GMTI Analysis And Processing Of Airborne Measured Data

SAR-GMTI and wide area GMTI are two classical applications of radar systems. A SAR-GMTI or wide area GMTI system not only could acquire the information of stationary scenes, but also could acquire the information, including the velocities and positions, of ground moving targets by utilizing the technology of moving target indication, hence GMTI is badly meaningful to the military and civil area, such as situation monitoring of battlefield, supervisory control of traffic and so on.As for the GMTI systems, stationary scene is regarded as background clutter in which the moving targets are usually submerged, so the key point of GMTI processing is how to realize the clutter suppression. In fact, there exists some factors which is inconsistent with the ideal model in the airborne measured data processing, such as the unsteadiness of the airborne platform, the difference between channels and so on, hence it is necessary to improve the GMTI models and to find out an effective method of moving target indication. In addition, wide area GMTI is an important trend of the MTI technology development, it has a wide observation area, a high revisit rate and a relatively low resolution demand, therefore the research of an effective wide area GMTI method should be conducted. In order to solve the problems stated above, this thesis firstly discusses the echo model of moving targets and the principles of GMTI, then majorly studies the clutter suppression methods of GMTI systems, the processing methods of three-channel airborne SAR-GMTI measured data and two channel wide area GMTI measured data, which are stated in detail below.(1) The echo model of moving targets in the multichannel SAR-GMTI system is given, then some classical methods of clutter suppression and moving target indication are mainly discussed and compared, such as DPCA, ATI and STAP. Considering the stability of DPCA and the high accuracy of ATI, a processing method for airborne SAR-GMTI data is given based on the combination of DPCA and ATI, the results of simulation data processing validates the effectiveness of this method.(2) Based on the analysis of the problems in the processing of multichannel airborne SAR-GMTI measured data, a research of effective motion compensation and channel equalization are conducted and a processing method of measured data is given.Considering the motion errors of the airborne platform, the antenna pattern and position errors, as well as the receiving channel responding errors, this method firstly conducts a motion compensation based on the Doppler modulation rate estimation from the echo data, then performs an iteration compensation of the amplitude and phase errors so as to correct difference between channels. After the clutter suppression by DPCA, a method based on the minimum entropy search is given to get the blur numbers of the moving detected targets, then the velocities and real positions of moving targets could be acquired, and finally a high quality SAR-GMTI result is obtained.(3) By establishing the echo model of moving targets in the wide area GMTI systems, an effective method to realize wide area ground moving targets indication is studied according to the features of wide area GMTI measured data. This method obtain images of each subregion by DBS technology, then appliess an image segments integration based on the fast correlation, and a coordinates transition based on the interpolation processing to the sub-images in order to get a whole image. Clutter suppression and moving targets detection is performed afterwards using DPCA and CFAR, then a moving targets relocation method using interference phase is given, the results of simulation data and measured data processing indicates that this method have a superior performance.