Design And Study Of Wireless Passive Resonant Sensor Measurement System

With the advantages of small installation size,low production cost,high sensitivity,wireless transmission and no external power supply,wireless passive resonant sensors have been widely used in environmental monitoring,industrial control,medical health and other fields.Researchers have conducted research on the design of wireless passive resonant sensors for wireless reading units,but there are generally problems such as single test parameters and functions,high cost and complex structure.Therefore,it is of great value to design portable,low-cost,high-precision and functionally integrated wireless reading units.In this paper,by analyzing the basic transmission principle of wireless passive resonant sensor and its equivalent circuit,a complete wireless passive resonant sensor measurement system is designed,and the measurement system is tested and verified.The main research of this thesis includes the following aspects:1、Based on the principle of reflection coefficient measurement,this paper designs a measurement circuit for wireless passive resonant sensors,in which the sweep source module,low-pass filter group module,power amplifier module and signal separation module complete the excitation of the passive resonant sensors,and the amplitude phase detection module and analog-to-digital conversion module complete the calculation and conversion of the reflected signals.The FPGA chip is used to control the whole hardware circuit,and the portable and high-precision measurement of the wireless passive resonant sensor signal is successfully realized.2、A set of easy-to-operate and functionally integrated measurement system software is developed based on Lab VIEW virtual instrumentation technology.The software realizes the dynamic control of the measurement circuit and the real-time extraction and display of the resonant frequency of the sensor,and also supports the efficient database management function.The main design contents include real-time data acquisition and display,database interaction program,sensor calibration and decoupling program,and other auxiliary function programs.3、The performance of the temperature and pressure composite test platform was tested through static and dynamic test experiments and compared with the commercial network analyzer.Experimental results show that the maximum relative error of the measurement circuit is 0.96% in the temperature range of 25℃-550℃.For the interference problem between parameters,the corresponding decoupling algorithm is proposed,and the experimental results show that through the dynamic calibration and decoupling test of the sensor,the maximum error of the decoupling temperature value is 1.51% and the temperature range of 25℃-550℃ and the pressure range of 0 k Pa-100 k Pa.