TimeTech GmbH

Stuttgart Mühlhausen, Germany

TimeTech GmbH

Stuttgart Mühlhausen, Germany

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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.


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.


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.


Schreiber K.U.,TU Munich | Prochazka I.,Czech Technical University | Lauber P.,TU Munich | Hugentobler U.,TU Munich | And 3 more authors.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2010

The development of techniques for the comparison of distant clocks and for the distribution of stable and accurate time scales has important applications in metrology and fundamental physics research. Additionally, the rapid progress of frequency standards in the optical domain is presently demanding additional efforts for improving the performances of existing time and frequency transfer links. Present clock comparison systems in the microwave domain are based on GPS and two-way satellite time and frequency transfer (TWSTFT). European Laser Timing (ELT) is an optical link presently under study in the frame of the ESA mission Atomic Clock Ensemble in Space (ACES). The on-board hardware for ELT consists of a corner cube retro-reflector (CCR), a single-photon avalanche diode (SPAD), and an event timer board connected to the ACES time scale. Light pulses fired toward ACES by a laser ranging station will be detected by the SPAD diode and time tagged in the ACES time scale. At the same time, the CCR will re-direct the laser pulse toward the ground station providing precise ranging information. We have carried out a ground-based feasibility study at the Geodetic Observatory Wettzell. By using ordinary satellites with laser reflectors and providing a second independent detection port and laser pulse timing unit with an independent time scale, it is possible to evaluate many aspects of the proposed time transfer link before the ACES launch. © 2006 IEEE.


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.


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.


Schafer W.,TimeTech GmbH | Feldmann T.,TimeTech GmbH
Journal of Physics: Conference Series | Year: 2016

This paper reviews key characteristics and requirements for Two-Way Satellite Time and Frequency Transfer (TWSTFT) links. The outline and perspective of two concepts are described: 1. The classical bend-pipe transponder, without special equipment on board, with the potential of 10-17/day frequency transfer uncertainty; 2. The ACES-MWL (Atomic Clock Ensemble in Space Microwave Link) like active on-board equipment, with the potential down to few 10-19/day, using both high-rate modulation and carrier-phase. An outlook to advanced links is given. The aim of these proposed links is to provide a unique platform for the demanding requirements in the field of time and frequency metrology and to support improved orbit determination and relativistic geodesy for the next decades.


Feldmann T.,TimeTech GmbH | Balu A.,TimeTech GmbH | Molard C.,TimeTech GmbH | Schafer W.,TimeTech GmbH | Piester D.,Physikalisch - Technische Bundesanstalt
EFTF 2012 - 2012 European Frequency and Time Forum, Proceedings | Year: 2012

Two-Way Satellite Time and Frequency Transfer (TWSTFT) using geostationary telecommunication satellites has become an important technique for comparing remote timescales. There is a need for periodic calibration of the signal delays along the links which are part of the network for the realization of the International Atomic Time (TAI). In order to minimize the efforts of such TWSTFT calibration campaigns, TimeTech GmbH has assembled a mobile station on a trailer. The trailer contains the usual TWSTFT equipment, including the two-way modem, the up/down converters, filters, and amplifiers, as well as monitoring systems, air conditioner, and weather sensors. The steerable antenna is mounted on top of the trailer. The 1 PPS and 10 MHz signals required as input to the TWSTFT equipment are transferred from inside the timing laboratory by an optical link and two reference generators in a master-slave configuration. © 2012 IEEE.


Grop S.,CNRS Femto ST Institute | Schafer W.,TimeTech GmbH | Bourgeois P.-Y.,CNRS Femto ST Institute | Kersale Y.,CNRS Femto ST Institute | And 3 more authors.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2011

This article reports on the long-term frequency stability characterization of a new type of cryogenic sapphire oscillator using an autonomous pulse-tube cryocooler as its cold source. This new design enables a relative frequency stability of better than 4.5 × 10-15 over one day of integration. To the best of our knowledge, this represents the best long-term frequency stability ever obtained with a signal source based on a macroscopic resonator. © 2011 IEEE.


Piester D.,Physikalisch - Technische Bundesanstalt | Bauch A.,Physikalisch - Technische Bundesanstalt | Becker J.,Physikalisch - Technische Bundesanstalt | Feldmann T.,TimeTech GmbH | And 7 more authors.
Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI | Year: 2014

The recent activities in the field of time and frequency dissemination and applications at PTB were directed towards an improvement in quality and reliability of the offered services. As a foundation of its work, PTB has substantially improved the quality of its local realization of Coordinated Universal Time UTC(PTB). Since February 2010 UTC(PTB) has been derived from an active hydrogen maser steered in frequency by PTB's primary fountain clocks. During the time between July 2010 and July 2014 the time difference UTC - UTC(PTB) was always less than 9 ns. UTC(PTB) serves as the basis for all of PTB's time services and international time comparisons. PTB's time services comprise the operation of NTP time servers, a telephone time service and the standard frequency and time dissemination by the low frequency transmitter DCF77. In order to be able to enhance the security of PTB's NTP service, PTB is currently working within the Internet Engineering Task Force (IETF) on the standardization of a security protocol that enables secure authentication of NTP time-servers and integrity of the time synchronization packets. Since 2010, PTB's telephone/modem time service has received a surprisingly increasing number of requests. To accommodate these demands a second device was installed in June 2012 and a third one is held available as a hot backup. Since 2013, about 1800 accesses per day have been processed. The standard frequency and legal time transmitter DCF77 is still the most prominent part of PTB's time services. The number of operational receivers in Germany and Europe is estimated to be more than 100 million. Thus, a new contract was placed with the operator of the transmitter facilities ensuring guaranteed service until 2021. On the international scene, PTB participated in a number of calibration campaigns to ensure time scale comparisons with uncertainties at the nanosecond level. These comprise two-way satellite time and frequency transfer (TWSTFT) calibration campaigns within Europe, TWSTFT calibration campaigns organized by the U.S. Naval Observatory (USNO), and GNSS calibrations organized by the Bureau International des Poids et Mesures (BIPM). Furthermore, a GPS calibration setup assembled at PTB has been shipped to several metrology laboratories.

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