The Research On Virtual Oscilloscope And DDS Signal Generator

The virtual oscilloscope is a newly emerged intelligent instrument along with the development of computer technology and measurement techniques. In addition to all the common functions of a traditional oscilloscope, by making full use of computer's resources, it makes such functions as data storage and analyses possible, which were very difficult to realize on a traditional one. Therefore it is of much practical importance to carry out theoretical and experimental research on virtual oscilloscopes.The thesis developed a virtual oscilloscope in the configuration of PC-DAQ and utilizing Lab Windows/CVI software platform, which offered such advantages as low cost, function redefinition by the user, updating and expending by software, easy interface with PC, good reliability, transplantation and easy maintenance.In hardware design, analogy to digital converter TLC5510 from Texas Instruments Corporation and first-in-first-out memory CY7C425 from Cypress Semiconductor Corporation were used for ultra high speed data acquisition and buffering. Data transfer from data acquisition board to PC were realized with the aid of micro controller P89C61X2 and USB interface device PDIUSBD12 both from Philips Semiconductors Corporation. In addition a digital signal generator was incorporated via a DDS chip AD9850 from Analog Devices Inc, featuring accurate frequency preset, quick phase transformation and low phase noise. In software design, application program on PC was composed using VC++6.0 language and LabWindows/CVI environment, which display waveform directly on PC screen. Firmware and driver for USB device were also discussed in detail.