Design And Implementation Of The Automatic Oscilloscope Test System Based On LabVIEW

Digital oscilloscope integrated signal conditioning,high-speed acquisition,signal analysis and display,which can complete signal acquisition and measurement of main parameters.However,most digital oscilloscopes have a limited storage depth so that couldn't complete a long-time record.In addition,digital oscilloscope can not automatically set test parameters according to preset test sequences,so as to realize automatic measurement of different test items.Also,it can not automatically adjust the measurement parameters according to the amplitude and frequency of signals,so as to ensure the accuracy of measurement.Digital oscilloscope does not have self adaptability.Based on the engineering background of automated testing,a set of automatic testing software is designed under the LabVIEW platform which directs digital oscilloscope to accomplish automatic testing of preset sequences,adaptive measurement of unknown signals,and deep storage of data,etc.The main work of this thesis is as follows:First,by analyzing the advantages and disadvantages of the digital oscilloscope,the functional requirements of the oscilloscope automatic test system are put forward.According to functional requirements,the overall framework of the system is designed,which mainly consists of six modules,such as data acquisition,data storage,automatic test of presupposed sequence and self-adaptive measurement,etc.Second,automatic setting of the oscilloscope test parameters,automatic acquisition of signals and measurement of signal parameters are realized through data communication module and data acquisition module.A series of program is designed to save the real time data on PC side in the data storage module,which fully used the deep storage of PC hard disk and effectively solved the problem of insufficient storage depth of digital oscilloscope.The automatic measurement of complex sequences and the screening of signals are realized through the preset sequence automatic test module.And test efficiency is improved.Based on the data playback platform,the analysis of signal in time domain and frequency domain is realized through reconstructing the signal waveform and FFT of signal.Third,the method of signal adaptive measurement is studied in depth.By analyzing the control parameters of signal adaptive measurement,a method of signal adaptive measurement based on fuzzy control theory is designed.A Fuzzy controller which could adjust to the best measurement gear according to the signal amplitude or its frequency is designed under the LabVIEW platform.Through the method,measurement accuracy is improved and adaptive measurement of signal within the range is accomplished.A method of signal adaptive measurement based on binary chop combined with step control is designed to realize the adaptive measurement of over range signals.Fourth,experiments are designed to verify automatic test function,adaptive measurement of signal,depth of storage,speed of storage and other performance indicators.Besides,25Hz phase sensitive track circuit test site environment is set up.Automatic oscilloscope test system is used to record the test data of the choke transformer under different conditions to verify practicability of the system.