| PDC material sensor,also known as polymer-derived ceramic sensor,is a wireless passive temperature sensor.It is characterized by high temperature resistance and corrosion resistance.It is mainly used in high temperature measurement under harsh conditions.There is a resonant cavity inside this sensor.When its temperature changes,the resonant frequency of its internal resonant cavity will also change accordingly,and this change is inversely related to the temperature change.Based on this characteristic of the sensor,it can send a constant amplitude sweep signal with a fixed frequency band,and at the same time collect and analyze the echo signal reflected by the sensor,so as to obtain its resonance frequency and find the corresponding temperature value.The purpose of this paper is to make a complete system logic control for this new type of PDC material wireless passive temperature sensor.The main research contents are as follows:Firstly,research the working principle of the PDC material wireless passive temperature sensor by looking up relevant information,understand the characteristics of its resonant frequency change,and design a corresponding measurement scheme according to the working principle and characteristics of the sensor.Secondly,according to the designed measurement plan to write supporting system control logic,the system logic control is mainly composed of LMX2592 signal source control module,data singularity algorithm module,IIR filter module,AD data acquisition module,serial communication module and so on.The work flow is to control the LMX2592 RF signal synthesizer through FPGA to send a sweep signal with a constant amplitude according to the sweep algorithm written in the program.The frequency range is 6.30 ~ 6.50 GHz.The frequency reaches 12.6 ~ 13.0GHz after the power amplifier and frequency doubler,Then transmitted to the sensor through the circulator 1 port,and the echo signal is reflected from the circulator 3 port,and at the same time,the FPGA is used to control the AD9226 digital-to-analog converter to collect the echo signal converted by the detector into an electrical signal,and then the return The data is processed through the data singular point algorithm module and the IIR filter module,and then the processed data is sent to the host computer and the touch screen for data analysis and display through the serial port communication module through serial port transmission.The system code is mainly written in Verilog language and the various modules are simulated and debugged by Model Sim simulation software and Signal Tap II logic analyzer.Finally,combined with the system hardware,the whole set of RF temperature measurement system is actually tested.The main test methods are constant temperature and heating test.According to the actual measurement,the time period for measuring the temperature of the system is 0.55 s.At a constant temperature,the resonance frequency of the sensor will fluctuate about 800 k Hz.Under heating conditions,it is different between 25 ?-180 ? and 180 ?-350 ?.The temperature range was tested in sections,and it was found that in the interval of 25 ?-180 ?,the resonance frequency decreased by 291 k Hz for every 1 ? increase in temperature,the resolution was 0.00344 ? / k Hz;in the interval of 180 ?-350 ?,the temperature was The resonance frequency decreases by 324 k Hz when it rises by 1 ?,and its resolution is 0.00309 ? / k Hz.From the fluctuation of the resonance frequency at its constant temperature,the measurement accuracy is ± 1.3 ?,which meets the design requirements. |
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