Ground-based demonstration of the European Laser Timing (ELT) experiment

Schreiber, K. U.; Procházka, Ivan; Lauber, Pierre; Hugentobler, Urs; Schäfer, W.; Cacciapuoti, L.; Nasca, R.

doi:10.1109/tuffc.2010.1471

Cited by 56 publications

(27 citation statements)

References 11 publications

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“…The optical time transfer in a free space is an alternative to the radiofrequency techniques of comparing of two time scales located on ground and in space [1] . One of the advantages of the optical approach is the possibility to evaluate the signal propagation delays in the atmosphere with very high precision and accuracy.…”

Section: Introductionmentioning

confidence: 99%

Photon counting delay stability as a key factor for optical time transfer

2013

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The concept and preliminary experimental results of photon counting based two-way optical time transfer are presented. It is based on free-space optical link delimited by a pair of SPAD-based single photon detectors and small reflectors injecting optical signals into the link alternately on two injection points. Several picosecond laser versions may be employed as signal source -laser diode 43 ps at 778 nm, fiber based laser 80 ps at 531 nm or both. Expected repetition rate of experiment is 5 kHz. The NPET timing devices are used to register detection events and custom software and algorithm are used to process measured data. The long term delay stability sub --picosecond range and small temperature drifts of all elements of measuring chain are crucial to obtain useful data for final time scale comparison in picosecond range. The experimental results from measurement of long term stability of detector delays, delay independence on position in detector active area, and new achievements in quenching techniques will be presented.

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Section: Introductionmentioning

confidence: 99%

Photon counting delay stability as a key factor for optical time transfer

2013

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“…The systematic error contribution of the atmospheric propagation of optical pulse is negligible on this distance. This calibration scheme was tested in a series of indoor experiments and in a real field operation [7]. The delays associated with the SLR Station in Wettzell, Germany, have been measured.…”

Section: Ground Segment Delays Calibrationmentioning

confidence: 99%

Identification and calibration of ground system biases in ground to space laser time transfer

Procházka

Blazej

Kodet

2015

2015 Joint Conference of the IEEE International Frequency Control Symposium &Amp; The European Frequency and Time Forum

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Laser time transfer is and attractive technique to transfer time ground to space with picosecond precision and systematic errors on the level of tens of picoseconds. Recently the European Laser Timing experiment is under construction in the frame of the European Space Agency mission Atomic Clock Ensemble in Space. The objective of this laser time transfer is synchronization of the ground based clocks and the clock on board the International Space Station with picosecond precision and the accuracy better than 50 picoseconds We are reporting on a progress in identification and calibration of the biases associated to both ground and space segment. To characterize the delays of a ground segment the Calibration Device has been developed and tested. It enables to calibrate the ground based laser systems for their systematic timing biases. As a result the ground to ground time transfer in an ELT experiment should be accomplished with systematic errors not higher than 25 picoseconds. To determine the delays of a space segment the new calibration procedure has been designed and tested as well. The calibration test results will be presented.

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“…The time transfer is based on SLR, where two-way time of flight measurements are used to establish the orbit of the ISS. Since the laser pulses are also detected and time tagged on the ACES timescale during the SLR measurement process, the timescale on the ground and the timescale of ACES can be synchronized with an expected accuracy of 100 ps [5]. The inherent high stability of the ACES clocks will also allow a non-common view time comparison, thus allowing to synchronize geodetic observatories over intercontinental baselines for demonstrating the common clock concept.…”

Section: Common Clock Conceptmentioning

confidence: 99%

On the importance of time and frequency in geodesy

Hugentobler¹

2013

2013 Joint European Frequency and Time Forum &Amp; International Frequency Control Symposium (EFTF/IFC)

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According to Friedrich Robert Helmert geodesy is the science of the measurement and mapping of the figure of the Earth. With the advent of the space age it was possible to establish a global reference frame, which can relate different locations across the entire Earth with an accuracy of currently about 1 cm with respect to each other. A rapid development of highly precise and stable frequency standards took place at the same time and is an important prerequisite for the actual quality of this global terrestrial reference frame. In fact all measurement techniques in modern space geodesy are based on precise time and frequency. Growing demands for the monitoring of global change as one of several examples of the importance of a highly resolved reference frame require more than one order of magnitude improvement over the existing level of quality. Optical clocks, optical frequency combs and near lossless time and frequency transfer have the potential to provide significant improvements of the individual techniques of space geodesy. This talk reviews how time and frequency impacts space geodesy and how the observation techniques may benefit from the recent progress in this field.

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Ground-based demonstration of the European Laser Timing (ELT) experiment

Cited by 56 publications

References 11 publications

Photon counting delay stability as a key factor for optical time transfer

Photon counting delay stability as a key factor for optical time transfer

Identification and calibration of ground system biases in ground to space laser time transfer

On the importance of time and frequency in geodesy

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