Usb-based Virtual Digital Storage Oscilloscope

With the modern checking and surveying technique developing to be intellectualized, networked, integrated and digital, computer that has high efficiency and fast data processing capacity becomes to play a more and more important part now. Virtual oscilloscope, a late-model high-tech product, taking full advantage of existing computer resource, substitutes some hardware of traditional instrument with computer software, thus it has many powerful functions such as data acquisition, analyzing, disposing, displaying, memorizing and network releasing and so on. Furthermore, virtual digital storage oscilloscope based on USB interface, with more advantage of plug and play, dispensing with exterior power supply and convenient use etc., has displayed driving vitality, represents the developmental direction of testing and surveying instrument, and will consequentially gain a broad application in testing field.This paper proposes a design of virtual digital storage oscilloscope based on USB interface. The data acquisition system of oscilloscope adopts two sampling methods, that is real-time sampling and equivalent-time sampling. The transmission of sampling data, from A/D converter calibration to memory to the outer CMOS chip of USB, implements DMA transmission mode under the control of high speed programmable logic device. The panel of virtual oscilloscope introduces Lab VIEW graphic programming language to program.This paper, first of all, refers to the attributes and merits of virtual instrument, digital storage oscilloscope and USB interface. Then, from two aspects of hardware and software system, it gives detailed designing demonstration of virtual digital storage oscilloscope based on USB interface. In addition, it puts forward the matters that must be paid attention to anti-jamming measures etc. in circuit design. Finally, by testing the performances of the system with an oscilloscope adjustment and comparing the results with that of digital storage oscilloscope HP54601B produced by HP company, it analyzes the performances of the system and signal wave. By testing, the system has reached the indexes requirement of ordinary oscilloscope, vertical deflection system precision is less than ±3%, the accuracy of horizontal scan time coefficient is less than ±3%, rise time is less than 15nS,and for stochastic signal that under lM,it shows better capacity of wave-appearing again and higher precision.