Frequency And Time Measurement Method And Study Based On Passive And Active Delay Chain

In recent years, frequency and time measurement method based on the relationship of time-space for its simple measurement system simple and high-precision has a lot of attention. Basing the principle of time-delay quantitative and using the delay chain, this method can reduce the count error of±1 effectively and raise the measurement accuracy to 10 ? 10/τ. The key technique of quantitative time-delay is the precision of delay unit as its resolution is determined by the time-delay stability of the delay unit. Passive wire delay, active delay device which can have a delayed effect to signal were studied and utilized as delay units. The contradiction in the frequency and time measurement based on the relationship of time-space is when the resolution is higher, the range is much narrow. This question limits the further improvement of the precision. Based on the principle of quantitative time-delay and the technique of delay chain, this paper presents a new frequency and time measurement method. The principle of quantitative phase-shift is as the same as time-delay. The delay frequencies that come from the reference frequency shifted at various delay chains are parallel counted on a same gate, which is equivalent to raise the clock frequency without improving reference frequency. This method can reduce the count error of±1. In theory, the precision can be improved as high as possible, as long as the delay unit fining enough. This system is designed on a single FPGA. Through the simulation of timing, the time-delay of the delay unit is 250ps. So the resolution of the system can reach 250ps.