Research And Design Of Handheld High Precision Frequency Counter

Electronic measurement is the basis of the electronics industry,but also an indispensable important measurement means of general industry.Because electronic measurement technology has the advantages of wide measurement range,high precision,good repeatability,large dynamic range and strong integration,it is widely used in scientific research,experimental testing,industrial and agricultural production,communication,medical and military fields.Time and frequency measurements,as an important part of the field of electronic measurement,have been extensively studied.In physics experiments,many physical quantities are measured by converting into time and frequency quantities.Therefore,frequency measurement plays an important role in scientific experiments and engineering applications.In order to measure the frequency of the signal more accurately,it is necessary to require more accurate frequency measurement methods and more advanced frequency measurement instruments.The frequency counter which bases on traditional frequency measurement principle to achieve a simple application is more,but its measurement accuracy is low.It is simple to realize the frequency counter using the traditional frequency measurement principle,but its measurement accuracy is low.Although the universal frequency counter has high measuring precision and multi-function,but often the equipment is complex,the price is expensive,and the instrument volume makes use inconvenient.Therefore,according to the actual measurement needs,this paper designs a handheld high precision frequency counter,using equal precision frequency method as the measurement principle,and it can guarantee a constant measurement accuracy in a wide range of measurement.System adopts the scheme of the combination of FPGA and MCU in follow the principle of the instrument of economy as well as the ease of use and has reached the requirement of high accuracy of measurement.Contents in this paper can be summarized as follows:(1)The methods of frequency measurement and the status of frequency measurement instruments are summarized.The equal precision frequency measurement method is mature,high precision and easy to achieve.Although universal frequency counter has many measuring functions,but its equipment is more expensive and larger.Therefore,this paper proposes the design of a handheld high-precision frequency counter to improve the ease of use and portability of the instrument system.(2)According to the measurement requirements of the system,the error of the principle of equal precision frequency measurement is analyzed.The analysis shows that the precision measurement method can achieve the required measurement accuracy,and it is suitable as the measurement principle of this design.The realization scheme of the system is demonstrated,and the combination of MCU and FPGA is the overall structure of the system.(3)The hardware circuit of the frequency measurement system is designed,and the system printed circuit board of the 4-layer structure was designed.The FPGA module software is designed to realize the frequency measurement function,and the MCU module software is designed to realize the calculation and control function.Through the debugging and verification of the hardware and software of the system,it is proved that the system can realize the required function.(4)The influence of the reference signal frequency error and the counting error on the measurement error is analyzed.The measurement error of the system is obtained by the measurement experiment.The experimental results show that the actual measurement error range of the frequency counter is 0.46 ppm ~ 0.88 ppm,which achieves the design requirement of 1ppm.It is concluded that the measurement accuracy and measurement range of the system meet the design requirements.And it has good stability and operability.