Research On Techniques For High-accuracy Time Interval Measurement

Time interval measurement is the measurement basis of many physical variables such as period, frequency and phase. With the development of science and technology, the frequency of the signal under measurement raises rapidly, which makes the further research on the time interval measurement necessary. The research aims at improving the resolution and speed of time interval measurement. so the improvement of time interval measurement can accelerate the development in these fields and promote the development of economy.In this paper, we design a kind of time interval measurement method based on phase coincidence detection envelope. We design and implement a short time interval measurement system based on phase coincidence detection. This method not only ensures high resolution and high precision of the measurement but also enlarges the measuring scope, simplifies the system structure, and greatly reduces the power consumption of the system. According to the phase relationship between the periodic signals, we deeply analyse quantitative phase of the periodic signal,and summarize the law of the phase relationship between the periodic signals. After analysis of the formation of phase coincidence detection and its envelope, we relate time interval measurement and phase coincidence detection because of the high stability of the phase coincidence detection of the envelope and phase quantization. In order to improve the resolution of the time interval measurement system, the experiment to verify the phase coincidence and carries on the error of quantitative analysis have been did. Verified by experiments, the application of a phase coincidence detection envelope on time interval measurement can achieve highaccuracy time interval measurement. In this paper, we use FPGA implement phase coincidence detection circuit and the signal conditioning circuit in the time interval measurement system, it realizes the output of the phase coincidence detection envelope and data collection.Measurement system function and resolution of the system are verified based on phase coincidence detection envelope method and changing signal size under test. Test results show that the actual measuring resolution of the time interval measurement system in this paper can be up to 70 ps.