A Super High Resolution Phase Difference Measurement Method

Phase difference measurement techniques can be used widely in positioning and length measurement, and high resolution is necessary especially for some science research purposes. In this situation the request to the measuring device is different from that to the frequency standard comparison. It is difficult to improve the resolution of conventional counting measurement method with some high-resolution approaches and the phase noise and frequency instability of frequency sources will influence the measurement precision obviously. In this paper we present a super high-resolution phase difference measurement method that can show near 0.1ps resolution. With a high-linearity phase difference to voltage conversion approach and high-resolution voltage meter, it is possible to get very high phase measurement resolution, and the phase noise of frequency source used in the measurement can be filtered partly. When this method is used to measure the frequency stability of frequency standard, the integration time of voltmeter should be very short. However, when the measurement purpose is for length the integration time of volt measurement can be longer and it is favorable for high resolution. The method is suitable for a certain range distance measurement in a certain period.