A Study Of TOPSAR Imaging And SAR-GMTI Clutter Suppression

Ground moving target indication(GMTI) technology is a very important part in spaceborne Synthetic Aperture Radar, in order to achieve ground moving target detection, the spaceborne SAR-GMTI system needs to work in a look down state. In this case the radar system will receive echo signals from the ground, including stationary ground clutter and moving targets. The velocity of spaceborne platform is very high, resulting in clutter spectral broadening and energy of stationary ground clutter being stronger than that of moving targets, in which case if traditional methods are continue being used directly, the detection probability will be very low. So in order to improve the detection probability, spaceborne synthetic aperture radar system must have a strong clutter suppression capability, which is a prerequisite to achieve GMTI function.This thesis mainly focuses on spaceborne GMTI performance, TOPSAR imaging and spaceborne three-channel SAR-GMTI adaptive clutter suppression. The main work is summarized as follows:(1) From the relevant indicators of GMTI itself, first to introduce the probability of false alarm and detection probability, minimum detectable velocity. Then introduce the demand of spaceborne SAR-GMTI for clutter environment in the background of nonuniform clutter. Finally, the impact of the coherence property on GMTI performance is introduced, the study of relationships between coherence and clutter rejection and the vertical baseline causing the coherence of GMTI are mainly focused.(2) To analyze the working principle of TOPSAR at first, including the analysis of signal and working mode. On this basis, TOPSAR imaging algorithms are studied, a new scaling method is used, namely BAS algorithm. The simulation results and raw data processing of which show that this method is effective.(3) The three-channel spaceborne SAR-GMTI adaptive clutter suppression is studied.Firstly, multi-aperture techniques are introduced, then the concept of multi-aperture and multi-aperture SAR-GMTI processing methods are discussed in detail. Secondly, on the basis of the traditional clutter suppression methods, a new method is proposed, which considers the correlation of adjacent Doppler unit, and the simulation results show the effectiveness of this method.