An iterative approach for moving target detection and geolocation in SAR

We propose a novel approach to focus and geolocate moving targets in synthetic aperture radar imagery. The initial step is to detect the position of the target using an automatic target detection algorithm. The next step is to estimate the target cross-range velocity using sequential sub-apertures; this is done by forming low resolution images and estimating position as a function of sub-aperture, thus yielding an estimate of the cross-range velocity. This cross-range estimate is then used to bound the search range for a bank of focusing filters. Determining the proper velocity that yields the best focused target defines an equation for the target velocity, however both components of the targets velocity can not be determined from a single equation. Therefore, a second image with a slightly different heading is needed to yield a second focusing velocity, and then having a system of two equations and two unknowns a solution can be obtained. Once the target velocity is known the proper position can be determined from the range velocity. Synthetic data will be used with a point source target and both background clutter and noise added. The results support the development of staring radar applications with much larger synthetic aperture integration times in comparison to existing SAR modes. The basic idea of this approach is to trade-off the development of expensive phased-array technology for GMTI applications with the potential development of advanced processing methods that show potential for processing data over very large aperture integration intervals, to obtain similar GMTI geolocation results that would be compatible with current radar technology.