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This paper consists of two parts. The first addresses the formation of 2-D high resolution ISAR images of targets such as aircraft and other vehicles without a priori knowledge of target trajectory. The same procedures provide SAR imaging without electromechanical platform stabilization. Two data- adaptive self-calibration algorithms that perform beamforming and focusing are described. The radio camera is the self-calibrating phased-array instrument used. X-band, 150 MHz bandwidth images are presented.
The second part shows that SAR detection sensitivity is considerably enhanced when stereo pairs of such images are presented to the operator. Experiments are described using radar data of a commercial airplane for the target, and fields of farmland for the clutter background. The images of each stereo pair differ only in the horizontal locations of the targets relative to the clutter. Each experiment was viewed by eight observers. The probability of target detection (Pd) vs. target to clutter ratio (TCR) was measured in the first experiment, in which the stereo viewer was an old-fashioned hand-held stereoscope. The use of stereo pairs, relative to single-image viewing, increased detection sensitivity by 7 dB. In the second experiment the stereoscope was replaced by a sophisticated computer-driven electronic display and the threshold of target detectability was measured. The increase in detection sensitivity, again relative to single-image viewing, varied between 20 and 40 dB. The anticipated gain under nonlaboratory conditions is the order of 20 dB.
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