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Rieck, C., Jaldehag, K., Ebenhag, S.-C., Jarlemark, P. & Hedekvist, P. O. (2020). Time and frequency laboratory activities at RISE. In: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI: . Paper presented at 51st Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI 2020, 21 January 2020 through 24 January 2020 (pp. 169-180). Institute of Electrical and Electronics Engineers Inc.
Öppna denna publikation i ny flik eller fönster >>Time and frequency laboratory activities at RISE
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2020 (Engelska)Ingår 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, Publicerat paper (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.

Ort, förlag, år, upplaga, sidor
Institute of Electrical and Electronics Engineers Inc., 2020
Nyckelord
Clocks, Hydrogen masers, Time measurement, Calibration uncertainty, National metrology institutes, Research facilities, Research institutes, Technical research, Time and frequencies, Time and frequency transfers, Time distribution, Calibration
Nationell ämneskategori
Naturvetenskap
Identifikatorer
urn:nbn:se:ri:diva-44903 (URN)10.33012/2020.17297 (DOI)2-s2.0-85081552388 (Scopus ID)0936406259 (ISBN)
Konferens
51st Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI 2020, 21 January 2020 through 24 January 2020
Anmärkning

Funding details: National Measurement Institute, NMI; Funding details: VINNOVA; Funding text 1: RISE has inherited the function of the Swedish NMI from SP Technical Research Institute of Sweden in 2018 when the RISE institutes Innventia, Swerea, SP and Swedish ICT merged to create a stronger research and innovation partner for businesses and society. The intention is to make industrial research institutes internationally more competitive and to facilitate continued sustainable growth in Sweden by strengthening competitiveness and renewal in the business community [1]. RISE is appointed as the Swedish NMI by the Ministry of Enterprise and Innovation. The NMI is funded from Vinnova [2], Sweden’s innovation agency and any strategic decisions are made by an advisory board composed of experts from Swedish industry. Vinnova decides the level of NMI funding and also the Swedish level of participation in European funded research of the EMPIR program and its possible successor.; Funding text 2: This report was supported by the Swedish National Metrology Program, program owner Swedish Agency for Innovation Systems (VINNOVA). We acknowledge the work of the BIPM, the CCTF and EURAMET, further the Swedish Post and Telecom Authority (PTS) who finances critical Swedish communication infrastructure and thereby strengthens resiliency in national timing.

Tillgänglig från: 2020-05-20 Skapad: 2020-05-20 Senast uppdaterad: 2023-06-08Bibliografiskt granskad
Jaldehag, K., Jarlemark, P. & Rieck, C. (2019). Further Evaluation of CGGTTS Time Transfer Software. In: IFCS/EFTF 2019 - Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum, Proceedings: . Paper presented at 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum, IFCS/EFTF 2019, 14 April 2019 through 18 April 2019. Institute of Electrical and Electronics Engineers Inc.
Öppna denna publikation i ny flik eller fönster >>Further Evaluation of CGGTTS Time Transfer Software
2019 (Engelska)Ingår 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, Publicerat paper (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. 

Ort, förlag, år, upplaga, sidor
Institute of Electrical and Electronics Engineers Inc., 2019
Nyckelord
CGGTTS, GNSS, Software, Time Transfer, Codes (symbols), Computer software, Global positioning system, Petroleum reservoir evaluation, Radio navigation, Linear combinations, Research institutes, Satellite navigation systems, Stand-alone software, Time and frequencies, Application programs
Nationell ämneskategori
Naturvetenskap
Identifikatorer
urn:nbn:se:ri:diva-40615 (URN)10.1109/FCS.2019.8856022 (DOI)2-s2.0-85073778760 (Scopus ID)9781538683057 (ISBN)
Konferens
2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum, IFCS/EFTF 2019, 14 April 2019 through 18 April 2019
Tillgänglig från: 2019-11-26 Skapad: 2019-11-26 Senast uppdaterad: 2023-05-23Bibliografiskt granskad
Jaldehag, K., Rieck, C. & Jarlemark, P. (2018). Evaluation of CGGTTS time transfer software using multiple GNSS constellations. In: : . Paper presented at 2018 European Frequency and Time Forum (EFTF) (pp. 159-166).
Öppna denna publikation i ny flik eller fönster >>Evaluation of CGGTTS time transfer software using multiple GNSS constellations
2018 (Engelska)Konferensbidrag, Publicerat paper (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.

