Design Of A Micro-impedance Instrument

Virtual instrument for the advantages of its high performance, scalability, lessdevelopment time, seamless integration, etc, is drawing public attention and showsmore and more powerful in the testing field. The virtual instrument technology in thelaboratory experiments can reduce costs, improve the quality and efficiency ofteaching and research.Based on the virtual instrument technology, this article introduced a newimpedance meter based on free-axis method, achieving measurement of the measuredparameters. It introduced the experimental system from the aspects of virtualinstrument software platforms, hardware platforms and system integration in detail.The software which used LabVIEW as the programming tool was designed. Itachieved the transmission, analysis, processing of and display of data and the controlof the hardware modules through the upper software programming, fully reflecting itsflexibility. The software called the driver program of the module in the form ofdynamic link library, to program hardware and make the instrument reconfigurable.The tester which used FPGA as the basic hardware was designed. It specificallydescribed the design implementation for each module of the hardware circuit. Thehardware circuit fully played its low power consumption, large storage space, strongsequential logic functions and other characteristics. In addition, the sensitivity andaccuracy was improved by use of digital full-wave phase. The control-board usedUSB2.0to realize the PC communication. The module of USB communication iscompleted by89C52, the firmware adopts the method of front-and-back to enhancethe transplantation of software. The functional module with the3U sizes wasintegrated into the3U box through the standard bus. Therefore, the functionalreorganization of modular instruments can realize the different testing functions,which reflects the advantage of the virtual instrument technology.The system takes full advantage of the modern PC technology, realizing theadvantages of a micro-impedance instrument, such as no power, minitype, portability and automatic measure. The PCB layout was fully considered during the process ofcircuit design, which enhanced the anti-jamming of the system. It is a beneficialexploration of means and hardware system developed for a virtual mini-impedancetester, and it acquires good results. It’s validated by rigorous testing that the system ishigh accuracy, easy for operation, real-time and low power. Therefore, the system hassome values of use and promotion and can be widely utilized for laboratory ofcolleges and the other fields.