Ändra sökning
Avgränsa sökresultatet
1 - 30 av 30
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Alissa, S.
    et al.
    Lantmäteriet, Sweden.
    Håkansson, M.
    Lantmäteriet, Sweden.
    Rieck, Carsten
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Dutta, Uttama
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Nord, Stefan
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Bergljung, P.
    Saab TransponderTech, Sweden.
    Bagge, A.
    Saab TransponderTech, Sweden.
    Distribution of the adapted-NRTK correction data via VDES for the shipping navigation safety2021Ingår i: Proceedings of the 34th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS+ 2021, Institute of Navigation , 2021, s. 521-534Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this study the maritime communication system VDES (VHF Data Exchange System) is proposed to distribute Network-RTK (NRTK) correction data to shipborne GNSS receivers in fairways, port areas, or inland water ways. The transport layer used for transmission of VDES messages (related to the standard IEC61162-450) is the UDP multicast protocol. This makes it possible to transmit the RTCM packages from the VDES transponder to the shipborne GNSS receivers as a UDP payload without any additional formatting. In order to minimize the impact on the overall VDES data capacity in a local service area, NRTK correction data shall at most occupy a single VDES slot with a net capacity of 650 bytes denoted Link ID 19. This is the fastest link in VDES. Update rates may vary but are preferably at 1Hz. However, depending on the number of visible satellites NRTK correction data size changes instantly and the data rate can therefore sometimes be in excess of 1000 byte/s per reference station to be distributed. In order to comply with the VDES requirements, the Lantmäteriet Adjustment Solution (LAS) for GNSS correction data adjustment was developed and is presented in this paper. The responsibility of this solution is to produce a correction data stream that complies with the bandwidth limitation of 650 bytes/s. To provide corrections for a potentially large number of users, dissemination is done by broadcasting corrections for a grid of VRSs. The proposed solution has therefore also the capability to combine several correction data streams from several Virtual Reference Stations (VRSs) into one single correction data stream. To reduce the required data rate, the LAS has the ability to filter streamed GNSS correction data in the RTCM3 MSM format constellation-wise, satellite-wise, and signal-wise. The objective is to achieve optimal performance in terms of accuracy for the ship's differential positioning solution, while at the same time adhering to constraints that might locally apply for individual transmitters. For this paper LAS was configured to interface with the SWEPOS to provide reference data to static and kinematic testing scenarios. The results presented here were obtained using RTK post-processing with RTKLib for a combination of GPS and Galileo multi-frequency observations. Results indicated that LAS solution can achieve robust positioning performance with decimeter-level accuracy which meet the requirements expected for the navigation safety at Sea. Adapted-NRTK correction data (LAS data) via VDES has the potential to be part of a world-wide standard VDES application for all vessels sailing under SOLAS and for ships that voluntarily uses VDES in the near future (inland, yachts, navies, leisure).

  • 2.
    Bergstrand, Sten
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Herbertsson, Magnus
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Spetz, Jörgen
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Svantesson, Claes-Göran
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Haas, Rüdiger
    Chalmers University of Technology, Sweden.
    A gravitational telescope deformation model for geodetic VLBI2019Ingår i: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 93, nr 5, s. 669-680Artikel i tidskrift (Refereegranskat)
    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.

  • 3.
    Dimarcq, N.
    et al.
    Université Côte d’Azur, France.
    Hedekvist, Per Olof
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Ashby, N
    NIST, USA.
    Roadmap towards the redefinition of the second2024Ingår i: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 61, nr 1, artikel-id 012001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper outlines the roadmap towards the redefinition of the second, which was recently updated by the CCTF Task Force created by the CCTF in 2020. The main achievements of optical frequency standards (OFS) call for reflection on the redefinition of the second, but open new challenges related to the performance of the OFS, their contribution to time scales and UTC, the possibility of their comparison, and the knowledge of the Earth’s gravitational potential to ensure a robust and accurate capacity to realize a new definition at the level of 10−18 uncertainty. The mandatory criteria to be achieved before redefinition have been defined and their current fulfilment level is estimated showing the fields that still needed improvement. The possibility to base the redefinition on a single or on a set of transitions has also been evaluated. The roadmap indicates the steps to be followed in the next years to be ready for a sound and successful redefinition.

