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Le Touquet – Paris-Plage, France

Cerretto G.,INRIM - Istituto Nazionale di Ricerca Metrologica | Tavella P.,INRIM - Istituto Nazionale di Ricerca Metrologica | Lahaye F.,Natural Resources Canada | Mireault Y.,Natural Resources Canada | Rovera D.,LNE SYRTE
Proceedings of the IEEE International Frequency Control Symposium and Exposition | Year: 2011

The Precise Point Positioning (PPP) time-transfer technique requires the availability of precise estimates of GNSS satellite orbits and clock offsets. Several such products are available from the International GNSS Service (IGS), each having their own characteristics: robustness, update rate, latency and satellite clock offset time interval. The most frequently updated IGS products are the Ultra Rapid products, which are generated four times a day with a latency of three hours. Natural Resources Canada (NRCan) contributes its own Ultra Rapid GPS product to the IGS for combination. However, the underlying processes running at NRCan generate products much more frequently 24 times a day with a latency of 90 minutes, offering an opportunity for more timely time-transfer results when used in PPP. INRIM and NRCan hereby assess the potential of using the PPP with the NRCan Ultra Rapid GPS products to serve as a short latency time-transfer tool. A specific experiment has been set up, where the NRCan Ultra Rapid GPS products, as well as all currently available IGS products, are used in PPP time transfer between selected IGS stations collocated in timing laboratories. Results and relative merits are compared in light of their respective delivery and frequency stability characteristic, in view of designing an automated near real-time monitoring system to assist timing laboratories in operational maintenance of frequency standards and time scales dissemination to external users. © 2011 IEEE. Source


Hrabina J.,Institute of Scientific Instruments | Sarbort M.,Institute of Scientific Instruments | Hola M.,Institute of Scientific Instruments | Cip O.,Institute of Scientific Instruments | And 4 more authors.
2016 European Frequency and Time Forum, EFTF 2016 | Year: 2016

This work is oriented to comparison of methods for iodine absorption cells quality evaluation. Optical frequency references based on molecular iodine represent one of the most used references for stabilizion of laser standards working at visible spectral range. Unfortunately iodine is a media with very high sensitivity to contamination so the chemical purity of iodine cells must be preciselly controlled. Traditional methods for iodine absorption cells quality checking have several difficulties and disadvantages, these problems complicate their common using in labs. Due to this reason we propose an alternative method of spectral linewidths measurement, which overcomes these difficulties of traditionally used approaches and which serves as a tool for iodine cells quality evaluation. In this work we present the results of comparison of two laser induced fluorescence setups (with and without the compensation for the laser source spectral mode-hops) with proposed method of selected hyperfine transition linewidth measurements and we discuss advantages and limitations of these methods for practical using. © 2016 IEEE. Source


Laas-Bourez M.,University of Nice Sophia Antipolis | Samain E.,University of Nice Sophia Antipolis | Courde C.,University of Nice Sophia Antipolis | Oneto J.-L.,University of Nice Sophia Antipolis | And 5 more authors.
2013 Joint European Frequency and Time Forum and International Frequency Control Symposium, EFTF/IFC 2013 | Year: 2013

The Time Transfer by Laser Link (T2L2)[1) experiment aim to synchronise remote ultra stable clocks over large-scaled distances using two laser ranging stations. T2L2 ultimate time transfer capability can only be demonstrate with a picosecond range ground mastering. We focus this year in knowledge and equipment improvement to perform a T2L2 time transfer with accuracy and stability of a few picoseconds. A deep analysis of signals stability has been carried out this year in the time and frequency laboratory in Plateau de Calern. The aim was to better understand the limits and hardware configuration and to enhance time and frequency distribution for T2L2 experiment. We showed phase noise and stability problem on our H-maser distribution. Final measures were conducted in October in collaboration with SYRTE. Then a complete equipment reorganisation was done. This paper focus on the time and frequency laboratory characterization before and after the reorganisation. We introduce our new equipments and present our new H-maser time scale and discuss the performances obtained. © 2013 IEEE. Source


Delporte J.,French National Center for Space Studies | Suard N.,French National Center for Space Studies | Uhrich P.,LNE SYRTE | Tuckey P.,LNE SYRTE
2013 Joint European Frequency and Time Forum and International Frequency Control Symposium, EFTF/IFC 2013 | Year: 2013

EGNOS is the European Satellite Based GPS Augmentation System. It generates its own time scale (ENT) that is steered to GPS time. The time offset between ENT and UTC (actually UTC(OP)) is contained in EGNOS Message Type 12. The aim of this paper is to validate the content of this message and to present the performances of ENT with respect to UTC and GPS time over more than 4 years. © 2013 IEEE. Source


Thomas M.,French National Laboratory of Metrology and Testing | Espel P.,French National Laboratory of Metrology and Testing | Ziane D.,French National Laboratory of Metrology and Testing | Pinot P.,French National Conservatory of Arts and Crafts | And 5 more authors.
Metrologia | Year: 2015

After separate developments of the different elements with continuous characterizations and improvements, the LNE watt balance has been assembled. This paper describes the system in detail and gives its first measurements of the Planck's constant h. The value determined in air is h = 6.626 068 8(20) × 10-34 Js which differs in relative terms by -0.05 × 10-7 from the h90 value and by -1.1 × 10-7 from that of the 2010 CODATA adjustment of h. The relative standard uncertainty associated is 3.1 × 10-7. © 2015 BIPM & IOP Publishing Ltd. Source

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