Wireless Passive Surface Acoustic Wave Temperature Sensor Reader System Design

As the key technology of industrial intelligence,sensor technology plays an important role in industrial production.SAW sensors have the characteristics of high sensitivity,light weight,multi-parameter sensing,etc.,so they are widely used in the sensing of physical quantities such as temperature,pressure,humidity,etc.It plays an irreplaceable role in harsh environments such as high pressure,confined space,and high-speed rotation.The wireless passive reader system is the key for the SAW sensor to work normally in the above-mentioned harsh environment.Therefore,the study of the corresponding reader system has important practical value.This paper mainly conducts theoretical analysis,program formulation,sample production and related tests on the surface acoustic wave temperature sensor and wireless passive reader.The specific contents are as follows:Firstly,starting from the single-port SAW resonator,the temperature measurement principle,equivalent circuit model and signal characteristics of the SAW sensor are analyzed.According to the signal characteristics of the sensor,the working principle and system architecture of the reader are analyzed.Secondly,the overall scheme of SAW temperature sensor wireless passive reader system is designed,and the hardware circuit and software design of the reader are analyzed and designed in detail.The reader system mainly includes a transmitting link,a receiving link,a data processing and control unit,a host computer and an antenna.Through the control of the direct digital synthesizer and the phase-locked loop,the transmission chain generates an electromagnetic wave excitation signal with high frequency resolution,and the power amplifier is used to amplify the excitation signal,which accurately excites the SAW temperature sensor;the reception chain The data processing and control unit uses DSP technology to efficiently and quickly analyze the echo signal in the frequency domain and realize The communication with the host computer is realized;the host computer receives and saves the temperature data from the DSP,and displays the temperature waveform in real time to achieve the purpose of monitoring the temperature in real time.Finally,a wireless passive temperature and distance sensing test platform is built,and the reader system is tested.The test results show that the system can generate a continuous frequency step wave of about 433 MHz with a power of 22 d Bm,and can achieve a wireless test distance of 180 cm,and the temperature sensing error is ±0.1℃,and it can achieve better temperature measurement accuracy and stability,indicating that the reader system is feasible.