Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502349
Z. Jiang, W. Lewandowski
We present the new side-product of the monthly UTC computation: the long-term time links which is monthly published since Jan. 2010 and available on the BIPM ftp site: ftp://tai.bipm.org/TimeLink/LkC/LongTerm/. The techniques used for UTC generation are now TW, GPS and GLN. If they are considered independent, we can apply them in the investigations of the measurement uncertainties and the relative long-term variation in the link calibrations. 26 months' data have been collected and analyzed in this paper. For the short term measurement instability, we have similar conclusion as presently given in the section 6 of the BIPM Circular T. It seems however, for some baselines, exist long-term variations in the link calibrations. Limited by the knowledge of the raw data, we cannot explain the causes of this instability. Except for the extreme cases, most of the annual variations are within 2 ns. This is the limit of the uncertainty of the nowadays instrumentation and calibration and should not affect the UTC generations beyond its total uncertainty.
{"title":"Inter-comparison of the UTC time transfer links","authors":"Z. Jiang, W. Lewandowski","doi":"10.1109/EFTF.2012.6502349","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502349","url":null,"abstract":"We present the new side-product of the monthly UTC computation: the long-term time links which is monthly published since Jan. 2010 and available on the BIPM ftp site: ftp://tai.bipm.org/TimeLink/LkC/LongTerm/. The techniques used for UTC generation are now TW, GPS and GLN. If they are considered independent, we can apply them in the investigations of the measurement uncertainties and the relative long-term variation in the link calibrations. 26 months' data have been collected and analyzed in this paper. For the short term measurement instability, we have similar conclusion as presently given in the section 6 of the BIPM Circular T. It seems however, for some baselines, exist long-term variations in the link calibrations. Limited by the knowledge of the raw data, we cannot explain the causes of this instability. Except for the extreme cases, most of the annual variations are within 2 ns. This is the limit of the uncertainty of the nowadays instrumentation and calibration and should not affect the UTC generations beyond its total uncertainty.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"9 1","pages":"126-132"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73032082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502361
E. Portuondo-Campa, S. Kundermann, S. Lecomte
Increasing the compactness and robustness of laser stabilization systems is a critical need for the development of industrial applications of ultra-narrow linewidth lasers. In this aim, a compact optical setup based on the Pound-Drever-Hall scheme with a high finesse cavity was built with overall dimensions of L × W × H = 45 × 35 × 13 cm3. An external cavity diode laser (PLANEX™, RIO Inc.) as well as a distributed-feedback fiber laser (Koheras Adjustik, NKT photonics) were stabilized using this system. The frequency stability was evaluated using a similar setup as reference. The combined relative stability of the systems reached 7·10−15 at 1s.
{"title":"Compact Hz-level linewidth laser system","authors":"E. Portuondo-Campa, S. Kundermann, S. Lecomte","doi":"10.1109/EFTF.2012.6502361","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502361","url":null,"abstract":"Increasing the compactness and robustness of laser stabilization systems is a critical need for the development of industrial applications of ultra-narrow linewidth lasers. In this aim, a compact optical setup based on the Pound-Drever-Hall scheme with a high finesse cavity was built with overall dimensions of L × W × H = 45 × 35 × 13 cm<sup>3</sup>. An external cavity diode laser (PLANEX<sup>™</sup>, RIO Inc.) as well as a distributed-feedback fiber laser (Koheras Adjustik, NKT photonics) were stabilized using this system. The frequency stability was evaluated using a similar setup as reference. The combined relative stability of the systems reached 7·10<sup>−15</sup> at 1s.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"9 1","pages":"174-177"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83661372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502354
W. Aerts, P. Defraigne
In order to increase the reliability of the PTF at ROB and hence the reliability of UTC(ORB), the time was high for replacement of some major equipment. Obviously this was the ideal opportunity to give the PTF an upgrade and to solve some problems and issues. First the “old” PTF architecture was studied to pinpoint its shortcomings and possible improvements. Then a “new” PTF layout was defined and is gradually being implemented. This new PTF setup focuses on automatic (health) status monitoring, as well as on automatic control, of all operational devices. This should allow early detection of problems and prepares the PTF for future implementation of steering algorithms, such as a clock ensemble.
{"title":"Ongoing renewal of the ROB PTF","authors":"W. Aerts, P. Defraigne","doi":"10.1109/EFTF.2012.6502354","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502354","url":null,"abstract":"In order to increase the reliability of the PTF at ROB and hence the reliability of UTC(ORB), the time was high for replacement of some major equipment. Obviously this was the ideal opportunity to give the PTF an upgrade and to solve some problems and issues. First the “old” PTF architecture was studied to pinpoint its shortcomings and possible improvements. Then a “new” PTF layout was defined and is gradually being implemented. This new PTF setup focuses on automatic (health) status monitoring, as well as on automatic control, of all operational devices. This should allow early detection of problems and prepares the PTF for future implementation of steering algorithms, such as a clock ensemble.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"35 1","pages":"148-151"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80318224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502396
Z. Jiang, W. Lewandowski
This is a review paper. We revisited the key conceptions of the combined techniques used in the UTC generation: the combination of the GNSS and TWSTFT and that of the GPS and GLONASS code measurements.
