APPLYING STAP TECHNIQUES FOR CORRECT POSITIONING OF MOVING TARGETS WITHIN SAR IMAGES

摘要

As is generally known, Synthetic Aperture Radar (SAR) can be applied to gain 2-dimensional clutter maps of the earth's surface. However, only fixed targets are mapped on their correct positions. Moving targets are displaced in az-imuthal direction due to the doppler frequency caused by target velocities. The detection and correct positioning of moving targets within SAR images is a problem that can be solved by using multiple antennas and multichannel receivers. Usually, monopulse is applied to estimate the target's fine azimuthal positions by using phase differences between the receiver channels. Admittedly, phase measurements are biased by phase errors of antennas and receivers. To compensate these phase errors, calibration coefficients have to be determined e. g. by using an on-line correlation analysis of the receiver signals. Such a correlation analysis can be performed e. g. by applying Space-Time Adaptive Processing (STAP). Normally, STAP is used for suppressing clutter and jammers. This paper describes a supplementary application of clutter filter coefficients gained by STAP for the purpose of correct positioning of moving targets within SAR images. The principles of this moving target repositioning technique are explained and results are demonstrated that are gained with real SAR data.