A Time Interval Measurement Technique Based On TDC Method

This paper studies a new time interval measurement method using TDC(time-to-digital converter) to measure time intervals in combination with counter. Themethod enlarges the measurement scope and the structure is simplified while ensuringhigh resolution and precision. In addition, system power dissipation is also significantlydecreased.The time intervals we measured can be divided into two sections: clocksynchronized part and clock unsynchronized part. Because the speed of electrical signaltransmitted in a vacuum is a constant of nature, it has high speed and high stability. Weused the same specific path of active device as a standard to quantify the clockunsynchronized part of the time intervals, so the resolution and precision of timeinterval measurement is improved and the ? 1counting error is also decreased. Thetime-gate is constituted by the start and stop signals of the time interval and the delayunits is used to quantify the clock unsynchronized part of the time intervals. In this way,time variable is converted into digital variable that is clock counting value and phasedifference quantification value. The schematic diagram of time interval measurementsystem is given in this paper. We established system model and analyzed the errorsource and correction method.We have designed a time interval measurement system based on TDC atEP1C6T144I7 of Cyclone series, which utilized delay unites Lcell of active devices toconstitute the specific transmission path. The prototype machine according to thismethod can reach to a solution of 180ps in practical measurement and the measurementscope can reach to 43s approximately. We have designed the time synchronizationsystem on the basis of time interval measurement system. Practice shows that theresolution of the time synchronization system can reach to 1ns.