Realization Of High Precision Frequency Stability Measurement System

As the frequency accuracy and frequency stability of crystal oscillator and atomic frequency standard continue to improve, better measuring equipment of these frequency sources are needed. Without means of measurement, we can’t properly assess the performance of frequency sources. Frequency measurements can be used not only to assess the quality of frequency source, but also helpful in improving the quality of frequency sources.This thesis describes the research status of frequency measuring instruments and frequency processing software at home and abroad, which highlights some representative frequency measuring instruments and frequency stability analysis software. The main indicators and characterization methods of frequency sources are introduced, including frequency stability characterization methods in the time domain and frequency domain, and the conversion method between them. Power law noise model was summed up to describe the various mechanisms which affect the frequency stability of frequency sources. We can determine the major noise types of frequency stability from the relationship between the sampling time and the time domain stability, or the relationship between frequency domain stability and the Fourier frequency. Commonly used methods in high-precision frequency measurement are frequency difference multiplication method, beat method, phase comparison method and dual mixer time difference method. Principles of these high-precision frequency measurement methods and the corresponding frequency measurement instruments are described, highlighting the advantages and disadvantages of the various methods of measuring frequency.Through the analysis of deficiencies of the prior frequency measurement instruments and measurement methods, we summarized their advantages and disadvantages, then proposed the development of frequency stability measurement system, including a high-precision frequency stability measurement instrument with wide frequency measurement range and a related frequency processing software. According to the different functions, the frequency measurement instrument can be divided into four main modules, including frequency offset source, mixing module, signal conditioning module and FPGA. Among them, the design of frequency offset source is the most important. Since the success in the design of frequency offset source, we make the realization of a high-precision frequency measurement instrument with wide frequency measurement range possible. By making a series of experiments in order to test the performance of this frequency measurement instrument, we find the measurement uncertainty of this frequency measurement instrument is 3.7E-13/ls when the frequency of the signal source under test is 10MHz.We are able to measure the frequency stability, the frequency accuracy and drift of any frequency between 1MHz to 30MHz, the average time from 100ms to 100000s. Experiments show that in the temperature range of 0～50℃, the frequency measuring instrument can maintain high measurement precision. When we compare this frequency measurement instrument with other frequency measurement instruments at home and abroad, we will find it very competitive in precision, frequency range and coverage in sampling time. The measurement result is real-time displayed by the graphical interface of frequency measurement software. Simultaneously, all measurement data will be stored for further processing.