The Design Of FMCW Radar Water Level Gauge

The water level gauge is an indispensable key in hydrological monitoring.The traditional water level measurement methods mainly include the following: water level scale,ultrasonic ranging and laser ranging,but they all have the disadvantages that the measurement accuracy is susceptible to the environment.With the development of radar technology,the FMCW(Frequency Modulated Continuous Wave)radar ranging method has been paid more and more attention because of its high measurement accuracy,simple structure,small size,low cost,and no measurement blind zone,which becoming a domestic and foreign research hotspot in recent years.Based on the current application requirement of FMCW radar water level gauge,this paper designed a FMCW radar water level gauge based on DSP28335,proposed the overall design scheme,designed related hardware and software systems.Finally,the various functional modules of the entire system were tested.The main research works of this paper are as follows:(1)This paper investigated the current research status of FMCW radar ranging at home and abroad,summarized the development trend and existing problems at home and abroad,proposed the research objectives of this paper,and determined the research contents.(2)The working principle of FMCW radar,the principle of sawtooth wave ranging and the factors affecting the ranging accuracy of FMCW radar are studied.On this basis,the overall design scheme is determined.(3)The hardware design scheme and device selection of the system are determined.The 32-bit floating-point controller DSP28335 is selected as the core processing module,and the IVS-167 radar sensor of InnoSent Company of Germany is selected as the radar module of the system.(4)The linearity correction methods of voltage controlled oscillator(VCO)are studied and compared,and the open-loop correction method is chosen based on cost,complexity and system requirements.After calibration,the linearity of the VCO is significantly improved,and the linearity is increased from 4.5% to 0.126%.(5)The processing algorithms of FMCW radar differential frequency signal are introduced.The FFT algorithm,Zoom-FFT algorithm and CZT algorithm are simulated and compared.The simulation results show that the frequency resolution of CZT algorithm is less than 1Hz.(6)The hardware and software system of the system are completed.The hardware modules are tested.The upper computer interface is designed by using the GUI tool of MATLAB software.Finally,the test platform of FMCW radar water level gauge is built.The test results show that the overall measurement error of FMCW radar water level gauge is 4.8cm within 30 m,the measurement accuracy is 0.16%,and the overall measurement error is 1.4cm within 15 m,and the measurement accuracy is 0.093%.Meet the requirements of the general water level gauge for measurement accuracy.