Research And Implementation Of Frequency Signal Digital Comparison Processing Technology

Frequency standard comparison technology,as the most commonly used method for processing frequency signals such as periodic signals,is widely used in GPS navigation,astronomical measurement,computer technology,electronic technology and other aspects.The phase comparison of two signals with large frequency differences usually requires normalization of the frequency,which makes the system complicated and is not conducive to the use of frequency standard comparison technology in a wide range of measurement fields.In this thesis,through the study of traditional phase comparison methods,the concept of generalized phase processing is introduced,and the phase comparison between frequency signals with different nominal values is extended into the phase group,and the different frequency signals are studied in the phase group.In a single period,the phase difference changes irregularly,but if the interval is the least common multiple of the two matched signals,it can be found that the phase difference changes are continuous between the groups,which is consistent with the periodic signals.Inherent laws.The introduction of the phase group makes direct phase comparison in a wide frequency range possible.On this basis,combined with the application of digital technology and cursor effects in digital measurement and phase-locked loop technology,the reference signal and the measured signal are sampled at the least common multiple period or an integer multiple of the interval,and the nominal frequency value can be obtained directly Information about the phase difference between any two signals and lock the frequency source.The LabVIEW monitoring software in the digital comparison system can store and process the sampled signal in real time,and display and measure the frequency and frequency stability of the measured signal in real time.The phase-locked loop part uses the voltage and output frequency of the voltage-controlled crystal oscillator(VCXO)and the relationship between the frequency difference and the phase difference.According to the phase difference information,the DAC output controls the voltage signal of the voltage-controlled crystal oscillator.And then it can lock the output frequency of the voltage-controlled crystal oscillator.The digital comparison system designed in this thesis directly transmits the quantized phase difference information acquired by the ADC to the host computer.The host computer monitors the system and can clearly see the change law of frequency stability;in one or more minimum The phase comparison in the common multiple period does not require frequency normalization processing for frequency signals with different nominal values,which simplifies the system.The digital comparison system can realize the measurement display and phase lock control of the frequency and frequency stability of various frequency signals,and the frequency stability measurement can reach the E-12 level,which is stable to the frequency of the frequency source.The degree also has an improving effect.The system is simple in structure and easy to operate,and has important significance in time and frequency measurement such as frequency and frequency stability.