| 1. |
- Ebenhag, Sven-Christian, 1976, et al.
(författare)
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Time Transfer between UTC(SP) and UTC(MIKE) Using Frame Detection in Fiber-Optical Communication networks
- 2011
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Ingår i: 43rd Precise Time and Time Interval (PTTI) Systems and Applications Meeting. - 9781622767953 ; , s. 431-441
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Konferensbidrag (refereegranskat)abstract
- This paper presents recent results from a time transfer method using passive listening and detection of SDH frame headers in fiber-optical networks. The results are based on an experimental fiber-link that is implemented between the national time and frequency laboratories at SP in Borås, Sweden and at MIKES in Espoo, Finland with an intermediate connection at STUPI time and frequency facility in Stockholm, Sweden. The total fiber length exceeds 1129 km and is implemented in SUNET (Swedish University Network) and FUNET (Finnish University and Research Network). The two networks are connected via NORDUnet (Nordic Infrastructure for Research & Education) and the links are DWDM-based (Dense Wavelength Division Multiplexing).Both SP and MIKES maintains local representations of UTC and contributes with clock data to TAI, which gives the opportunity to compare the fiber-based method with those independent methods that are used regularly by the laboratories for the links to UTC. Preliminary results show that a time transfer stability of less than 10 picoseconds is obtained for averaging times of a few hundred seconds. The results also show that the method suffers from daily variations of a few nanoseconds, presumable due to temperature sensitive network equipment and asymmetric fiber paths. Nevertheless, a comparison to GPS carrier phase time transfer over three months shows an rms-agreement of less than 1 nanosecond.
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| 2. |
- Jaldehag, R. T. Kenneth, 1962, et al.
(författare)
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Time Transfer Using Frame Detection in Fiber-Optical Communication Networks: New Hardware
- 2011
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Ingår i: Frequency Control and the European Frequency and Time Forum (FCS), Joint Conference of the IEEE International.
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Konferensbidrag (refereegranskat)abstract
- In this paper, a new, recently developed hardware for time transfer using passive listening and detection of SDH frame headers in fiber-optical networks is described. The method has been presented earlier, and results, using prototype equipment and an experimental fiber-link, have shown that time transfer with a precision of the order of a few nanoseconds is possible over links with network distances exceeding 500 km. In order to further develop the method and make it available to regular users of time keeping equipment, it has been essential to minimize the space requirements of needed hardware and to make the implementation and installation more easily and straight forward. The new hardware is in this paper described in detail.
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