Design Of Ship Draught Measurement System Based On Frequency Modulated Continuous Wave Radar

With the continuous development of the shipping industry,the state has vigorously promoted the development of shipping into an intelligent era,and ship automation is an indispensable part of the development of ship science and technology.In order to avoid objective and subjective errors caused by manual visual methods as much as possible,and the frequency modulation continuous wave radar has high precision and small external interference,it is feasible to design a ship draft measurement system based on frequency modulated continuous wave radar.The specific content of this article is as follows:(1)The overall design of the system.A ship draught measurement system based on frequency modulated continuous wave radar is designed to measure the draught value of the ship.When the draught value of the ship is abnormal,the alarm mechanism is triggered.The paper analyzes the basic functions,system performance and main technical parameters of the measurement system,and designs the overall implementation of the system software and hardware.(2)Radar front-end system design.In order to obtain a stable target difference frequency signal,a radar front-end system is designed,including modulation signal generation circuit,high-pass filter circuit,amplification bias circuit,low-pass filter circuit and limiting voltage emitter follower circuit.In order to further suppress the leakage of the modulation signal,a triangular wave low-pass filter is designed.The filtered output waveform hardly affects the frequency modulation linearity of the FM continuous wave radar.(3)Difference frequency signal data processing.In order to extract the frequency information in the target difference frequency signal,a fast Fourier transform algorithm is applied,which effectively reduces the spectrum leakage problem by windowing.The chirped Z-transformation algorithm is used to perform spectral refinement on the frequency band of interest,reducing the measurement error caused by the fence effect.Considering the influence of wind wave and ship vibration on the measurement accuracy of the system,the maximum amplitude spectrum appearing in the spectrum of the up-and-down frequency modulation frequency of the difference frequency signal is extracted as the paired line of the useful target to realize the spectrum pairing of the measurement target,and then the measurement data collected during a system measurement cycle is smoothed to obtain the ship's draft value.The feasibility of the algorithm is verified by simulation.Finally,the computer software was designed to realize the data processing of the A/D conversion value of the difference frequency signal transmitted from the serial port of the lower computer,and set a friendly and easy-to-operate human-computer interaction interface.(4)System testing.The system was built and the static target was systematically tested.The measurement error rate was kept within 0.5%.The error analysis was carried out and an improved scheme was proposed.