The Design Of Digital Oscilloscope Based On The Technology Of Virtual Instrument

Testing instruments are the important tools in science research. Every instrument includes three function components. They are signal acquisition and control, signal analysis and processing, expression and output of results. The functions of traditional instruments are executed through hardware, which decides that the functions and structures of traditional instruments are only defined and manufactured by the instrument manufacturers. And the users cannot change the factions optionally. With the development of computer science technology the virtual instruments appear, which achieve the perfect combination of computer science technology and instrument technology. The three function components of instrument are executed through computer. So the functions of traditional instruments can be executed and enhanced through the computer science technology which develop rapidly. It initiate the new era that the instrument users can be the instrument designers. Virtual instruments delegate the direction of instruments.Conform the trend of instrument development, in this design the author adopts Lab Windows/CVI software development environment based on ANSI C library, using skillfully DLL technique, develops double-channels virtual oscilloscope. First, the system of data acquisition in this instrument is the data acquisition card designed based on USB2.0 bus technology, the maximum sample rate of which is 100MSPS. Second, the design of software part is based on LabWindows and VC++ this two different methods to finish the same function. At last, using the advantage of computer in the field of data processing, it made some analysis and calculation for waveform data. At the same time, it added the spectrum analysis as a extension of oscilloscope's functions. This dissertation introduced concretely the course of using the two different development tools to develop the application program. And it summed up the advantage and disadvantage of this two development tools, and made a comparison in technology.This two development ways can form independent setup software package and run absolutely deviating the development environment, accordingly, its setup is easy and has a strong practicability. The cantonment of parameters of the virtual instruments is all processed through the graphic interface in this thesis. The design of the interface is visual and easy to handle. And the users can change, improve and expand the functions of virtual instruments through corresponding programs. They can be widely used in engineering signal analysis, fault diagnosis and so on.