Research On Detection And Parameters Extraction Of Marine Internal Waves In High Resolution And Wide Swath SAR

The internal wave of the ocean is an ocean phenomenon with a wide distribution range,so the internal wave needs to be detected with high score and wide range.Synthetic Aperture Radar(SAR)is often used to image the ground and the ocean because it is not restricted by the external environment.The high-resolution wide-area SAR and interferometric SAR,which are extended on the basis of SAR,have also become important loads in ocean detection.Receiving(MIMO)mode to achieve high-resolution wide-area SAR detection imaging has become a research hotspot to obtain large-coverage,high-resolution ocean images,while applying interference processing to obtain ocean dynamic information.This paper mainly designs the spaceborne MIMO-SAR that satisfies the conditions of high-resolution and wide amplitude,and realizes the high-resolution and wide-width measurement and parameter extraction of marine internal waves by MIMO-SAR.The main research contents are as follows:This paper firstly analyzes the effects of different depths and ve locities of underwater moving objects on the amplitude of internal waves by studying and simulating the one-dimensional,two-dimensional ocean internal waves and internal wave models caused by underwater moving objects.Derivation and simulation of random ocean waves,but the relationship between internal waves and random ocean waves is not a simple superposition.Through the analysis and derivation of wave current interaction,the internal waves in the background of random ocean waves are simulated,and the relationship between internal waves and electromagnetic waves is simulated.The mechanism of action is discussed,and the multi-scale scattering model is used to form an electromagnetic scattering model of internal waves.Then,for the spaceborne SAR,study the single-base phased array MIMO-SAR,analyze the radar system parameters and the influence factors of the platform and the environment on the imaging,and discuss the orbital height,frequency,and polarization mode of the spaceborne high-resolution wide-amplitude MIMO-SAR,Lower angle of view,array and pulse repetition period,to achieve the feasibility of wide coverage and high resolution sea detection,analyze the effect of different wind speed,wind direction,and amplitude on the internal wave amplitude in SAR imaging,and give the effect of underwater target depth and speed on imaging Analyze and carry out numerical simulation and pool experiments.The experimental analysis results lay the foundation for high-resolution wide-range imaging.Secondly,the algorithm design of the designed high-resolution wide-band spaceborne MIMO-SAR is carried out.For the waveform design of the high-resolution wide-amplitude MIMO-SAR system,the orthogonal coding waveform based on genetic algorithm is adopted.The fuzzy function obtained by superimposing the orthogonal coding and the chirp signal has the advantages of low side lobe and high range resolution.After separation by orthogonal coding,the azimuth blur is resolved to obtain high-resolution azimuth resolution.Through the uniform multi-beam in the distance direction,the DBF focusing process is realized,and the distance resolution and the peak side lobe ratio are improved.Finally,use the acquired internal wave SAR images to perform empirical mode decomposition,integrated empirical mode decomposition,complete integrated empirical mode decomposition and two-dimensional empirical mode decomposition to extract the internal wave wavelength and compare the extraction results by several methods.The conclusion that the complete integrated empirical mode decomposition has the best decomposition result for the internal wave image of the spaceborne SAR is obtained.The interferometric SAR image is used to extract the wave velocity,and the extraction result is fitted to the original wave velocity to obtain a conclusion that the extraction result is more consistent with the original wave velocity.