Pilot study: Time interval comparison

Project Description

In 2007 the EUROMET TF.TI-K1 Comparison of time interval (cable delay) measurement was completed and the final report was issued by BEV. The main goal of that project was to The main conclusion was: The EURAMET 828 project showed that the transmission delay of any signal through a cable depends on several parameters and does not well define a measurement quantity “time interval” and we should be more aware of the fact that the value of a “cable delay”, even for the same cable, is not a fundamental constant. The project results did not immediately support the (then) defined T&F Key Comparison and it was not considered as a Supplementary Comparison. It is believed that a successful ILC on time interval is nevertheless possible, with the goal to support current CMCs for time interval and to gain better understanding of the time interval measurement through cable delay or other measurement techniques. For that, we need first to implement a successful Pilot Study.

In the proposed Pilot Study project, a different traveling standards for time interval comparison will be studied and prepared and cable box as provided from BEV will be investigated again. Necessary measurements on these travelling standards will be performed by Pilot Study participants. The Inter-Laboratory Comparison (ILC) Protocol (and especially measurement parameters and methods) will be correctly defined so as to enable to launch a EURAMET TF.TI-K2 to serve as an EURAMET Supplementary comparison.

The proposed activities are:

Study and build of new transfer standard(s)
Study on using existing cable box
Performing verification measurements
Preparation of detailed and harmonised ILC Protocol.

Previous ILC (EURAMET TF.TI-K1) was performed under the EURAMET Project 828 "EUROMET supplementary comparison TF.TI-K1 Comparison of time interval (cable delay) measurement".

Final Report 2019-03-04

For the time interval comparison pilot study, two new measurement standards were developed and characterised:
1. TIGen – Time Interval Generator based on PLL loops and programmable logic and counters was developed by AGH-GUM. It requires external 10 MHz signal and can generate 127 different time intervals from about 20 ns to 12 μs with < 1 ps quasi long-term stability.
2. InLambda standards based on temperature stabilized delay of fibers, developed by InLambda company. They can generate three time intervals of roughly 20 ns, 100 ns and 300 ns with < 2 ps quasy long-term stability.
Both standards were thoroughly tested for all influential parameters. They were further fine tuned for best stability. InLambda standard showed worse performance, which could be compensated by operating within more strich parameters.TIGen was successfully characterised by AGH, NIT, UME, SASO and SIQ between June 2015 and March 2016 with high speed oscilloscopes.
The proposed method of calculation of the reference value was prepared. The work was published at EFTF 2016 as "Pilot Comparison of Time Interval Measurements with High Speed Oscilloscopes – initial results" by Albin Czubla, Piotr Szterk, Przemysław Krehlik, Łukasz Śliwczyński, Mesut Yogun, Ramiz Hamid, Khaled AlDawood, Fahad Almuhlaki, Ahmed Aljawan, Ibrahim Alboraih, Borut Pinter, Michał Marszalec and Marzenna Lusawa.
The Supplementary Comparison in Time Interval measurements will be proposed based on this Pilot Study.

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