Study And Development Of Twoport Intelligent Measurement Adapter

The third generation of electronic measurement technology that takes virtual measurement technology as major method depends on its own various advantages and has widely attracted attention of the measurement field. The design takes virtual measurement goal as design thought to study and develop a kind of generalized test adapter in the front of two-port device with multiple parameters and meet the requirements of component measurement for low cost, high precision and multi parameters.It conducts analysis and research on measurement methods of various existing two-port component electrical parameters and combines with strengths and weaknesses of different methods, upon which the two-port component measurement method based on high-speed AD sampling technology is proposed and generalized measurement model for adapter is designed according to measuring principle.According to measurement model, hardware and software designed to adapter are respectively discussed in detail. Modularization idea is applied in hardware design part and Quartus II is utilized to design and verify main function modules on FPGA, including signal source module and AD control module. Principle for implementation of signal source module is DDS and mainly two signal sources are involved that the one is excitation source for producing drive signal with different types and frequencies according to different measurement objects. The other is sampling clock source for producing synchronous sampling clock signals with frequency similar to signal to be tested. In AD control module, according to the demand for principle of measurement, data collection method with controllable sampling clock frequency is proposed and AD control module that can produce programmable control sampling clock is designed to ensure the full-period sampling of signal. After hardware description, SOPC Builder is finally used to wrap these two modules to Nios II system custom component and add into adapter SOPC. In addition, SOPC Builder is used to add Nios II processer and general Nios II system peripheral module provided by Altera Company to establish SOPC for adapter. In order to meet the working requirement of various modules in the adapter, system peripheral circuit is designed, mainly including low-pass flittering circuit of drive signal, optoelectronic isolation circuit of sampling signal and conditioning circuit of sampling clock signal. In the software design part, C language is applied in Nios II IDE to design and develop system application software and solve critical problems like measuring system instruction of adapter, reception of measured parameter and measurement data transmission.Through verification, the adapter can produce stable excitation source with different high precisions according to different measurement objects and conduct full-period sampling for signal to be measured to ensure the feasibility of measurement. It is a beneficial exploration on software system of virtual measuring instrument and the third generation of component detection method which is of certain use value and promotional significance.