    Ladda ner fulltext (pdf)
    fulltext
  • 4.
    Dutta, Uttama
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Håkansson, M.
    Lantmäteriet, Sweden.
    Gerbeth, D.
    German Aerospace Center, Germany.
    Alissa, S.
    Lantmäteriet, Sweden.
    Nord, Stefan
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Satellite selection in the context of network RTK for limited bandwidth applications2021Ingår i: Proceedings of the 34th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS+ 2021, Institute of Navigation , 2021, s. 2474-2492Konferensbidrag (Refereegranskat)
    Abstract [en]

    The increasing number of modernized GNSS signals and the availability of multi-constellation receivers are crucial for improvements of both precision and robustness of GNSS based positioning. However, the abundance of GNSS observations is not always useable as applications, using differential positioning or other techniques, may have limitations with respect to computational resources or communication bandwidth for reference data, and therefore require a qualified selection of a subset of observations for positioning. This paper is based on the work conducted in the project PREParE SHIPS funded by the European Union Agency for the Space Programme (EUSPA) on the specific application of Maritime Navigation using Network Real Time Kinematic (NRTK) and will focus on the satellite selection algorithms of the Prepare Ships dissemination solution. This study is motivated by data rate requirements and restrictions of the VDES dissemination solution developed in Prepare Ships. The restricted data rate for dissemination of RTK observations via VDES implies the need for a qualified pre-selection of satellite subsets to match the available bandwidth and the requirements of the positioning system. For this, multiple algorithms have been developed and tested in static and dynamic scenarios. Optimization techniques for height (for vertical position), two and three dimensions were examined. Different weighting schemes were used. During the evolution of the satellite selection study, it was concluded that it is necessary to retain satellites with the highest elevation as this will empirically improve integer ambiguity resolution for position fixing. Also fixing a minimum number of satellites for each constellation was required to enable a fair weightage to the different constellations used. Such algorithms should prove to be very useful for research on various Network RTK applications which require/prefer limited bandwidth such as for cadastral surveying and mapping, for airborne geo-referencing of aerial mapping data using Unmanned Aerial Vehicles (UAV) and on the road and sea for positioning and navigation of automated transport. Additionally, these algorithms could also be extended to consider satellite visibility in e.g. urban areas (i.e. urban canyons) by inclusion of true surface information for more robust GNSS positioning in automated transport applications [1]. This could either be for pre-evaluation or for dynamically considering spatial information. While this work is a part of PREParE SHIPS, it is also motivated by a more general applicability of the algorithms presented for other similar applications. RTK correction dissemination with limited bandwidth requirements is very promising for RTK research and therefore this study on optimized selection of satellite subsets is of vital importance and could tap multiple opportunities of huge potential such as those involving NRTK or combination of Precise Point Positioning with RTK. © 2021 Proceedings of the 34th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS+ 2021. 

  • 5.
    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 networks2011Ingår i: 43rd Annual Precise Time and Time Interval Systems and Applications Meeting 2011, 2011, , s. 431-441Konferensbidrag (Refereegranskat)
  • 6.
    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 Network2010Ingår i: IEEE Transactions on instrumentation and measurement, Vol. 59, nr 7, s. 1918-1924Artikel i tidskrift (Refereegranskat)
  • 7.
    Ebenhag, Sven-Christian
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Hedekvist, Per Olof
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    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 Network2019Ingår i: 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. , 2019Konferensbidrag (Refereegranskat)
    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.

  • 8.
    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 Fiber2008Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, nr 11, s. 2495-2501Artikel i tidskrift (Refereegranskat)
  • 9.
    Hedekvist, Per Olof
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Ebenhag, Sven-Christian
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Wallberg, D.
    Sunet, Sweden.
    Bergroth, M.
    NORDUnet, Sweden.
    Fiber Optic Time Transfer from UTC(k) to a VLBI Antenna in a Coherent Communication Network2022Ingår i: 2022 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium, EFTF/IFCS 2022 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2022Konferensbidrag (Refereegranskat)
    Abstract [en]

    The local time scale at Onsala Space Observatory is connected to UTC(SP) through a White Rabbit time transfer system operating on the Swedish University Computer Network SUNET. The time transfer enables a robust synchronization of the VLBI and the IGS stations operating at the observatory and can potentially improve the reliability and availability of traceable time at sufficient accuracy. Several months of data are gathered to evaluate long term events and stability metrics. 

