| Accurate measurement of target distance is of great significance in practical life and industrial production,such as petroleum,chemical industry,construction,mining and other object level and liquid level measurement,there is a great demand for accurate measurement of target distance.Especially in the scene which is not easy to measure directly,non-contact measurement is required,and radar,as a non-contact sensor,can meet most of the range measurement application scenarios.Millimeter-wave radar has the advantages of all-weather,large bandwidth,strong anti-interference ability,and the current millimeter-wave radar sensor integration is very high,the application of millimeter-wave radar sensor system development is more convenient,this academic dissertation on high precision ranging millimeter-wave radar system to do the main research.Firstly,this academic dissertation analyzes the research status of millimeter wave radar chip and millimeter wave radar system at home and abroad,and introduces the composition,ranging and target detection principle of frequency modulated continuous wave radar system.Then,based on millimeter wave radar chip,a high-precision ranging system is designed for object position and liquid level measurement.The ranging system is divided into three parts:the feed structure of the system antenna and the dielectric lens horn antenna,the low power supply and the radar rf board,and the realization of the system software program.(1)The feed structure of the system antenna and the dielectric lens horn antenna are designed,and the antenna index is proposed by deducing the formula of the radar equation,as well as the requirement of the maximum range and radar Angle of view.In the design of the microstrip rotating waveguide structure fed by the antenna,including the simulation of microstrip patch unit,circular waveguide and loading anti-static structure,the simulation results show that in the working band of 77～81GHz,the return loss is basically less than10 d B,and the insertion loss is about 4.4d B.Due to the influence of the anti-static structure,the insertion loss is slightly larger.In the design of dielectric lens horn antenna,the aperture diameter is 73.1mm and 93 mm.Compared with the lens antenna with the aperture diameter of 73.1mm,the simulation results show that in the frequency band of 77～81GHz,the gain is greater than 29.2d B and the beam Angle is less than 4°,which meets the basic requirements of antenna for ranging system.(2)The low power supply and radar RF board are designed.Firstly,the solutions of radar chip manufacturers are compared,IWR1843 radar chip of TI is selected,and the system hardware design block diagram is given.Low power supply design,input voltage 12～24V,current 4～20m A,the power supply has voltage self-monitoring protection function,the main control control periodically output 1.2V,1.3V,1.8V and 3.3V four voltage.3d B microstrip multibranch directional coupler is designed because of the common transceiver antenna.Rf board design,including the main chip circuit,memory circuit,power filter circuit and PCB design.System hardware testing,including power supply board voltage output and rf board power on calibration time and cycle time testing.(3)The system software program is realized.Firstly,the flow chart of the whole system software program is given,the subroutine of IWR1843 to obtain configuration parameters and the subroutine design of the system in normal measurement mode are given.Then the configuration and testing of the transmitted waveform.Measures to improve ranging accuracy,multiple chirp coherent accumulation and rife interpolation program implementation.In the system test,there are blind area test,validity test of different range ranging,stability and ranging accuracy test,etc.The test results show that the ranging system has basically realized the high precision ranging requirements and reached the actual use standard. |
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