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- Bergstrand, Sten, 1971, et al.
(author)
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Ionospheric Corrections for Accurate Positioning in Real Time
- 2005
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In: in Proc. Radio Science and Communication (RVK), eds. O. Gustafsson, P. Löwenborg, Linköping, Sweden, June 14-16, 2005. - 9170561222 ; , s. 391-394
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Conference paper (other academic/artistic)
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- Ebenhag, Sven-Christian, 1976, et al.
(author)
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Measurements and Error Sources in Time Transfer Using Asynchronous Fiber Network
- 2010
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In: IEEE Transactions on Instrumentation and Measurement. - 1557-9662 .- 0018-9456. ; 59:7, s. 1918-1924
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Journal article (peer-reviewed)abstract
- We have performed time transfer experiments basedon passive listening in fiber optical networks using Packet over synchronous optical networking (SONET)/synchronous digital hierarchy(SDH). The experiments have been performed with differentcomplexity and over different distances. For assessmentof the results, we have used a GPS link based on carrier-phase observations. On a 560-km link, precision that is relative to the GPS link of
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| 6. |
- Ebenhag, Sven-Christian, 1976, et al.
(author)
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Time Transfer over a 560 km Fiber Link
- 2008
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In: EFTF 2008 - 22nd European Frequency and Time Forum. ; , s. Paper E5A04 -
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Conference paper (peer-reviewed)
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| 7. |
- Ebenhag, Sven-Christian, 1976, et al.
(author)
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Time transfer using an asynchronous computer network: An analysis of error sources
- 2007
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In: European Frequency and Time Forum, 29/5 - 1/6, Geneva, CH.
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Conference paper (peer-reviewed)abstract
- We have performed a time transfer over a distance ofapproximately 75 km using an asynchronous computer networkbased on optical fibers. In order to validate the results from thisfiber-link, we have compared the results with a GPS-link, whichconsists of carrier phase observations. All electronic cabinetswere equipped with temperature and humidity sensors. Here wepresent experiments where the temperature and humidity of thedelay in the electrical components were investigated. Allcomponents showed some temperature dependence, but nosignificant humidity dependence was found. By using thederived temperature coefficient for the components the standarddeviation of the difference between the fiber link and GPS linkdecreased from 243ps to184ps.
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| 8. |
- Ebenhag, Sven-Christian, 1976, et al.
(author)
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TIME TRANSFER USING AN ASYNCHRONOUS COMPUTER NETWORK: RESULTS FROM A 500 KM BASELINE EXPERIMENT
- 2007
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In: Topical Meeting on Precise Time and Time Interval, 27-30/11, Long Beach, CA.
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Conference paper (peer-reviewed)abstract
- SP Technical Research Institute of Sweden and STUPI have performed a time transferexperiment over a 500km long baseline between Borås and Stockholm. The time transfertechnique passively utilizes the data bit stream generated in an optical fiber computer networkbased on the packet over SONET/SDH technique. A small fraction of the optical signal ismonitored both at the transmitter and at the receiver. When an occurrence of a unique bitsequence of the SDH frames is detected, an electrical pulse is generated and compared with aresolution of 100 ps to a local clock. With data from all four positions of an optical bidirectionallink, two-way time-transfer can be achieved and any symmetrical variations in delay canpotentially be cancelled. The results presented here have been obtained over OptoSUNET, thenew Swedish University Network. In the experiment, 10 Gbit/s traffic from SP over OptoSUNETis extended in Stockholm to STUPI, a clock laboratory which is the second node in this setup.This reconnection enables that a communication channel is established between two nodes,with no intermediate jump. The time-transfer experiment includes more than 500 km of fibertransmission, of which several km is via air-lines. By comparing the results from a GPS carrierphaselink, a precision better than ± 1 ns is achieved over several months of measurementsbetween two Hydrogen-masers.
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| 9. |
- Ebenhag, Sven-Christian, 1976, et al.
(author)
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Time transfer using an asynchronous computer network: Results from three weeks of measurements
- 2007
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In: European Frequency and Time Forum, 29/5 - 1/6, Geneva, CH.
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Conference paper (peer-reviewed)abstract
- We have performed a time transfer experimentbetween two atomic clocks, over a distance of approximately 75km using an 10 Gbit/s asynchronous fiber-optic computernetwork. The time transfer was accomplished through passivelistening on existing data traffic and a pilot sequence in the SDHbit stream. In order to assess the fiber-link clock comparison, wesimultaneously compared the clocks using a GPS carrier phaselink. The standard deviation of the difference between the twotime transfer links over the three-week time period was 243 ps.
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