A Novel Method with Ps Accuracy for Time Interval Measurement

High precise time interval measurement is widely used in time synchronization, satellite navigation, aerospace tracking telemetering, laser metering and nuclear electronics. The resolution and accuracy of the current used time counter is 25 ps and nearly 100 ps, respectively. A new time interval measurement method was put forward, in which, the signal under test is used to trigger a sampler and the phase of the reference sine signal sampled record the time stamp of the test signal. The sampled reference sine signal's phase is estimated by interpolated FFT and 1 ps resolution and accuracy can be achieved theoretically. The test experiment of prototype instrument show 10 ps accuracy has been achieved. If the hardware prototype is improved to reduce trigger jitter and sampling clock jitter, the measurement instrument may reach 1ps accuracy. The measurement system is used not only time interval measurement, but also for period measurement and modulation domain analysis.