The Realization Of The New High-precision Frequency-measuring Instrument

This paper discusses a high-precision frequency measurement method based on phase coincidence detection technology .This frequency measuring instrument synchronizes measuring gates, test signals and standard frequency signals by using essential regulations of phase difference relationship between periodic signals. So the instrument can avoid the counting error of plus or minus 1 word in theory when counting the pluses during gate signal. The error precision is greatly enhanced when compared with the traditional methods. The paper analyzes the mutual phase relationship between periodic signals, and several special concepts which are used to describe the characteristics of periodic signals are given in the paper. We also analyze the frequency measurement methods based on the theory of phase coincidental detection and its error. The paper presents the overall design of hardware structure, the key circuits design and emphatically introduces a circuit for signal disposal and circuits design methods about phase coincidental detection. The error analysis model is finally given in practical circuit design. Actual test shows that the frequency measurement precision of the proposed method can reach to magnitude and far beyond the measurement accuracy of traditional methods.The second task of this paper is to research the expanded use of the principle ,and gives a frequency standards comparison system combined by phase coincidence detection technology and magnifying the frequency difference method. Theory shows that this method can get much higher accuracy. The paper also represents the application of phase coincidence detection technology in phase difference measurement between periodical signals with whole solution and calculating formula for the design. With the further study, this technique will develop into the most advanced technology in the field of measurement.