  • 10.
    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 SP2013Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 11.
    Hedekvist, Per Olof
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Rieck, Carsten
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Jaldehag, Kenneth
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Backefeldt, Jan
    TeliaSonera AB, Sweden.
    Experimental data from NTP-monitoring and uncertainty estimation in nationwide network2014Ingår i: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI, Institute of Electrical and Electronics Engineers Inc. , 2014, s. 52-56Konferensbidrag (Refereegranskat)
    Abstract [en]

    Using network-time-protocol, NTP, to synchronize electronics has its limitations. Even if the NTP-server is a Stratum 1 operated by a responsible agent and connected to a reliable source, the asymmetries in the network and the influence by data traffic congestions limit the accuracy to the order of 10 ms or worse. The large uncertainty of a single request can be compensated by repetition, but to be useful the local oscillator must be more stable than the occurrence of congestions in the network. Even then, there is a remaining doubt on the accuracy of the time received by the client. In principle the time achieved from an NTP-server is to be seen as unreliable for legal purposes, if no feedback estimates of the uncertainties are acquired of the transmission. Experimental data present how this limitation has improved, at least statistically, through the continuous upgrade of data bandwidth in one of Sweden's back-bone networks. Even though data over Internet also increases, it appears that the detrimental effects of the network on NTP accuracy have decreased. Since 2011, SP have monitored a number of NTP-servers operated by TeliaSonera and logged the response compared to the realization of the national timescale in Sweden (UTC(SP)). All NTP-servers used in this evaluation are commercial, off-the-shelf products with stratum 1 synchronization. The reference NTP-server and NTP-logger are located in SP premises in Borås, with a virtual private network connection to all servers, and thus sharing the bandwidth of the network between server and client. The NTP-logger is customized and includes equipment for independent measurements of the round-trip-delay. The uncertainty of each server, as achieved when polled from Borås, is calculated. The results present how the precision improves with an order of magnitude during the last three years by evaluating maximum daily variations. The improvements during the years have decreased the uncertainty and enhanced the accuracy to stable levels in ms to sub-ms range. This paper will further study and present the performance of the NTP-monitoring, with reported offset and uncertainty. It serves as an empirical reference on network improvements enabling better performance of NTP-synchronization.

  • 12.
    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 transfer2015Ingår i: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 52, nr 2, s. 251-261Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 13.
    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 hardware2011Ingår i: 5th Joint Conference of the 65th IEEE International Frequency Control Symposium, IFCS 2011, 2011, , s. 5977323Konferensbidrag (Refereegranskat)
  • 14.
    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 filtering2016Rapport (Övrigt vetenskapligt)
    Ladda ner fulltext (pdf)
    fulltext
  • 15.
    Jaldehag, Kenneth
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Jarlemark, Per
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Further Evaluation of CGGTTS Time Transfer Software2019Ingår i: 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. , 2019Konferensbidrag (Refereegranskat)
    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. 

  • 16.
    Jaldehag, Kenneth
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Jarlemark, Per
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Evaluation of CGGTTS time transfer software using multiple GNSS constellations2018Konferensbidrag (Refereegranskat)
    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.

  • 17.
    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, Säkerhet och transport, Mätteknik.
    Whibberley, Peter B.
    NPL National Physical Laboratory, UK.
    Use of software-defined radio receivers in two-way satellite time and frequency transfers for UTC computation2018Ingår i: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 55, nr 5, s. 685-698Artikel i tidskrift (Refereegranskat)
    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.

  • 18.
    Nord, Stefan
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Tidd, James
    Waysure Sweden AB, Sweden.
    Gunnarsson, Fredrik
    Ericsson Research, Sweden.
    Alissa, Samieh
    Lantmäteriet, Sweden.
    Rieck, Carsten
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Hanquist, Carl-Henrik
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Johansson, Viktor
    RISE Research Institutes of Sweden, Säkerhet och transport, Fordon och automatisering.
    Hammenstedt, Jimmy
    Volvo Technology AB, Sweden.
    Hoxell, Fredrik
    Scania CV AB, Sweden.
    Larsson, Christian
    Einride, Sweden.
    Chaisset, Camille
    Einride, Sweden.
    NPAD - Final Report D1.3: Network-RTK Positioning for Automated Driving2021Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Future automated vehicles and advanced driver assistance systems are highly dependent on sensors to detect their environment as well as robust, accurate, and cost-effective sensor systems for positioning. 

