Research On The Three Dimensional InISAR Imaging Algorithms For The Ship Target With Complex Motions

When the three-dimensional(3-D)interferometric inverse synthetic aperture radar(InISAR)imaging technology is used for the 3-D imaging of the ship targets in the case of full-aperture echos and sparse-aperture echoes,the traditional imaging algorithms are not suitable because of the target echo signals received by the radar will be more complicated during the imaging time as a result of the ship targets have the characteristics of large volume and complex motion.Therefore,according to the characteristics of the ship target echo signals,by combining with the 3-D InISAR imaging technology,this paper proposes a series of effective algorithms to realize the 3-D reconstruction of the ship target with full-aperture echoes and sparse-aperture echoes by using the time-frequency analysis techonlogy and compressed sensing(CS)technology,respectively.Firstly,the specific form of the ship target echo signal is deduced in detail.In order to extract the image-related part of the echoes,the motion compensation and image coregistration of the echoes received by each radar are analyzed in this paper.According to the principle of the 3-D InISAR imaging of the general targets,the basic theory of the 3-D InISAR imaging of ship target with complex motion is described in this paper.Furthermore,this paper deduces the specific from of the ship target echo signals after motion compensation and image coregistration during the long imaging accumulation time,and proposes the 3-D InISAR imaging technology of the ship targets based on the fractional Fourier transform(FRFT)and joint cross S-method algorithm,respectively.Then,in view of the fact that there will be some random missing sampling(RMS)and gap missing sampling(GMS)echoes,this paper studies the motion compensation algorithms for the sparse aperture echoes,including the envelope alignment method of minimizing the entropy of the global average one-dimensional range profiles,the minimum entropy phase correction method,the fast minimum entropy phase correction algorithm and the feature vetor phase correction method.At the same time,the joint minimum entropy phase correction algorithm is usaed to realize the image coregistration of the sparse aperture echoes.And the 3-D InISAR imaging algorithm of the ship target with sparse aperture is proposed when the target is approximately stationary during the imaging time.Finally,for the gap missing echoes are a splicing of several short-aperture echo data blocks,the sigle aperture echo is discussed first in this paper.The imaging accumulation time of the target is short when the radar receives short-aperture echoes.In this paper,based on Bayesian compressive sensing technology,a 3-D InISAR imaging technique based on the logarithmic laplace priori Bayesian and the variational Bayesian algorithm for ship target with short-aperture echoes is proposed.In addition,for the received echoes with random missing sampling and gap missing sampling during the long imaging time,the gradient decent algorithm is adopted to sparsely reconstruct the missing echoes,and then the parameter estimation method is used to achieve the 3-D InISAR imaging of the ship target with sparse aperture.