocks to TAI. Starting that year, it was organized a GPS calibration campaign between three contributing laboratories: ROA (Spain), PTB (Germany) and INRIM (Italy). The time transfer results were achieved by using P3, and also carrier phase PPP comparison techniques. These results were also used to re-calibrate the TWSTFT (Two-Way Satellite Time and Frequency Transfer, TW for short) links between the involved laboratories, with an uncertainty slightly higher than GPS links. © 2012 IEEE. Source


Prochazka I.,Czech Technical University | Schreiber U.,TU Munich | Schafer W.,TimeTech GmbH
Advances in Space Research | Year: 2011

We are presenting the new instrument, new technology available and new measurement technique proposal for the Galileo programme - optical detector for the laser time transfer and one way laser ranging ground to space. Combining the laser pulse emission times, propagation delays and satellite arrival times the ground to space clock comparison may be accomplished. The timing precision of the order of 1 × 10-12 s and a time transfer accuracy of 50 ps is achievable. This precision and accuracy is at least one order of magnitude better in the optical region than in the radio frequency wavelength region. All the components of the proposed instruments are available in Europe, the ground segment of the proposed project is existing, the measurement techniques and data flow and processing procedures are well established. The implementation of new picosecond timing technologies and the laser time transfer into the Galileo programme will improve the precision and accuracy of the satellite on-board time scale and position prediction with unprecedent precision and accuracy. Both these facts will contribute to the Galileo system overall accuracy and performance and simultaneously will enable new experiments in fundamental physics. © 2010 COSPAR. Published by Elsevier Ltd. All rights reserved. Source

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