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  • 1.
    Bergstrand, Sten
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Herbertsson, Magnus
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Spetz, Jörgen
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Svantesson, Claes-Göran
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Haas, Rüdiger
    Chalmers University of Technology, Sweden.
    A gravitational telescope deformation model for geodetic VLBI2019In: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 93, no 5, p. 669-680Article in journal (Refereed)
    Abstract [en]

    We have measured the geometric deformations of the Onsala 20 m VLBI telescope utilizing a combination of laser scanner, laser tracker, and electronic distance meters. The data put geometric constraints on the electromagnetic raypath variations inside the telescope. The results show that the propagated distance of the electromagnetic signal inside the telescope differs from the telescope’s focal length variation, and that the deformations alias as a vertical or tropospheric component. We find that for geodetic purposes, structural deformations of the telescope are more important than optic properties, and that for geodetic modelling the variations in raypath centroid rather than focal length should be used. All variations that have been identified as significant in previous studies can be quantified. We derived coefficients to model the gravitational deformation effect on the path length and provide uncertainty intervals for this model. The path length variation due to gravitational deformation of the Onsala 20 m telescope is in the range of 7–11 mm, comparing elevation 0$$^{\circ }$$∘and 90$$^{\circ }$$∘, and can be modelled with an uncertainty of 0.3 mm.

  • 2.
    Ebenhag, Sven Christian
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Hedekvist, Per Olof
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Bergroth, Magnus
    SUNET, Sweden.
    Krehlik, Przemyslaw
    AGH University of Science and Technology, Poland.
    Sliwczynski, Lukasz
    AGH University of Science and Technology, Poland.
    Evaluation of Fiber Optic Time and Frequency Distribution System in a Coherent Communication Network2019In: IFCS/EFTF 2019 - Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper (Refereed)
    Abstract [en]

    A fiber-based time transfer between UTC(SP) and the VLBI-station at Onsala Space Observatory has been evaluated. The transfer uses a single wavelength in an active coherent DWDM-network in unidirectional duplex fibers and is routed through Reconfigurable Optical Add-Drop Multiplexers.

  • 3.
    Ebenhag, Sven-Christian
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Hedekvist, Per Olof
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jarlemark, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Time transfer between UTC(SP) and UTC(MIKE) using frame detection in fiber-optical communication networks2011In: 43rd Annual Precise Time and Time Interval Systems and Applications Meeting 2011, 2011, , p. 431-441Conference paper (Refereed)
  • 4.
    Ebenhag, Sven-Christian
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Hedekvist, Per Olof
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jarlemark, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Emardson, Ragne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Löthberg, Peter
    Measurements and Error Sources in Time Transfer Using Asynchronous Fiber Network2010In: IEEE Transactions on instrumentation and measurement, Vol. 59, no 7, p. 1918-1924Article in journal (Refereed)
  • 5.
    Emardson, Ragne
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Hedekvist, Per Olof
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Nilsson, Mattias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Ebenhag, Sven-Christian
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jarlemark, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Johansson, Jan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Pendrill, Leslie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Löthberg, Peter
    Nilsson, Håkan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Time Transfer by Passive Listening over 10 Gb/s Optical Fiber2008In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, no 11, p. 2495-2501Article in journal (Refereed)
  • 6.
    Hedekvist, Per Olof
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Ebenhag, Sven-Christian
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Bideberg, Glenn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Time and Frequency Activities at SP2013Conference paper (Other academic)
    Abstract [en]

    The national Time and Frequency laboratory of Sweden is a part of SP Technical Research Institute of Sweden since 1995. The laboratory is responsible for maintaining the official realization of Swedish standard time and the dissemination of it within Sweden. The objectives of the laboratory include supporting and making it accessible to Swedish industry and authorities with accurate measures of Time and Frequency by instrument calibration, knowledge-transfer, time dissemination, research and development. Swedish standard time is regulated by law to follow UTC as achieved and maintained by the BIPM. The atomic clocks that are used to implement UTC(SP), the realization of UTC in Sweden, are located at five different sites and are reported to TAI using data from TWSTFT and GNSS links. The activities in the Time and Frequency laboratory at SP is presently undergoing an expansion, with the construction of a new additional secure site, the implementation of a distributed time scale and the participation in the Galileo time scale.

