Virtual Frequency Characteristics Of The Research And Design Of The Tester

Virtual Instrument represents a fire-new concept of instrument. Because of combining with computer technology, Virtual Instrument can make use of the computing power and software of modem PC to realize some function that traditional instrument can't realize.This thesis put forward a scheme that make use of technology of VI to realize frequency characteristic test instrument, aim at the disadvantage of traditional frequency characteristic test instrument. The key technologies of Virtual frequency characteristic test instrument are mainly described in this thesis. Firstly, the circuit design of the instrument are described detailedly, including the circuit of serial communication interface, the circuit of sweep signal generator, the circuit of amplitude measurement, the circuit of phase measurement. Secondly, the algorithm of fitting transfer function is introduced. Finally, the software of the instrument is described.The frequency characteristic test instrument based on the technologies of VI can print the plots of frequency characteristic of the measurand, also can give the approximate transfer function of the measurand. But these functions are hard to be realized by traditional frequency characteristic test instrument.