VXI Oscilloscope Data Processing Software Implementation

Virtual instrument is a new instrument mode,which is an important development direction in the field of instruments.As an important part of virtual instrument technology,VXI bus test platform has been widely used in many test fields.The VXI bus oscilloscope module is designed to realize the basic functions of a general-purpose oscilloscope.It is suitable for general design and fault detection,and has good versatility.The VXI oscilloscope integrates computer hardware resources and instrument hardware through software,which combines the powerful computing processing power of the computer with the measurement and control capabilities of the instrument hardware.The development environment of the dissertation software is VC++6.0,and the programming language is C language.Based on the VXI oscilloscope project,focusing on the development of oscilloscope data processing software,the software design of waveform measurement and calculation module,random equivalent sampling module and automatic calibration module is realized.The main contents are as follows:1.Waveform measurement and calculation module: According to the IVI specification,the software adopts a bottom-up design mode.The waveform calculation is directly implemented in the application layer.The parameter measurement function is implemented in the oscilloscope-specific driver,and the calculated parameters are transmitted to the application layer through the class driver,thereby realizing the functions of measurement and calculation.2.The oscilloscope parameter measurement function is implemented in an oscilloscope-dedicated driver,and the calculated parameters are transmitted to the application layer through the class driver.Waveform operations are implemented directly at the application layer.3.Random equivalent sampling module: For the deficiency of traditional random equivalent sampling,a signal reconstruction method based on Shannon interpolation is cited.This dissertation analyzes the quantization error problem of sampling relative time in traditional equivalent sampling.According to the relative time of sampling before quantization,the Shannon interpolation theorem is used to derive the data of all integer positions after quantization,which improves the accuracy of waveform reconstruction.4.Automatic calibration module: Analyze the correlation between the hardware structure of the oscilloscope signal conditioning channel and the calibration parameters,and improve the calibration method of the oscilloscope.When the trigger level is calibrated,both the positive and negative offsets of the trigger level are calibrated,which improves the accuracy of the trigger level.In DC gain calibration,the programmable attenuator coarse adjustment and the ADC gain fine adjustment,combined with calibration,improve the DC gain calibration accuracy.In the trigger level and channel offset calibration,calibration of all amplitudes of the channel is done by calibrating only one amplitude range.Under certain calibration accuracy,the time of automatic calibration is greatly shortened,and the efficiency of automatic calibration is improved.Through the research of each module mentioned above,the VXI oscilloscope data processing software implementation is completed.Among them,the modular programming method used in this dissertation makes the software structure clear and convenient for system debugging.