  • 7.
    Hobiger, Thomas
    et al.
    Chalmers University of Technology, Sweden.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation. Chalmers University of Technology, Sweden.
    Rüdiger, Haas
    Chalmers University of Technology, Sweden.
    Koyama, Yasuhiro
    National Institute of Information and Communications Technology, Japan.
    Combining GPS and VLBI for inter-continental frequency transfer2015In: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 52, no 2, p. 251-261Article in journal (Refereed)
    Abstract [en]

    For decades the global positioning system (GPS) has been the only space geodetic technique routinely used for inter-continental frequency transfer applications. In the past very long baseline interferometry (VLBI) has also been considered for this purpose and the method's capabilities were studied several times. However, compared to GPS current VLBI technology only provides few observations per hour, thus limiting its potential to improve frequency comparisons. We therefore investigate the effect of combining GPS and VLBI on the observation level in order to draw the maximum benefit from the strength of each individual technique. As a test-bed for our study we use the CONT11 campaign observed in 2011. First we review the frequency transfer performance that can be achieved with independent technique-specific analyses, both with individual software packages and with the multitechnique software c5++. With this analysis approach both techniques, GPS and VLBI, show similar frequency link instabilities at the level of 10 -14 to 10 -15 (MDEV) on inter-continental baselines for averaging times of one day. Then we use the c5++ software for a combined analysis of GPS and VLBI data on the observation level. We demonstrate that our combination approach leads to small but consistent improvements for frequency transfer of up to 10%, in particular for averaging periods longer than 3000 s.

  • 8.
    Jaldehag, Kenneth
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Ebenhag, Sven-Christian
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Hedekvist, Per Olof
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Time transfer using frame detection in fiber-optical communication networks: New hardware2011In: 5th Joint Conference of the 65th IEEE International Frequency Control Symposium, IFCS 2011, 2011, , p. 5977323Conference paper (Refereed)
  • 9.
    Jaldehag, Kenneth
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Jarlemark, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Clock models for Kalman filtering2016Report (Other academic)
  • 10.
    Jaldehag, Kenneth
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Jarlemark, Per
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Further Evaluation of CGGTTS Time Transfer Software2019In: IFCS/EFTF 2019 - Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper (Refereed)
    Abstract [en]

    A new software tool for GNSS time transfer implementing the Common GNSS Generic Time Transfer Standard (CGGTTS) was developed by the time and frequency group at RISE Research Institutes of Sweden. The software is called RISEGNSS and converts RINEX observational data into CGGTTS data. It handles codes and carriers of the satellite navigation systems GPS, GLONASS, Galileo and BeiDou including the most important ranging codes for time transfer applications. The software is also prepared for single-frequency applications, and for the use of non-standard codes and carriers such as Galileo PRS and those from SBAS. The aim of the development is to provide an alternative to existing software and to support time transfer with new GNSS. This paper presents a full comparison of new versions of RISEGNSS and the well-established software R2CGGTTS, developed by the Royal Observatory of Belgium. The evaluation includes the linear combinations recommended in the CGGTTS standard for time transfer applications using GPS, GLONASS, Galileo and BeiDou. The aim of the evaluation is to support the development in making CGGTTS data compatible between different stand-alone software as well as those implemented in receivers, which is important to make Common-View (CV) time transfer results precise and accurate. The paper also presents CV time transfer results for three different baselines based on CGGTTS data obtained from the RISEGNSS software. The results include those obtained from dual-frequency code combinations of the four GNSS: GPS, Galileo, GLONASS and BeiDou. The results also include those of using standard single-frequency code observables as well as nonstandard codes and carriers such as L5 for GPS, E5b and E5 (Alt-BOC) for Galileo, G3 for GLONASS, and B3 for BeiDou. It finally studies the possibility and quality of using SBAS for time transfer. 

  • 11.
    Jaldehag, Kenneth
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Jarlemark, Per
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Evaluation of CGGTTS time transfer software using multiple GNSS constellations2018Conference paper (Refereed)
    Abstract [en]

    A new software tool for GNSS time transfer implementing the Common GNSS Generic Time Transfer Standard (CGGTTS) has been developed by the time and frequency group at RISE Research Institutes of Sweden. The software handles signals from the satellite navigation systems GPS, GLONASS, Galileo and BeiDou including the most important ranging codes for time transfer applications. The aim of the development is to provide an alternative to existing software and to support time transfer with new GNSS. The paper presents an evaluation of CGGTTS data calculated with the new software tool in comparison with those calculated using two other, independently developed software tools. It is shown that the results obtained from the different software agree to the sub-nanosecond level. Specifically, the agreement seen between individual GPS, Galileo and BeiDou CGGTTS data is at the 100- to 200-picosecond level. Similarly, GLONASS CGGTTS data agree to the sub-nanosecond level. Further, the paper presents a comparison between time transfer links for both long baselines and short, common-clock baselines obtained from a common view analysis of CGGTTS data from the four mentioned GNSS, as well as a combination of them. It finally discusses other features available from the RISE software, such as non-smoothed CGGTTS data, adoption of satellite orbit and clock products from the IGS as well as the results of an evaluation using linear combinations with non-standard CGGTTS codes and signals.