{"title":"Use of multi-technique combinations in UTC/TAI time and frequency transfers","authors":"Z. Jiang, W. Lewandowski","doi":"10.1109/EFTF.2012.6502396","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502396","url":null,"abstract":"This is a review paper. We revisited the key conceptions of the combined techniques used in the UTC generation: the combination of the GNSS and TWSTFT and that of the GPS and GLONASS code measurements.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"49 1","pages":"335-339"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81791066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502433
J. Camparo, James O. Hagerman, T. Mcclelland
The generic, very long duration performance of rubidium (Rb) atomic clocks in space has implications ranging from deep-space missions to the outer planets to global-navigation satellite systems like Galileo and GPS. Here, using telemetry and frequency tuning data collected from spacecraft clocks that have been in operation continuously for anywhere from 2 to 11 years, we consider the performance and viability of Rb atomic clocks for very long duration space missions. While the results that we present are general in nature, and in no way system specific, they are nonetheless important and rarely available for space-mission planners.
{"title":"Long-term behavior of rubidium clocks in space","authors":"J. Camparo, James O. Hagerman, T. Mcclelland","doi":"10.1109/EFTF.2012.6502433","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502433","url":null,"abstract":"The generic, very long duration performance of rubidium (Rb) atomic clocks in space has implications ranging from deep-space missions to the outer planets to global-navigation satellite systems like Galileo and GPS. Here, using telemetry and frequency tuning data collected from spacecraft clocks that have been in operation continuously for anywhere from 2 to 11 years, we consider the performance and viability of Rb atomic clocks for very long duration space missions. While the results that we present are general in nature, and in no way system specific, they are nonetheless important and rarely available for space-mission planners.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"44 1","pages":"501-508"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82561111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502438
D. Calle, R. Piriz, C. Plantard, G. Cerretto
The promising potentialities for time and frequency transfer of a network solution of geodetic GNSS receivers located in National Timing Laboratories aiming at comparing their time scales at the maximum level of precision is presented.
{"title":"Smartphone application for the near-real time synchronization and monitoring of clocks through a network of GNSS receivers","authors":"D. Calle, R. Piriz, C. Plantard, G. Cerretto","doi":"10.1109/EFTF.2012.6502438","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502438","url":null,"abstract":"The promising potentialities for time and frequency transfer of a network solution of geodetic GNSS receivers located in National Timing Laboratories aiming at comparing their time scales at the maximum level of precision is presented.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"22 1","pages":"537-544"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80207209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502441
T. Schuldt, A. Keetman, K. Doringshoff, M. Reggentin, E. Kovalchuk, M. Nagel, M. Gohlke, U. Johann, D. Weise, A. Peters, C. Braxmaier
A variety of future space missions require ultra-stable optical frequency references. Setups based on Doppler-free spectroscopy of molecular iodine offer frequency stabilities in the 10−15 domain at longer integration times and have the potential to be realized space compatible on a relatively short time scale. We present a compact optical frequency reference using modulation-transfer spectroscopy of molecular iodine near 532 nm. Using a specific assembly-integration technology, this setup takes into account space mission related criteria such as compactness, robustness, MAIVT and environmental influences. With this setup, a frequency stability of 3 · 10−15 at integration times between 100 s and 10.000 s was demonstrated in a first measurement.
{"title":"An ultra-stable optical frequency reference for space applications","authors":"T. Schuldt, A. Keetman, K. Doringshoff, M. Reggentin, E. Kovalchuk, M. Nagel, M. Gohlke, U. Johann, D. Weise, A. Peters, C. Braxmaier","doi":"10.1109/EFTF.2012.6502441","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502441","url":null,"abstract":"A variety of future space missions require ultra-stable optical frequency references. Setups based on Doppler-free spectroscopy of molecular iodine offer frequency stabilities in the 10−15 domain at longer integration times and have the potential to be realized space compatible on a relatively short time scale. We present a compact optical frequency reference using modulation-transfer spectroscopy of molecular iodine near 532 nm. Using a specific assembly-integration technology, this setup takes into account space mission related criteria such as compactness, robustness, MAIVT and environmental influences. With this setup, a frequency stability of 3 · 10−15 at integration times between 100 s and 10.000 s was demonstrated in a first measurement.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"160 1","pages":"554-558"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77270037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502374
Y. Le Coq, W. Zhang, G. Santarelli, M. Fischer, R. Holzwarth
We present here a detailed investigation of a commercial-core Erbium-doped fiber-based femtosecond laser optical frequency comb equipped with an intra-cavity Electro-Optics modulator. This device allows rapid feed-back on the laser's repetition rate, enabling reaching the narrow-linewidth regime when locked to a ultra-high spectral purity optical continuous wave reference. Our study makes use of transfer functions analysis to characterize the laser dynamic response and the residual unavoidable cross talks. In a second part, we also present some results which show how to combine the signals from two photodetector to obtain a very low amplitude-phase conversion detection of the repetition rate, which is very useful in the context of low phase noise microwave generation with optical frequency combs.