    Global Navigation Satellite systems (GNSS) provide a key technology that enables an absolute position estimate and Network-RTK (Real Time Kinematic) has the potential to meet the requirements of cost, accuracy, and availability. This technology is based on correction data being received from a fixed reference station via e.g. mobile communication. Current implementations have been driven by requirements from applications which operate within a limited region for lengthy periods of time, such as surveying and precision agriculture. These applications can tolerate relatively long initialization times and can afford expensive equipment.

    The mass market wants to benefit from infrastructure in place for these applications, but the requirements are somewhat different. Problems occur when the device moves from the coverage area of one reference station to another and reinitialization must be made. Consumer devices must also deliver similar performance with inexpensive components. In addition to this, the existing public-sector system for distribution of correction data, in Sweden governed by Lantmäteriet/ SWEPOS, is not designed for handling a large number of clients and efficiently distributing correction data to these clients based on their location.The telecom industry in 3GPP (Third generation partnership project) is currently addressing the need for a scalable provisioning of network RTK corrections. Based on the 3GPP specification, the project aimed to develop, implement, test and demonstrate an efficient distribution system for Network-RTK correction data in order to enable cm-level accuracy GNSS positioning for a large number of mobile platforms e.g. automated vehicles.

    The NPAD project has:

    • Leveraged the existing Lantmäteriet/SWEPOS GNSS reference infrastructure to implement a virtual network of reference stations that provided coverage over selected test areas suitable for supporting a large number of simultaneous users.
    • Implemented a scalable GNSS correction data provisioning based on the ongoing work in 3GPP that provides correction data from the reference network to mobile devices;
    • Developed test cases for automated vehicle platforms related to positioning and implemented demonstrators;
    • Investigated tools and methods for validating the accuracy of integrated GNSS positioning and navigation systems.

    The project was coordinated by RISE Research Institutes of Sweden and involved besides Lantmäteriet and AstaZero the following industrial partners: AB Volvo, Caliterra, Einride, Ericsson, Scania, and Waysure.

    Ladda ner fulltext (pdf)
    NPAD - D1.3 Final Report_v1.0
  • 19.
    Rieck, Carsten
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Gewies, Stephan
    German Aerospace Center, Germany.
    Grundhofer, Lars
    German Aerospace Center, Germany.
    Hoppe, Michael
    Federal Waterways and Shipping WSV, Germany.
    Synchronization of R-Mode Base Stations2020Ingår i: IFCS-ISAF 2020 - Joint Conference of the IEEE International Frequency Control Symposium and IEEE International Symposium on Applications of Ferroelectrics, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2020Konferensbidrag (Refereegranskat)
    Abstract [en]

    R-Mode is an alternative maritime PNT technology currently under development. It is based on synchronous transmissions and multilateration. Base station synchronization errors are recognized as the major error source. Introduction to R-Mode using maritime radio beacons, timing requirements, and the concept of R-Mode in-band synchronization are briefly presented.

  • 20.
    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 Data2010Ingår i: 6th IVS General Meeting, 2010, , s. 365-369Konferensbidrag (Övrigt vetenskapligt)
  • 21.
    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 Data2010Konferensbidrag (Övrigt vetenskapligt)
  • 22.
    Rieck, Carsten
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Jaldehag, Kenneth
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik. Chalmers University of Technology, Sweden.
    A hardware accelerated 10GbE primary NTP-server2012Ingår i: European Frequency and Time Forum, EFTF 2012, 2012, , s. 387-391s. 387-391, artikel-id 6502408Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present a primary NTP server design that provides a full line rate packet stream handling with about 50 ns internal timing accuracy independent from packet throughput. The provided solution is replay proof and is intended for NTP services close to backbone of the Internet.

  • 23.
    Rieck, Carsten
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik. Chalmers University of Technology, Sweden.
    Jaldehag, Kenneth
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Time transfer with nanosecond accuracy using ethernet2014Ingår i: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI, Institute of Electrical and Electronics Engineers Inc. , 2014, s. 74-78Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hardware aided time stamping of Ethernet frames is used to implement a two way time transfer. The method is capable to either operate actively by initiating or relaying frames, or passively by utilization the traffic on, preferably, optical links. Time stability of unfiltered measurements taken on local links is about 3.5 ns @ 1s TDEV, reaching below 1 ns for time intervals of about 100s. The presented method is specific to a family of commercial traffic analyzers, but can be generalized for any similar capable hardware.

