Hardware Design of RF Temperature Measurement Transceiver System Based on Delayed Linear SAW Temperature Sensor

This article first studies the working principle of a wireless passive SAW (Surface Acoustic Wave) temperature sensor. The pulse query signal is used to excite the sensor. After the sensor is excited, it returns the pulse signal reflected by each reflector. By measuring the phase difference of the pulse signals returned by the reflectors inside the sensor, the temperature of the sensor is estimated by the phase difference. The measurement scheme is given according to the principle of the sensor, and a matching RF temperature measurement system is designed based on the FPGA as the main control chip. The test results show that the temperature measurement system designed in this paper has a temperature measurement range of $25^{\circ}\mathrm{C}-130^{\circ}\mathrm{C}$, a measurement error of $0.6^{\circ}\mathrm{C}$, and a wireless signal transmission distance between the measurement system and the SAW temperature sensor is 100mm.

I. Introduction

In modern society, sensors have long penetrated into many areas of human production and life, and they are widely used in many fields such as industrial automation, aerospace, transportation, medical health, and smart home [1]. Temperature information is a vital parameter to be tested in production and life. However, in some special applications such as vehicle tire pressure and temperature measurement, the measured target is often unable to be directly connected to the sensor, or it may cause mechanical and electrical problems and safety hazards [2], which requires wireless. A temperature sensor system that transmits temperature information in the case. The delay line type SAW temperature sensor is a wireless passive temperature sensor. Designing a temperature measurement system based on this sensor can overcome many of the shortcomings of traditional temperature measurement methods and can be widely used in high-speed rotating objects and in closed non-contact working environments [3].