The Research On Retrieving Sea Surface Current From X-band Marine Radar

With the development of marine resources,the marine activities of mankind are becoming more and more frequently.The demand for marine monitoring technology has been increasing,and the marine remote sensing technology based on X-band radar emerged.Compared with the traditional methods of ocean monitoring,the monitoring method based on X-band radar has the advantages of low maintenance cost,convenient use,high real-time and high spatial resolution,and has great research value.In this paper,based on the actual research projects,the X-band radar based ocean current inversion technology is studied.In this paper,the development status of sea state parameter inversion based on X-band radar is introduced,and the basic principle of ocean current is analyzed.Focusing on the ocean current inversion algorithm based on X-band radar,the radar imaging principle,the influence of various modulations,the dispersion relation equation and some other related concepts involved in the process are introduced.A deep study of the key issues such as the design of the band-pass filter,the inversion algorithm,and the influence of environmental parameters on the inversion is conducted.Because X-band radar sea clutter images inevitably contain a lot of noise which affects the precision of ocean current retrieval during the acquisition process,and the noise affects the precision of ocean current retrieval,it is necessary to separate the noise from the ocean wave spectrum.According to the characteristics of the wave spectrum,the band-pass filter for wave spectrum is designed.In this paper,the existing filter algorithm is analyzed in depth,and an improved method is put forward to solve the current problems.The feasibility of the method is verified,which paves the way for the subsequent ocean current inversion.In this paper,the three current inversion methods are introduced in detail.The principle,the main problems and defects,and the improvements compared with the former are analyzed in a progressive way.Then the proposed filtering method is added to the existing inversion algorithm and the inversion process is improved.The accuracy and stability of the improved algorithm,are verified by the measured X-band radar sea clutter data.Due to the randomness of the sea surface,the inversion accuracy of ocean currents may be affected by environmental parameters.In order to verify the accuracy of general inversion under different environmental parameters,the sea clutter image is simulated in this paper.The image sequences required by the contrast experiment are obtained by adding different environmental factors.The traditional inversion algorithm and the improved algorithm are used to calculate the simulation data,and the results are compared with each other.At the same time,the influence of different environmental parameters on the algorithm is analyzed.And further verify the feasibility and effectiveness of the improved algorithm in complex environment.