A Study on the EURAMET Comparison of Time Interval Measurement

At April 2003 there were 25 National Metrology Institutes in 25 countries that are members in the European Association of National Metrology Institutes (EURAMETs) agreed to participate in an inter-laboratory comparison for time interval measurement (TIM). The main target of this comparison, as mentioned by EURAMET, was to support the current calibration measurement capabilities for TI and to gain better understanding of the TIM. Cable delay measurement was taken as an example. The time delay of three different length coaxial cables (short, medium, and long) was measured. The majority of the laboratories used the Counter Method. There was a large span between the measurements for all cables (about 1 ns). Consequently, the measurement results that had been published at 2007 were not satisfied for the participant laboratories. In this article, we study the probable reasons for this considerable span between the different measurements for the same artifact.