Nyckelord
Global navigation satellite system, Global Positioning System, Receivers, Satellites, Software tools, Standards, GNSS, Time Transfer, CGGTTS, Software, IGS
Nationell ämneskategori
Naturvetenskap
Identifikatorer
urn:nbn:se:ri:diva-34325 (URN)10.1109/EFTF.2018.8409022 (DOI)2-s2.0-85050763645 (Scopus ID)
Konferens
2018 European Frequency and Time Forum (EFTF)
Tillgänglig från: 2018-08-07 Skapad: 2018-08-07 Senast uppdaterad: 2023-05-23Bibliografiskt granskad
Rieck, C., Jarlemark, P. & Jaldehag, K. (2018). Passive utilization of the TWSTFT technique. In: : . Paper presented at 2018 European Frequency and Time Forum (EFTF) (pp. 263-269).
Öppna denna publikation i ny flik eller fönster >>Passive utilization of the TWSTFT technique
2018 (Engelska)Konferensbidrag, Publicerat paper (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.

Nyckelord
Orbits, Extraterrestrial measurements, Delays, Satellites, Real-time systems, Atmospheric measurements, Current measurement, TWSTFT, time transfer, orbit determination, passive approach, real-time, resiliency
Nationell ämneskategori
Naturvetenskap
Identifikatorer
urn:nbn:se:ri:diva-34326 (URN)10.1109/EFTF.2018.8409046 (DOI)2-s2.0-85050723601 (Scopus ID)
Konferens
2018 European Frequency and Time Forum (EFTF)
Tillgänglig från: 2018-08-07 Skapad: 2018-08-07 Senast uppdaterad: 2023-05-23Bibliografiskt granskad
Rieck, C., Jarlemark, P. O. .. & Jaldehag, K. (2017). Utilizing TWSTFT in a passive configuration. In: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI: . Paper presented at Precise Time and Time Interval Systems and Applications Meeting, PTTI 2017, 30 January 2017 through 2 February 2017 (pp. 219-234). Institute of Electrical and Electronics Engineers Inc.
Öppna denna publikation i ny flik eller fönster >>Utilizing TWSTFT in a passive configuration
2017 (Engelska)Ingår 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, Publicerat paper (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.

Ort, förlag, år, upplaga, sidor
Institute of Electrical and Electronics Engineers Inc., 2017
Nyckelord
Orbits, Satellites, Time measurement, Correction models, European networks, Local coordinate, Position estimates, Residual range, Satellite ephemeris, Satellite position, Two-way satellite time and frequency transfers, Tracking (position)
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ri:diva-38134 (URN)10.33012/2017.15002 (DOI)2-s2.0-85047020426 (Scopus ID)9781510855397 (ISBN)
Konferens
Precise Time and Time Interval Systems and Applications Meeting, PTTI 2017, 30 January 2017 through 2 February 2017
Tillgänglig från: 2019-03-04 Skapad: 2019-03-04 Senast uppdaterad: 2023-05-23Bibliografiskt granskad
Jaldehag, K., Jarlemark, P. & Rieck, C. (2016). Clock models for Kalman filtering.
Öppna denna publikation i ny flik eller fönster >>Clock models for Kalman filtering
2016 (Engelska)Rapport (Övrigt vetenskapligt)
Serie
SP Rapport, ISSN 0284-5172 ; 2016:48
Nationell ämneskategori
Naturvetenskap
Identifikatorer
urn:nbn:se:ri:diva-623 (URN)
Tillgänglig från: 2016-06-29 Skapad: 2016-06-29 Senast uppdaterad: 2023-05-23Bibliografiskt granskad
Bideberg, G., Ebenhag, S.-C., Jaldehag, K. & Hedekvist, P. O. (2014). Construction of a secure clock location for alternative realization of UTC(SP). In: 2014 European Frequency and Time Forum (EFTF): . Paper presented at 28th European Frequency and Time Forum (EFTF 2014), June 23-26, 2014, Neuchatel, Switzerland (pp. 498-501). , Article ID 7331545.
Öppna denna publikation i ny flik eller fönster >>Construction of a secure clock location for alternative realization of UTC(SP)
2014 (Engelska)Ingår i: 2014 European Frequency and Time Forum (EFTF), 2014, s. 498-501, artikel-id 7331545Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Swedish standard time is regulated by law to follow UTC as maintained by the BIPM. The atomic clocks that are used to implement UTC(SP), the realization of UTC in Sweden, are located at four different sites and are reported to TAI using data from TWSTFT and GNSS links. The activities in the Time and Frequency laboratory at SP are presently undergoing an expansion with the construction of a new additional secure site and the implementation of a distributed time scale.

