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13th International Laser Ranging Workshop
"Toward Millimeter Accuracy"

Timing Devices (E. Samain and P. Gibbs)
Session Summary

Title Primary Author
ILRS Timing Devices: Specifications, Error Analysis, BEST Calibration Practices Van Husson
Range comparison results for various Eurolas SR timers Philip Gibbs
Counter Calibrations at Zimmerwald Werner Gurtner
A010 Family of Time interval Counters Adapted to SLR Applications Yuri Artyukh
An ultra stable event timer Etienne Samain
Operational Performance of GPS Steered Rubidium Oscillators Loyal Stewart

The central theme of the session was based on possible biases from SR620 timers and the development of new timers. Users of SR620 timers were encouraged to calibrate their timers against other timers.

Van Husson gave an overview of the various timing devices within the SLR network, which is split almost evenly at 1/3 rd HP timers, 1/3 rd SR620 timers and 1/3 rd event timers. Best practices for the various timing devices were discussed – a poster for SR620 best practices will appear shortly on the web through the ILRS website. Stability plots shown hinted that systems using event timers were producing the most stable results.

Philip Gibbs and Werner Gurtner gave papers showing results of comparisons for clusters of mainly SR timers. PG showed the results of the many tests carried out at Herstmonceux of 8 SRs, 3HPs and PPET against a single SR timer (Hx-D). The results showed that SR timers have biases of between 0ps and 100ps. These biases would appear to be very stable over many years. WG showed the results of comparisons carried out at Zimmerwald, highlighting the problems encountered when using 5MHz instead of 10Mhz. Both Herstmonceux and Zimmerwald are now giving their results on the Hx-D system (which is equivalent to PPET system).

Kazimirs Lapushka and Etienne Samain gave papers on new timers currently under development. KL Gave details of the latest in the A010 family of PC based interval counters and gave details of improvements on previous models. The system is based on a single channel for start and stop as using the same hardware configuration gives high linearity and temporal stability. The resolution is better than 10ps. ES presented the new timer under development at OCA. It has a vernier with a resolution of 1ps, an ultra stable 100MHz, a calibration module for long-term stability and a digital module for the counter, the memory, the phase lock loop and serial interface. Results so far show a precision better than 3ps, time stability below 10fs/1000secs, linearity of 1ps and thermal sensitivity of 0.5ps/oC.

The session ended with a poster paper by Loyal Stewart on the GPS steered Rubidium Oscillator now being used by the NASA SLR network as a time and frequency standard.


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Responsible NASA Official: Ed Grayzeck
Last Updated: June 17, 2014



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