National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Event Timing Device Providing Subpicosecond Precision
Pánek, Petr ; Kodet, J. ; Procházka, I.
We are reporting on the latest experimental results achieved with an event timing device using a surface acoustic wave filter as a time interpolator. During the tests of the first version of the device, the noise of the filter excitation was identified as the dominant source of the measurement error. Therefore a new concept of the excitation with very low level of the noise energy was designed. This new solution led to considerable improvement of the device performance. It results from the experimental measurements that the single shot precision is repeatedly lower than 500 fs RMS when time marks generated synchronously with the time base are measured. When asynchronous time marks are split into two event timers and the resulting time difference is measured, the single shot precision is below 700 fs RMS per channel. In this case the measurement is affected not only by random errors, but also by non-linearity of the time interpolation. The temperature dependence is below 0.1 ps/K. Operating the device in a common laboratory environment without temperature stabilization, the stability TDEV better than 3 fs has been routinely achieved for range of averaging intervals from 10 s to several hours
Local ties controlin application of laser time transfer
Kodet, J. ; Schreiber, U. ; Eckl, J. ; Procházka, I. ; Pánek, Petr
In many fundamental physical experiments time plays an important role. The standard way for the comparison of time and frequency is the application of GNSS signals and the Two-Way Satellite Time and Frequency Transfer - TWSTFT. This technique is based on radiofrequency signal transmission. Recently, there was a rapid increase of optical time comparison development, which uses the Satellite Laser Ranging network (SLR). Currently the French project T2L2 is in operation on board of Jason 2 and the European Space Agency project ELT in support of the Atomic Clock Ensemble in Space (ACES) is under development. The goal of both projects is the time synchronization with a precision below 40 ps rms and an absolute error well below 100 ps. Comparing the results of the optical time transfer with the GNSS time comparison requires unprecedented control of the local ties between the different observation techniques. One of the possible methods is the application of the Two Way Time Transfer (TWTT) on a single coaxial cable. Such a system can be implemented using two or more event timers, which are interconnected by a standard coaxial cable.

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