Nyckelord
Distributed timescale, NMI, UTC, UTC(SP), Distributed time, Standard time, Swedishs, Time and frequencies, Time-scales
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ri:diva-38525 (URN)10.1109/EFTF.2014.7331545 (DOI)2-s2.0-84971383871 (Scopus ID)978-1-4799-5252-6 (ISBN)
Konferens
28th European Frequency and Time Forum (EFTF 2014), June 23-26, 2014, Neuchatel, Switzerland
Tillgänglig från: 2019-05-06 Skapad: 2019-05-06 Senast uppdaterad: 2023-06-08Bibliografiskt granskad
Hedekvist, P. O., Rieck, C., Jaldehag, K. & Backefeldt, J. (2014). Experimental data from NTP-monitoring and uncertainty estimation in nationwide network. In: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI: . Paper presented at 46th Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI 2014, 1 December 2014 through 4 December 2014 (pp. 52-56). Institute of Electrical and Electronics Engineers Inc.
Öppna denna publikation i ny flik eller fönster >>Experimental data from NTP-monitoring and uncertainty estimation in nationwide network
2014 (Engelska)Ingår 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, Publicerat paper (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.

Ort, förlag, år, upplaga, sidor
Institute of Electrical and Electronics Engineers Inc., 2014
Nyckelord
Bandwidth, Packet networks, Platinum alloys, Traffic congestion, Virtual private networks, Back-bone network, Daily variations, Independent measurement, Local oscillators, National timescale, Network improvement, Network time protocol, Uncertainty estimation, Uncertainty analysis
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ri:diva-47286 (URN)2-s2.0-84943233527 (Scopus ID)9781634397940 (ISBN)
Konferens
46th Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI 2014, 1 December 2014 through 4 December 2014
Tillgänglig från: 2020-08-26 Skapad: 2020-08-26 Senast uppdaterad: 2023-06-05Bibliografiskt granskad
Rieck, C. & Jaldehag, K. (2014). Time transfer with nanosecond accuracy using ethernet. In: Proceedings of the Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI: . Paper presented at 46th Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI 2014, 1 December 2014 through 4 December 2014 (pp. 74-78). Institute of Electrical and Electronics Engineers Inc.
Öppna denna publikation i ny flik eller fönster >>Time transfer with nanosecond accuracy using ethernet
2014 (Engelska)Ingår 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, Publicerat paper (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.

Ort, förlag, år, upplaga, sidor
Institute of Electrical and Electronics Engineers Inc., 2014
Nyckelord
Hardware, Platinum alloys, Commercial traffic, Ethernet frames, Time interval, Time stability, Time transfer, Timestamping, Two-way time transfers, Ethernet
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ri:diva-45558 (URN)2-s2.0-84943569490 (Scopus ID)9781634397940 (ISBN)
Konferens
46th Annual Precise Time and Time Interval Systems and Applications Meeting, PTTI 2014, 1 December 2014 through 4 December 2014
Anmärkning

Conference code: 114335

Tillgänglig från: 2020-08-10 Skapad: 2020-08-10 Senast uppdaterad: 2023-05-23Bibliografiskt granskad
Hedekvist, P. O., Jaldehag, K., Ebenhag, S.-C., Rieck, C., Bideberg, G. & Jaldehag, K. (2013). Time and Frequency Activities at SP. In: : . Paper presented at Proceedings of the 45th Annual Precise Time and Time Interval Systems and Applications Meeting, December 2 - 5, 2013, Hyatt Regency Bellevue, Bellevue, Washington (pp. 21-25).
Öppna denna publikation i ny flik eller fönster >>Time and Frequency Activities at SP
Visa övriga...
2013 (Engelska)Konferensbidrag, Publicerat paper (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.

Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:ri:diva-38800 (URN)
Konferens
Proceedings of the 45th Annual Precise Time and Time Interval Systems and Applications Meeting, December 2 - 5, 2013, Hyatt Regency Bellevue, Bellevue, Washington
Tillgänglig från: 2019-05-14 Skapad: 2019-05-14 Senast uppdaterad: 2023-06-08Bibliografiskt granskad
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0002-5518-4607

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