{"title":"Investigation of an optical frequency comb with intracavity EOM and optimization of microwave generation","authors":"Y. Le Coq, W. Zhang, G. Santarelli, M. Fischer, R. Holzwarth","doi":"10.1109/EFTF.2012.6502374","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502374","url":null,"abstract":"We present here a detailed investigation of a commercial-core Erbium-doped fiber-based femtosecond laser optical frequency comb equipped with an intra-cavity Electro-Optics modulator. This device allows rapid feed-back on the laser's repetition rate, enabling reaching the narrow-linewidth regime when locked to a ultra-high spectral purity optical continuous wave reference. Our study makes use of transfer functions analysis to characterize the laser dynamic response and the residual unavoidable cross talks. In a second part, we also present some results which show how to combine the signals from two photodetector to obtain a very low amplitude-phase conversion detection of the repetition rate, which is very useful in the context of low phase noise microwave generation with optical frequency combs.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"10 1","pages":"238-241"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79643238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502436
W. Lange
Pseudolites are GNSS transmitters that have a fixed position on the ground and transmit original satellite signals. Very often pseudolites are used around airports and harbors to ease the navigation and increase integrity and availability of satellite navigation systems. Pseudolites are also used in the European “Gate”- Projects. “GATE” is the name of a Galileo test bed where several pseudolites are located around a valley in southeast Bavaria transmitting Galileo signals so that receivers are able to use Galileo signals for testing purpose in “real live” before the satellites are in the sky. Besides this first Gate project a number of similar pseudolite projects have been established. One of these projects is named “aviation gate” and is located at the research airport of Braunschweig.
{"title":"Very precise synchronization of distributed pseudolites","authors":"W. Lange","doi":"10.1109/EFTF.2012.6502436","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502436","url":null,"abstract":"Pseudolites are GNSS transmitters that have a fixed position on the ground and transmit original satellite signals. Very often pseudolites are used around airports and harbors to ease the navigation and increase integrity and availability of satellite navigation systems. Pseudolites are also used in the European “Gate”- Projects. “GATE” is the name of a Galileo test bed where several pseudolites are located around a valley in southeast Bavaria transmitting Galileo signals so that receivers are able to use Galileo signals for testing purpose in “real live” before the satellites are in the sky. Besides this first Gate project a number of similar pseudolite projects have been established. One of these projects is named “aviation gate” and is located at the research airport of Braunschweig.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"31 1","pages":"522-528"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80360229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-23DOI: 10.1109/EFTF.2012.6502427
F. Mubarak, E. Dierikx
A completely automated system has been designed to calibrate path delays in a two way satellite time and frequency transfer (TWSTFT) ground station. The heart of this delay calibration system is a dual bidirectional up/down converter that converts the modulated pseudo random noise (PRN) code from 70 MHz to Ku-band (10 GHz to 14 GHz) frequencies and vice versa. Besides the usual transmit (Tx) and receive (Rx) paths in the TWSTFT system, the dual bi-directional up/down converter offers two additional independent transmit and receive paths. These additional paths allow performing different independent loop delay measurements within the station from which the individual path delays can be calculated.
{"title":"Delay calibration system for a two way satellite time & frequency transfer station","authors":"F. Mubarak, E. Dierikx","doi":"10.1109/EFTF.2012.6502427","DOIUrl":"https://doi.org/10.1109/EFTF.2012.6502427","url":null,"abstract":"A completely automated system has been designed to calibrate path delays in a two way satellite time and frequency transfer (TWSTFT) ground station. The heart of this delay calibration system is a dual bidirectional up/down converter that converts the modulated pseudo random noise (PRN) code from 70 MHz to Ku-band (10 GHz to 14 GHz) frequencies and vice versa. Besides the usual transmit (Tx) and receive (Rx) paths in the TWSTFT system, the dual bi-directional up/down converter offers two additional independent transmit and receive paths. These additional paths allow performing different independent loop delay measurements within the station from which the individual path delays can be calculated.","PeriodicalId":6409,"journal":{"name":"2012 European Frequency and Time Forum","volume":"16 1","pages":"469-476"},"PeriodicalIF":0.0,"publicationDate":"2012-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87924023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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