  • 24.
    Rieck, Carsten
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Jaldehag, Kenneth
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Ebenhag, Sven-Christian
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Jarlemark, Per
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Hedekvist, Per Olof
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Time and frequency laboratory activities at RISE2020Ingår i: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI, Institute of Electrical and Electronics Engineers Inc. , 2020, s. 169-180Konferensbidrag (Refereegranskat)
    Abstract [en]

    RISE Research Institutes of Sweden is since 2018 the result of a rebranding of SP Technical Research Institute of Sweden and several other national research facilities and test beds in Sweden. This also comprises most national metrology institute (NMI) activities, including time and frequency that is still located at its Borås facilities in the southwest of Sweden since 1995. UTC(SP) remains the official designation of the Swedish UTC(k) realization. It is realized in a classical master clock and phase stepper setup and is locally distributed to different users and time transfer applications. The most recent local clock ensemble consists of four hydrogen masers and three high performance 5071A Cs standards. UTC(SP) is linked to TAI using TWSTFT and GNSS. The primary link is a combination TWGPPP with current calibration uncertainties of 1.1 ns. The time scale is regularly kept within ±5 ns of UTC. RISE has also established several distributed UTC(SP) copies, with both local backups in Borås and facilities at remote sites linked together by GNSS time transfer. Network time distribution at those sites make UTC(SP) publicly available. Additionally, RISE offers several calibration services for the distribution of UTC-traceable time and frequency signals. Time and frequency related metrological research at RISE is mostly concentrated on further refinement of GNSS and TWSTFT methods, their calibration and the dissemination using those methods. We are also active in research on fiber based optical time and frequency transfer. Outside the metrological responsibilities, many research projects focus on establishing metrological aspects of time and frequency within for instance the automotive and maritime domain.

  • 25.
    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 CONT112012Ingår i: European Frequency and Time Forum (EFTF 2012), 2012, , s. 163-165s. 163-165, artikel-id 6502358Konferensbidrag (Refereegranskat)
    Abstract [en]

    Geodetic VLBI is an independent technique, which does not rely on third parties. This makes it a viable future alternative for time- and frequency transfer over long baselines. Frequency link instabilities in the order of 1.5e-15 for time periods of one day are comparable to those achievable with methods using GNSS carrier-phase observations. Data of the continuous VLBI campaign CONT11 were analyzed and compared to results from GPS PPP analysis on collocated/common clock stations.

  • 26.
    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 Campaigns2012Ingår i: IVS 2012 General Meeting Proceedings, 2012, , s. 425-429Konferensbidrag (Övrigt vetenskapligt)
  • 27.
    Rieck, Carsten
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Jarlemark, Per
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Jaldehag, Kenneth
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Passive utilization of the TWSTFT technique2018Konferensbidrag (Refereegranskat)
    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.

  • 28.
    Rieck, Carsten
    et al.
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Jarlemark, Per
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Nord, Stefan
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Alissa, S.
    Swedish Land Survey, Sweden.
    Gunnarsson, F.
    Ericsson Research, Sweden.
    Harmonization of NPRS observations for a seamless RTK positioning service in automated driving applications2021Ingår i: Proceedings of the 34th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS+ 2021, Institute of Navigation , 2021, s. 402-423Konferensbidrag (Refereegranskat)
  • 29.
    Rieck, Carsten
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Jarlemark, Per O.J.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Jaldehag, Kenneth
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Mätteknik.
    Utilizing TWSTFT in a passive configuration2017Ingår i: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI, Institute of Electrical and Electronics Engineers Inc. , 2017, s. 219-234Konferensbidrag (Refereegranskat)
    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.

  • 30.
    Svensson, Stefan
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Rieck, Carsten
    RISE - Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Bideberg, Glenn
    RISE - Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Larsson, Bo
    RISE - Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    A PMU Calibration System2018Ingår i: CPEM 2018 - Conference on Precision Electromagnetic Measurements, 2018Konferensbidrag (Refereegranskat)
    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 - 30 av 30
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf