| 摘要 |
Apparatus and methods for estimating the cross-range scale factor for a displayed inverse synthetic aperture radar image using received image data. The image data is first converted into a polar format. The image data is then processed by a two-dimensional Fourier transform filter to produce a plurality of image entropy estimates. The best image entropy estimate is selected, and then a cross-range scale factor is computed from the data associated with this estimate. This cross-range scale factor is then displayed on a display, from which an operator can accurately determine the size of target objects imaged by the radar. This, in turn provides for identification of the target objects. More specifically, by using polar-format processing, and by selecting the best image obtained for assumed values of rotation rate of a target object, an accurate estimate of the cross-range scale factor is obtained. The present method enables estimation of the length of a target object from it's image and thus provides for rapid identification of the object using the displayed length estimate.
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