Research On Precision Measurement Of Phase Difference

It is used widely in automation and communication domain.The common way of measurement is change the input signal into rectangle waveform after modulation and pass-zero detection. The "and" operation of two input rectangle waveform will bring the phase difference pulse. We use this pulse as the control of counter. It means we take count of clock pulse during the phase difference pulse and get the phase difference later. But errors lies in the way of counter lead the bad measurement, especially when it needs high precision or the clock pulse is wider than the difference.After sample analyzing several common measure ways, it brings up counting repeatedly during multiple signal periods including the time delay of two signals and not in different circuit at the same time. The difference of two counters is the number of clock pulse in time delay. And the ratio of the number of clock pulse in delay time and the number in signal period is the ratio of delay time and the signal period. It can get the phase difference from the ratio.We choose the CPLD as the processor in counting system. And it makes the capability of system is much higher than singlechip system. It meets the need of our measure system. It is validated in our lab test that it is a very efficient and simple project of exact phase difference measurement.