The Study Of Short-range Moving Target3-dimensional ISAR Imaging

Inverse synthetic aperture radar (ISAR) imaging technology has attracted wideattention since its inception. The range resolution of ISAR imaging is obtained bytransmitting a broadband signal. The lateral resolution depends on the relative rotation ofthe radar and the target. It is easy to get the high quality ISAR image for cooperative ornon-maneuvering objective[1]. However, targets are usually non-cooperative targets ormotor targets, the rotation angle is not available, and so it is difficult to get the transverseproportion of ISAR. For maneuvering target the rotation axis and the rotation speed to theradar is time-varying, which means that the Doppler value is time-varying, likely at thistime the range-Doppler plane is not consistent with the traditional range-Doppler plane. Itwill lead to difficulties in target recognition. At the same time, the two-dimensional ISARimaging technique can only get the projection of target in the range-Doppler plane, wecannot get the real location of the target scattering points, and we also cannot determinethe actual physical size of target. For the field of the radar imaging and target recognitiontechnology development, the traditional two-dimensional ISAR imaging technology hasbeen unable to meet the requirements of the radar imaging and target identification.Because of the lack of the traditional two-dimensional ISAR imaging technology,people begin to put attention to the technical field of three-dimensional ISAR imaging.Interferometric ISAR (InISAR) is proposed earlier as a kind of3D ISAR imagingtechnique[2]. Interference technique was first proposed by Graham, and is used forsynthetic aperture radar (SAR) imaging. Using two interferometric antenna, bycomparing the phase difference of two echo signal, to realize the measurement of theterrain height information[2].The target introduced above is in the far field, when the target is in the far field, theradar wavefront can be processed by Fresnel approximation. The wavefront can be approximated as plane wave. When the target is located in the near field, we should notuse Fresnel approximation. The wavefront can be not processed by plane waveapproximation, which should be calculated according to the spherical wave, while theconventional range and azimuth orthogonal decomposition does not apply in thissituation. However the ISAR processing routine is still feasible, first on the target echomotion compensation, and then gets the target image by using the short-range turntablemodel. As a method in the field of radar imaging, ISAR imaging is an important part ofspace target detection and recognition system. At the same time, the3D ISAR imagingtechnique can establish3D model of space target. It can obtain the physical dimension ofspace target and the spatial position information. What’s more, the three-dimensionalmodel is not impacted by the characteristics of the target. Therefore, how to get the spacetarget3D ISAR imaging method with high efficiency is particularly important. Theresearch on space target three dimensional ISAR imaging technology also has thepractical application significance. This paper mainly studies the method of threedimensional ISAR imaging of short-range moving target. According to the characteristicsof spherical wave, we apply the method of wavefront reconstruction of2-D image oftarget, and then get the3-D information by using the method of interferometricprocessing, and then we can get the three dimensional image of target.The first chapter of this paper is introduction. After a brief introduction of ISAR, thispaper describes the basic concepts of ISAR imaging. Reviews the development of ISARsignal processing technology, and then introduces the research background and the mainwork of this paper.The second chapter introduces the conventional method of ISAR imaging. Mainlyintroduces the range-Doppler algorithm, and then introduces two kinds of pulsecompression algorithm namely matching filter method and dechirping method. And thenintroduce the turntable model of ISAR imaging, the Range-Doppler algorithm and ISARmotion compensation method. At last the simulation shows the limitations of traditionalISAR imaging method when it is used for short-range target imaging.The third chapter introduces the three dimensional imaging technology. First introduces the InISAR basic theory, including InISAR imaging method, InISAR imagingflow, the angular glint and the judgment criterion. And then introduces the imagemismatch and the judgment criterion.The fourth chapter mainly proposes the three dimensional ISAR imaging method forshort-range moving target for the research scene of this topic. Introduces the wavefrontreconstruction method applied to short-range two dimensional imaging. The thirdcoordinate information is obtained by the interference treatment, and then the threedimensional image of target can be obtained. The simulation experiment proves theeffectiveness of this method.The fifth chapter is the conclusion, describes the summary of this paper and theprospect of the future work.