Research On Signal Acquisition In Digital Electronic Experiment Teaching Instrument

In traditional physics and electronics experiments,DC power supply,signal generator,voltage and current meter and oscilloscope are the basic instrument configurations.However,a large number of instruments and equipment often occupy a large area of the experimental table.As the result,not only the operation is inconvenient,but also the experimental cost is higher.Therefore,the integrated multi-function and digital portable electronic experimental teaching instrument is the developinf direction of experimental teaching instruments in the future.In this paper,two key technologies of digital electronic experimental instrument,high-speed data acquisition and medium and low speed data acquisition,are designed and studied.The main content of this paper is to design the software and hardware of the high speed data acquisition circuit and the medium and low speed data acquisition circuit for the application of the digital electronic experiment teaching instrument.In the high-speed data acquisition part,a design scheme of data acquisition and storage based on FPGA is proposed,including the design of FPGA control module,A/D analog digital conversion circuit module and dual FIFO memory module,and SDRAM large capacity dynamic storage module.In the middle and low speed data acquisition part,the signal preprocessing circuit and A/D analog digital conversion circuit,ARM control circuit and corresponding software are designed.In addition,the paper also analyzes the noise interference often encountered in the middle and low speed data acquisition process,establishes the noise model,and designs the digital filter to eliminate the noise.The main work and innovation of this paper are as follows:(1)To solve the problem that traditional "MCU controlled analog to digital converter" data acquisition mode cannot exceed data sampling rate over 1MHz,a solution of the FPGA controlling time sequence signal which required to produce high speed AD is designed,and the high speed data acquisition function of the 100MHz sampling rate is realized.(2)A dual FIFO caching scheme is designed in FPGA,which solves the difficult problem of data loss when high speed data acquisition encounters in high speed and large amount data transfer to SDRAM.(3)In the medium and low speed data acquisition circuit,the relay switching control circuit is designed,and the adaptive automatic range transfer function of the wide voltage input is realized.(4)The source of noise in the middle and low speed data acquisition circuit is analyzed and studied.The noise model is established and the height of the noise is estimated quantitatively,and the digital filtering method for removing noise is designed.(5)Ping pong caching method is used to solve the problem of data storage,digital filtering and data uploading parallel processing taking place in mid low speed data acquisition.The high speed data and medium and low speed data acquisition schemes designed in this paper proved to be correct and reliable through real experiments.It has reached the requirements of data acquisition for various speed of digital electronic experiment teaching instruments in general university physics experiment and electrical and electronic experiment.At the same time,the whole design has the characteristics of low cost,small volume and so on,and has wide application value.