Target-aided compression of SAR imagery for transmission over noisy wireless channels

In this paper, we present a target-aided, error-resilient system for coding synthetic aperture radar (SAR) imagery, whereby regions of interest and background information are coded independently of each other. A multiresolution constant-false-alarm-rate (CFAR) detection scheme is utilized to discriminate between target regions and natural clutter. Based upon the detected target regions, we apply less compression to targets, and more compression to background data. This methodology preserves relevant features of targets for further analysis, and preserves the background only to the extent of providing contextual information. The resilience to channel errors is obtained without the use of channel coding or error concealment techniques. The robust nature of the coder eliminates the appearance of impulsive channel-error-induced artifacts in the decoded imagery, while increasing the security level of the encoded bit stream. The proposed coder is evaluated in terms of target detection performance on the decoded SAR image for a wide variety of channel conditions and encoding bit rates. The resulting system dramatically reduces the bandwidth requirements of the digital SAR imagery, and is shown to provide outstanding performance in adverse channel conditions.