| With the development of large scale programable technology , traditional instrument which has big cubage now can be taken place by portable instrument. Owe to the popularization of USB, the threshold of utilization has reduced greatly, so the periods of exploiture and the cost of exploiture can be accepted by most of development personnel, if combining the USB with large scale programable technology to rebuild traditional visualizer, the cubage of the traditional instrument can be reduced greatly, and a new attribute is obtained, it is Virtual Instrument.The dissertation's background is the task of high frequency digital undee visualizer based on USB in which the author participated. In this task, the author investigated that how the CPLD devices act as high speed data collecting card's manipulative logic core, how the USB transmission act as corresponding interface between collection card and PC, and A/D conversion, transmission and analysis has been implemented in this design. In this dissertation, the development of Virtual Instrument and the compare with traditional instrument is discussed, then the data collection card's function of each module and how to realize is introduced detailedly, furthermore, CPLD device's character, exploiture tool, and exploiture language is discussed, and how to implement each moudle's logic function is discussed either. After this, the USB protocol and the characteristic of USB device is introduced laconically, then the USB interface project scheme is given, the implementing process, principium of the USB drive and firmware program is introduced latish. Based on the analysis of high speed data collecting card's noise resource, the anti-disturbance design which has been adopted is pointed out in the dissertation. At the last of the dissertation, the strongpoint and disadvantage of the system and advice about how to improve it in the future are given.Under the background of future hi-tech local war, the information warfare...
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