Research On Virtual Oscillograph Based On USB

The virtual instrument takes full advantage of the software and hardware resource of the computer, and combines the computer technology and the measurement technology tightly. With the combination of the computer and the measurement device, the virtual instrument not only has the functions of the traditional instrument, but also has many extra functions by using the computer software program; what's more, it can reduce the cost of the whole equipment. Virtual instruments that based on the Universal Serial Bus interface effectively solved the problems with the traditional bus such as low speed, hard to install, easily be interfered, be limited by the resource of the computer, and they have large practicability and value to research because of their low cost, high speed, plug and play, easy to use and take cake. The virtual instrument that based on the USB interface is going to be the trend of development in the measurement area and has expansive improveing prospect.A virtual oscillograph which is based on the USB bus is designed and developed in this thesis. The principal content of this thesis includes the design of the hardwire connection and software programming. The signal conditioning circuitry, the analog-to-digital conversion circuitry, the data buffer circuitry and the USB interface circuitry are designed in the design of the hardwire connection. The signal conditioning circuitry adjusts the signal to the best differentiate range of the analog-to-digital converter, the analog-to-digital conversion circuitry converts analog signals to digital signals and the USB interface circuitry transmits the result of the analog-to-digital conversion to the PC. The application program that is programmed with the LabVIEW software has actualized the function of digital signal processing and the human-computer interaction, and the human-computer interaction can display the result of measurement and incept commands. In the end of the thesis, a study of the problem of antiinterference is made.The practical application indicates that this virtual oscillograph based on the USB has many merits such as facility, easy to use, agileness; in addition, it is low cost, powerfull and has high precision and stability. A great variety of automatic test systems will be constructed and the hardware and software resources can be shared. Signal sampling, digital filtering, spectral analysis and waveform display can be done by using the powerful function of the computer, and the data that has been acquired also can be stored, playback and partaken of.