Direct digitalized phase comparison between signals with different nominal frequencies

Zhiqi Li,Wei Zhou,Xiaolong Chen,Chenyuan Xue,Ning Yang

doi:10.1063/1.5105382

Abstract

In this paper, the direct digitalized phase comparison which has phase continuous and high resolution is proposed to measure the phase variation of the high-precision frequency standard with different nominal frequencies. During the least common multiple period, the phase difference between the two comparison signals is regular, therefore the phase comparison between arbitrary frequency signals is achieved directly through using a high-speed analog-to-digital converter as the counter and the equivalent phase-detecter. By experiments and analysis, it was shown that no-interval frequency measurement can be converted into the phase difference measurement and the frequency stability evaluated as the Allan deviation accords with the change law of 1/τ.

Highlights

Phase difference between two periodic signals with different nominal frequencies is shown in the Fig. 1
Phase comparison can be achieved by no-interval frequency measurement because of the regularity of phase difference groups
Phase comparison between the reference signal and the measured signal of different nominal frequencies can be directly realized when the interval of comparison is expanded to the least common multiple period (LCMP)

Summary

INTRODUCTION

Phase difference between two periodic signals with different nominal frequencies is shown in the Fig. 1. High resolution frequency measurement and wide range phase comparison can be realized by combining the two technologies. Phase comparison between the reference signal and the measured signal of different nominal frequencies can be directly realized when the interval of comparison is expanded to the least common multiple period (LCMP).. The variation of frequency stability with the sampling time is 1/τ This method is more suitable for long-term signals comparison and is an effective method for the development of future frequency standard and phase processing between signals with different nominal frequencies. It can build a phase detector for laser interferometers

MEASUREMENT THEORY

EXPERIMENT AND VERIFICATION

CONCLUSION