| CRT oscilloscope is the use of electronic properties of the human eye can not directly observe the alternating electrical signal converted into images displayed on the screen in order to measure the electronic measuring instruments. It is to observe the phenomenon of the digital circuit experiment, experiment, problem analysis, measurement results indispensable instrument.But the high price of traditional oscilloscopes limits its popularity, especially in individuals such as developers in the electronic design as well as the popularity of the students. Therefore, how to design a low cost oscilloscope will be useful to explore the contents of this article.For designing this Virtual Digital Oscilloscope a complete plan was put forward in this paper,and this plan was finished at last,making a Engineering prototype.With 1MHz bandwidth this Virtual Digital Oscilloscope can measure voltage from OV to 20Vpp,also it has 8_bit precision and its highest sample speed can reach 20Msa/s.Voltage scales are shifted by host computer programmed automatically without human interference. Signal sampling and restorage circuit which is made of MSP430F247,EMP240(CPLD),TLC5510,IS61LV256 etc can capture trigger level,save samples values in high speed,stop sampling under the control of FIFO logic circuit voluntarily. Under the control of MSP430F247,TI`s mixed signal processor,datas are read, pretreatmented and sent to PC.At the same time the shifting of voltage scale,the start and stop of sampling,the speed of sampling are all controled by main controler MSP430F247.This system has three sample styles and can capture glitch.Test proof that this Virtual Digital Oscilloscope can meet general measurment applications.
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