  • 12.
    Jiang, Zhiheng
    et al.
    BIPM Bureau International des Poids et Mesures, France.
    Zhang, Victor
    NIST National Institute of Standards and Technology, USA.
    Huang, Yi-Jiun
    Telecommunication Laboratories, Chinese Taipei.
    Achkar, Joseph
    Sorbonne Université, France.
    Piester, Dirk
    PTB, Germany.
    Lin, Shinn-Yan
    Telecommunication Laboratories, Chinese Taipei.
    Wu, Wenjun
    National Time Service Center, China.
    Naumov, Andrey
    Main Metrological Center for State Service of Time and Frequency, Russia.
    Yang, Sung-hoon
    Korea Research Institute of Standards and Science, South Korea.
    Nawrocki, Jerzy
    Space Research Center Astrogeodynamic Observatory, Poland.
    Sesia, Ilaria
    Istituto Nazionale di Ricerca Metrologica, Italy.
    Schlunegger, Christian
    Federal Institute of Metrology METAS, Switzerland.
    Yang, Zhiqiang
    National institute of Metrology, China.
    Fujieda, Miho
    NICT National Institute of Information and Communications Technology, Japan.
    Czubla, Albin
    Central Office of Measures, Poland.
    Esteban, Hector
    ROA Real Instituto y Observatorio de la Armada, Spain.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Whibberley, Peter
    NPL National Physical Laboratory, UK.
    Use of software-defined radio receiversin two-way satellite time and frequencytransfers for UTC computation2018In: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 55, p. 685-698Article in journal (Refereed)
    Abstract [en]

    Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for thegeneration of coordinated universal time (UTC). About 20 timing laboratories around theworld continuously operate TWSTFT using satellite time and ranging equipment (SATRE19)modems for remote time and frequency comparisons in this context. The precision of theSATRE TWSTFT as observed today is limited by an apparent daily variation pattern (diurnal)in the TWSTFT results. The observed peak-to-peak variation have been found as high as 2 nsin some cases. Investigations into the origins of the diurnals have so far provided no completeunderstanding about the cause of the diurnals. One major contributor to the diurnals, however,could be related to properties of the receive part in the modem. In 2014 and 2015, it wasdemonstrated that bypassing the receive part and the use of software-defined radio (SDR) receivers in TWSTFT ground stations (SDR TWSTFT) instead could considerably reduce boththe diurnals and the measurement noise.In 2016, the International Bureau of Weights and Measures (BIPM) and the ConsultativeCommittee for Time and Frequency (CCTF) working group (WG) on TWSTFT launched a pilotstudy on the application of SDR receivers in the TWSTFT network for UTC computation.The first results of the pilot study were reported to the CCTF WG on TWSTFT annualmeeting in May 2017, demonstrating that SDR TWSTFT shows superior performancecompared to that of SATRE TWSTFT for practically all links between participating stations.In particular, for continental TWSTFT links, in which the strongest diurnals appear, the useof SDR TWSTFT results in a significant suppression of the diurnals by a factor of betweentwo and three. For the very long inter-continental links, e.g. the Europe-to-USA links wherethe diurnals are less pronounced, SDR TWSTFT achieved a smaller but still significant gainof 30%. These findings are supported by an evaluation of some of the links with an alternatetechnique based on GPS signals (GPS IPPP) as reported in this paper.Stimulated by these results, the WG on TWSTFT prepared a recommendation for the 21stCCTF meeting, which proposed the introduction of SDR TWSTFT in UTC generation. WithCCTF approval of the recommendation, a roadmap was developed for the implementationof SDR TWSTFT in UTC generation. In accordance with the roadmap, most of the stationsthat participated in the pilot study have updated the SDR TWSTFT settings to facilitatethe use of SDR TWSTFT data in UTC generation. In addition, the BIPM conducted a finalevaluation to validate the long-term stability of SDR TWSTFT links, made test runs using theBIPM standard software for the calculation of UTC, now including SDR TWSTFT data, andstarted to calculate SDR TWSTFT time links as backup from October 2017. The use of SDRTWSTFT in UTC generation will begin in 2018.

