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A system for distributing high-speed synchronous high-precision clock and trigger data over large distances
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2008 (English)Conference paper (Refereed)
Abstract [en]

The distribution of precise timing throughout the European X-ray Free Electron Laser project [1] (XFEL) and its triggering system is a very challenging part of the system design. ADCs in data acquisition systems and DACs in control systems will require very high precision clocks. The clocks need to be synchronous to each other, both in frequency and phase, with a jitter performance better than 5 ps (RMS). At some high-speed ADCs it might even need a precision down to 0.1 ps. The frequencies that must be available are the main 1.3 GHz and some frequencies below, which are all derived from the main frequency. The phase needs to be adjustable to allow synchronization between separate devices. Triggering information needs to be distributed over the system, so that controlling instructions can be carried out at a very precise time. This is very important since the beam will travel with the speed of light, and there is no possibility for information to be sent back and forth. This requires an absolute timing to be distributed over the system. Both the main clock and triggering information will be transmitted over the same fiber cable, one to each device. An advanced synchronization method needs to be developed to synchronize the phases of the clocks throughout the whole system. The delay through the cable can change with temperature, and due to long cables the total change through a single cable can be significant. It is essential that the clocks are stable and not drifting away from each other. Therefore a continuous calibration method is needed, ensuring that the clocks are synchronous throughout the whole system. A prototype of such a system is being developed and a first version is expected to be completed in 2009 Ql.

Place, publisher, year, edition, pages
2008. 2581-2584 p.
, IEEE Nuclear Science Symposium Conference Record, ISSN 1095-7863
Keyword [en]
Absolute timing, Calibration method, Data acquisition system, Fiber cables, High precision, High-speed, Information need, Jitter performance, Main frequency, Separate devices, Speed of light, Synchronization method, System design, Triggering systems, Whole systems, X-ray free electron lasers, Cables, Free electron lasers, Jitter, Lasers, Time measurement, Clocks
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-154121DOI: 10.1109/NSSMIC.2008.4774885ScopusID: 2-s2.0-67649183181ISBN: 9781424427154OAI: diva2:758012
2008 IEEE Nuclear Science Symposium Conference Record, NSS/MIC 2008; Dresden; Germany; 19 October 2008 through 25 October 2008

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Available from: 2014-10-24 Created: 2014-10-14 Last updated: 2014-10-24Bibliographically approved

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Rydström, Stefan
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