Research On Ground Moving Targets Detection Method Based On UWB SAR Sub-Aperture Iamges

To develop the UWB SAR system, and enhance it with GMTI function we can obtain UWB SAR/GMTI system. It is capable of surveillance, reconnaissance and imaging of wide area ground targets stationary or moving, both in the open or concealed by foliage or in mountainous area, thus can provide the static and dynamic information in complex battlefield.The generation algorithm of UWB SAR sub-aperture image lays the foundation for the two UWB SAR ground moving target detection methods. In this paper, the signal processing procedure from UWB SAR sub-aperture echo to image in frequency domain is analyzed. Then two generation algorithms are discussed and compared: band-pass-during-imaging sub-aperture image generation algorithm and post-band-pass sub-aperture image generation algorithm. For the former one, an algorithm combined with NCS imaging procedure is presented, with its advantage and realization analyzed. In the simulation experiment, this algorithm results in a more accuracy and the same calculating load, compared to which with CS imaging procedure.A type of ground moving target detection method using change detection based on single-channel UWB SAR system is presented, including sub-aperture pair CCD method, sub-aperture series CCD method, sub-aperture pair ICD method and sub-aperture series ICD method. The large beamwidth of UWB SAR enables subdividing the accumulating aperture to several sub-apertures to form a series sub-aperture images indicating different ground view-angles. The moving target focuses on different positions in accordance with the centers of the sub-apertures, while the stationary one remains the same. This type of methods makes use of this difference to realize detection. A series change detection procedure is proposed. This paper also discusses some problems arising in the realization of the algorithm, including choosing strategy of sub-aperture, parameters estimation and design of detector.As for a dual-channel UWB SAR system, a multi-sub-apertures ATI algorithm is proposed. The traditional ATI algorithm only detect moving target with radial velocity, while the novel approach overcomes this limitation and can be effective for moving target with velocity in azimuth or (and) range. The large beamwidth and low frequency of UWB SAR is exploited to generate a series of dual-channel sub-aperture SAR images, which then are processed with ATI in pair with the same view-angle. Integrating these multi-sub-aperture interference images can detect the moving target and estimate its two-dimensional velocity and position. A procedure of multi-sub-aperture ATI algorithm is also presented. We study some problems such as registration, interferometry, defocusing and association of moving target, and put forward solving schemes.All the algorithms proposed above are validated by simulated or half-real data.