Research On Ship Wake Inversion Based On SAR

The ship wake is detected by SAR(Synthetic Aperture Radar),get information about the wake.The navigation state of the ship is calculated according to the information obtained.In the marine environment,moving ships are detected,identified,classified and tracked.Mastering the navigation information of ships is an essential technology for a maritime power.It is not only the navigation security of civil ships,but also of great significance to the military.Based on the theory of fluid mechanics,the mechanism of wake formation is analyzed and the mathematical model is established.Including the establishment of wave spectrum model.According to the principle of SAR,the wake of the ship is imaged and detected,and the data needed for wake inversion are obtained.The main contents are as follows:1.The ship wake model is established.Firstly,based on the theory of fluid mechanics,the wake model is studied.Based on this model,the three-dimensional wake simulation results of 15 ships with different geometric sizes at speeds of 5.14m/s,10.28m/s and 15.42m/s are obtained.The results show that the ratio of hull length to width is positively correlated with the wake wave height;Secondly,the PM spectrum is used to complete the establishment of the wave model,and the wave simulation is carried out when the wind speed is 3m/s,9m/s,12m/s.through the interaction between the wake wave and the sea background wave,it is found that the sea background wave covers the ship wake when the wind speed is 9m/s,making it invisible.2.SAR simulation detection and parameter inversion of ship wake.Firstly,the ship wake is imaged by S AR,and the ship wake data is obtained and the two-dimensional image is generated to obtain the ship wake wavelength data;Secondly,the wake wave height is measured by SAR altimeter;Finally,after the three-dimensional information of the wake is obtained,the ship’s sailing speed and hull aspect ratio are calculated by knowing the ship’s sailing state information,wavelength and wave height,and the error analysis of the retrieved sailing speed and hull aspect ratio is carried out.The results show that the absolute error of the retrieved ship speed of five ships is less than 0.6,and the relative error is less than 6%,The absolute error of inversion hull aspect ratio is 0-0.22,and the relative error is 0-3.55%;The effectiveness of the inversion method is verified.