Research On SAR/ISAR Imaging Algorithm Of Moving Ships

Radar imaging technology is a breakthrough achievement in the field of modern detection science.The emergence of imaging radar expands the concept of traditional radar,making it possible to detect and recognize moving targets and regional targets by imaging.According to the relative movement of imaging radar and target,radar imaging is divided into synthetic aperture radar(SAR)imaging,inverse synthetic aperture radar(ISAR)imaging,and hybrid SAR/ISAR imaging.The SAR imaging results of the ship usually appear serious blur and defocus due to the complex ship motion caused by the interaction with sea surface.Therefore,based on the hybrid SAR / ISAR imaging method,this paper mainly study the imaging problems of airborne radar to moving ship target.The main tasks as follows: 1.Analying the basic principles of SAR and ISAR imaging.Both of them are aim to obtain high resolution in the range direction by compressing the chirp signal with a large timebandwidth product.SAR / ISAR imaging provides theoretical support.2.Study on the SAR imaging simulation method of static ship targets.Based on the verification of the range Doppler algorithm(RD)and linear frequency modulation(CS)imaging algorithm,the electromagnetic scattering coefficient of the complex ship model is calculated using physical optics,which is combined with the parameters of the airborne motion radar to simulate the proximity The measured echo signal data is applied to the range Doppler(RD)imaging algorithm to obtain the static SAR imaging result of the ship target.3.Study on ship target motion compensation and ISAR imaging algorithm.For the translational component,the motion compensation and imaging simulation are carried out using the minimum entropy method and the phase gradient autofocus method;for the rotation component,the ship echo signal model is reconstructed by the three-dimensional rotation component,combined with time-frequency analysis,the movement ship is realized Distance instantaneous Doppler imaging.4.Based on the SAR / ISAR hybrid imaging algorithm,the high-resolution imaging method of airborne radar for moving ships was researched.By analyzing the effects of target and radar motion on echo signals,instantaneous slant distance,and Doppler parameters,the principle and steps of SAR / ISAR hybrid imaging of moving targets are given.The targets are moved in range and azimuth.Imaging simulation is implemented,and the ship target with non-stationary motion is used to perform instantaneous distance Doppler imaging after time-frequency compensation using time-frequency analysis method.In addition,when there are multiple ship targets on the sea at the same time,the relevant data of the target ship is intercepted in the scene SAR imaging data,and the captured ship data is subjected to ISAR imaging processing to obtain a SAR / ISAR hybrid of a multi-target moving ship The imaging results and simulation results prove the effectiveness of the imaging algorithm.