Research And Design Of FMCW Radar Material Level Measurement System

Material level measurement is a measure of the amount of material stored in the container.It is an effective means to adjust the material balance and determine the output of the product.It is very important to measure the level in the process of automatic industrial production.With the continuous improvement of China's industrial development level,high precision and high reliability of the level measurement technology has been rapid development,FMCW radar with its simple structure,low transmit power,high accuracy and high anti-interference ability,is widely used in the field of level measurement.Therefore,it is of great significance and value to the research and design of FMCW radar level measurement system.Firstly,the principle of related technology of FMCW radar level measurement system is introduced.The principle of distance measurement of sawtooth wave FMCW radar and the communication technology based on HART protocol are described.On this basis,the overall framework of level measurement system is put forward.Level measurement system consists of five parts:signal processing and control module,HART communication module,power supply module,infrared input and LCD display module and radar transceiver module.The signal processing and control module selects the STM32F407 processor based on ARM Cortex-M4 kernel as the core of signal processing and peripheral control,and designs the control interface of radar transceiver module,HART communication module,infrared input and LCD display module.The HART communication module is built with AD5421 and AD5700-1 chip to realize the hardware design of the module.The power supply module supplies power to each module of the system.Due to the high demand of AD sampling circuit and microwave circuit of radar transceiver module,the output voltage of power supply module must be stable and low noise.The infrared input and LCD display module realizes the man-machine interactive function of the system,which is convenient for the reading of the measured data and the setting of the debugging parameters.Secondly,the difference frequency signal processing algorithm of FMCW radar is studied.When using radar for level measurement,the echo signal is often mixed with a large number of clutter and noise interference,in order to identify the target echo from these interfering signals and determine the exact distance of the target,this paper chooses the signal processing algorithm based on FFT + Chirp-Z and OS-CFAR,it is proved that the algorithm can well detect the target from the spectrum of the difference frequency signal and realize the estimation of the target frequency.Then the software of the level measurement system is designed.Through the analysis of software requirements,the software design is divided into two parts.Signal processing and control software is mainly responsible for the realization of signal processing algorithms and related peripheral control,HART host computer software is achieved HART communication with the level measurement system.Finally,this paper tests the function of each module of the system.The test results show that.the FMCW radar level measurement system can work normally,ranging accuracy is ± 15mm,and it is suitable for industrial site measurement.