  • 13.
    Jiang, Zhiheng
    et al.
    BIPM Bureau International des Poids et Mesures, France.
    Zhang, Victor S.
    NIST National Institute of Standards and Technology, USA.
    Huang, Yi Jiun
    TL National Standard Time and Frequency Laboratory, Taiwan.
    Achkar, Joseph
    Observatoire de Paris, France.
    Piester, Dirk
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Lin, Shinn Yan Calvin
    TL National Standard Time and Frequency Laboratory, Taiwan.
    Wu, Wenjun
    NTSC National Time Service Center, China.
    Naumov, Andrey
    Main Metrological Center for State Service of Time and Frequency, Russia.
    Yang, Sunghoon
    KRISS: Korea Research Institute of Standards and Science, South Korea.
    Nawrocki, Jerzy
    AOS Space Research Center, Poland.
    Sesia, Ilaria
    INRIM Istituto Nazionale di Ricerca Metrologica, Italy.
    Schlunegger, Christian
    Metas Federal Institute of Metrology, Switzerland.
    Yang, Zhiqiang
    NIM National Institute of Metrology, China.
    Fujieda, Miho
    NICT National Institute of Information and Communications Technology, Japan.
    Czubla, Albin
    Central Office of Measures, Poland.
    Esteban, Hector
    Real Instituto y Observatorio de la Armada, Spain.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Whibberley, Peter B.
    NPL National Physical Laboratory, UK.
    Use of software-defined radio receivers in two-way satellite time and frequency transfers for UTC computation2018In: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 55, no 5, p. 685-698Article in journal (Refereed)
    Abstract [en]

    Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal time (UTC). About 20 timing laboratories around the world continuously operate TWSTFT using satellite time and ranging equipment (SATRE19) modems for remote time and frequency comparisons in this context. The precision of the SATRE TWSTFT as observed today is limited by an apparent daily variation pattern (diurnal) in the TWSTFT results. The observed peak-to-peak variation have been found as high as 2 ns in some cases. Investigations into the origins of the diurnals have so far provided no complete understanding about the cause of the diurnals. One major contributor to the diurnals, however, could be related to properties of the receive part in the modem. In 2014 and 2015, it was demonstrated that bypassing the receive part and the use of software-defined radio (SDR) receivers in TWSTFT ground stations (SDR TWSTFT) instead could considerably reduce both the diurnals and the measurement noise. In 2016, the International Bureau of Weights and Measures (BIPM) and the Consultative Committee for Time and Frequency (CCTF) working group (WG) on TWSTFT launched a pilot study on the application of SDR receivers in the TWSTFT network for UTC computation. The first results of the pilot study were reported to the CCTF WG on TWSTFT annual meeting in May 2017, demonstrating that SDR TWSTFT shows superior performance compared to that of SATRE TWSTFT for practically all links between participating stations. In particular, for continental TWSTFT links, in which the strongest diurnals appear, the use of SDR TWSTFT results in a significant suppression of the diurnals by a factor of between two and three. For the very long inter-continental links, e.g. the Europe-to-USA links where the diurnals are less pronounced, SDR TWSTFT achieved a smaller but still significant gain of 30%. These findings are supported by an evaluation of some of the links with an alternate technique based on GPS signals (GPS IPPP) as reported in this paper. Stimulated by these results, the WG on TWSTFT prepared a recommendation for the 21st CCTF meeting, which proposed the introduction of SDR TWSTFT in UTC generation. With CCTF approval of the recommendation, a roadmap was developed for the implementation of SDR TWSTFT in UTC generation. In accordance with the roadmap, most of the stations that participated in the pilot study have updated the SDR TWSTFT settings to facilitate the use of SDR TWSTFT data in UTC generation. In addition, the BIPM conducted a final evaluation to validate the long-term stability of SDR TWSTFT links, made test runs using the BIPM standard software for the calculation of UTC, now including SDR TWSTFT data, and started to calculate SDR TWSTFT time links as backup from October 2017. The use of SDR TWSTFT in UTC generation will begin in 2018.

