| The emergence of virtual instrumentation based on general computer has changed the concepts, modes and structures of traditional electronic measuring instruments. Users can customize the functions and parameters of instrument that is "software is the instrument".The low-frequency virtual oscilloscope mainly includes three parts they are data acquisition systems, communications interface and an application program for virtual panel. The work principle of virtual digital-storage oscilloscope is like this:the analog signal through the data acquisition system for data acquisition; and then sampled data, which is uploaded to computer through the USB interface, is analyzed and processed by the virtual panel application according to the differ actual request of the user; finally, the results are displayed on the screen in different ways.According to the goal of design, firstly, the overall design of the system is given; then the design methods of hardware are described in detail; also the reliability and anti-interference technologies used in the hardware and software design are described. Secondly, the design methods of software system for the low-frequency virtual oscilloscope are described in detail. Last, a prototype is developed successfully. The process of the test is described in detail with some examples used to verify the system. Also, all works investigated are summarized, and the further research is indicated.This development way can form independent setup software package and run independently from the development environment, accordingly, its setup is easy and has a strong practicability. The parameters tocontrol 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 it can be widely used in teaching or experiment, but is not suitable in engineering for its low sampling rate and precision. |
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