Research On Passive Wireless Temperature Sensor Based On Transistor

As an important sensor with strong practicability and wide popularity,temperature sensor are widely used in important fields such as industry,manufacturing,construction,pharmaceuticals and aerospace.How to perform temperature detection stably,accurately,and conveniently is currently a major problem faced by temperature sensor designers.Under harsh conditions such as high temperature,high pressure,high voltage,strong current,strong corrosiveness,or small space,many traditional temperature sensors can no longer meet the current needs or even fail.At the same time,traditional active wired temperature sensors also have disadvantages such as bulkiness,high maintenance costs,and the need to replace batteries,power supplies,and wires on a regular basis.Therefore,it is extremely valuable to study and design a passive wireless temperature sensor that can be used in harsh conditions.Based on normal temperature semiconductor maser theory,this paper designs and fabricates a passive wireless temperature sensor system based on transistors.The probe is characterized by small size,easy integration,and no DC power supply.At the same time,the system designed and produced a high-performance reader and a low-cost reader based on the characteristics of the probe.Finally,the system can achieve high-precision temperature measurement tasks under severe conditions such as strong electromagnetic fields,strong voltages,and high temperatures.The main work and results of the thesis are as follows:1.Analyze the common types of temperature sensors on the market at present,sort out the development history of temperature sensors,briefly describe the domestic and foreign research trends of passive wireless temperature sensors,and finally point out the development trend of temperature sensors.2.The normal temperature semiconductor maser technology is described,and passive wireless temperature sensing probes are made based on this technology.Finally,the probes are rested with signal source,vector network analyzer and other equipment.The probe input frequency is about 800 MHz,the sensitivity is-15 dBm,and the output center frequency is variable according to the design requirements.The currently completed probe output center frequencies are 773 MHz,770MHz and 768 MHz,the output power is about-38 dBm.3.A high-performance reader and a low-cost reader are made for the passive wireless temperature sensor.First,the common structure of the transceiver is briefly described and the key indicators of the transceiver are analyzed.Then the chip selection and architecture planning of the transceiver are carried out.Finally,the transceiver system is simulated with the aid of ADS software,and the system transmission power is5W(37dBm),the receiving sensitivity is about-70 dBm.4.Designed and manufactured the system control and digital signal processing links.The system signal source driver program is written,and the system transmission frequency and power are changed through program.The STM32F429-based frequency counting function in the low-cost superheterodyne receiver was made using the KEIL IDE environment,which can directly extract the frequency of the input signal.Using VIVADO,a digital down-conversion system in a high-performance digital intermediate frequency receiver is made.5.The overall test experiment of the system is carried out,and it is obtained that the system can complete the temperature measurement task between 20℃ and 110℃.Finally,the system designed in this paper is summarized and prospected.