  • 14.
    Rieck, Carsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    A hardware accelerated 10GbE primary NTP-server2012In: European Frequency and Time Forum, EFTF 2012, 2012, , p. 387-391Conference paper (Refereed)
  • 15.
    Rieck, Carsten
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Haas, Rüdiger
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Johansson, Jan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    VLBI and GPS-based Time-Transfer Using Cont08 Data2010In: 6th IVS General Meeting, 2010, , p. 365-369Conference paper (Other academic)
  • 16.
    Rieck, Carsten
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Haas, Rüdiger
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Johansson, Jan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    VLBI time-transfer using Cont08 Data2010Conference paper (Other academic)
  • 17.
    Rieck, Carsten
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jaldehag, Kenneth
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jarlemark, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Haas, Rüdiger
    VLBI Frequency Transfer using CONT112012In: European Frequency and Time Forum (EFTF 2012), 2012, , p. 163-165Conference paper (Refereed)
  • 18.
    Rieck, Carsten
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jarlemark, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Haas, Rüdiger
    VLBI and GNSS Frequency Link Instabilities during CONT Campaigns2012In: IVS 2012 General Meeting Proceedings, 2012, , p. 425-429Conference paper (Other academic)
  • 19.
    Rieck, Carsten
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Jarlemark, Per
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Jaldehag, Kenneth
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Passive utilization of the TWSTFT technique2018Conference paper (Refereed)
    Abstract [en]

    As an active technique TWSTFT is limited in the number of concurrent users on the same communication channel. Using the transmissions of the reference network, passive users can observe the signals in a common view sense and by knowing the orbit of the relaying satellite, corrections describing the dynamic path delay can be used to estimate the clock difference between passive stations. Reliable orbit determination can be achieved using all the active measurements performed by the regular active users. For the EU/US network using Telesat Telstar 11N, the orbit estimation uncertainty is in the order of 1m for the area spanned by the contributing stations. The corresponding time uncertainty for a passive user is about 1 ns, slightly larger than achievable by active links. A passive use of TWSTFT may provide increased timing resiliency for a number of applications. The design of a passive ground station based on a SDR receiver is suggested.

  • 20.
    Rieck, Carsten
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Jarlemark, Per O.J.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Jaldehag, Kenneth
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Utilizing TWSTFT in a passive configuration2017In: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI, Institute of Electrical and Electronics Engineers Inc. , 2017, p. 219-234Conference paper (Refereed)
    Abstract [en]

    In this paper we suggest the passive usage of Two Way Satellite Time and Frequency Transfer (TWSTFT). In a passive configuration a receiver observes, possibly multiple, codes sent by the active users of a TWSTFT-network. Common view observations of the same signals by a pair of observers can be used to compare their local clocks. Similar to GNSS, the users need to know their local coordinates and the orbit of the satellite in order to reduce the measurements by the geometry. As the orbit is usually poorly known, it is essential to establish an infrastructure that provides the users with satellite ephemerides and appropriated correction models. In this initial study we use the ranging measurements performed by the active European network to TELSTAR 11N in order to estimate precise satellite positions. Residual ranges of the position estimates are well below 1 m. Based on the precise satellite positions and other regular TWSTFT measurements an extended Kepler description of the orbit is determined, which can be used to estimate ranges from the satellite to a passive user at arbitrary station positions and arbitrary epochs. A passive use of TWSTFT will enable us to increase the number of measurements without increasing the noise level on the transponder. It will also reach out to a new group of users, both commercial and scientific, which will benefit from current and future developments of TWSTFT. NMIs will be able to offer an independent method for robust distribution of their national time scales. © 2017 Institute of Electrical and Electronics Engineers Inc. All rights reserved.

  • 21.
    Svensson, Stefan
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Bideberg, Glenn
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Larsson, Bo
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    A PMU Calibration System2018In: CPEM 2018 - Conference on Precision Electromagnetic Measurements, 2018Conference paper (Refereed)
    Abstract [en]

    There is a need for traceable calibrations of Phasor measurement units, which measures the phase angle of power system signals with respect to the universal time. This paper describes the design of such a calibration system. The system utilizes a fast A-D converter, synchronized to the Swedish time and frequency realization. The speed and synchronization makes the calibration and adjustment fast and relatively straight-forward. Coaxial dividers and shunts are used for system control. The goal is a three-phase system with an angular uncertainty in the order of, or better than ±0.002° or ±100 ns.

1 - 21 of 21
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