Acoustic sensor systems on the ground and/or in the air can be used effectively for autonomous and remote intelligence surveillance and reconnaissance (ISR) applications. Acoustic sensors can be used as primary sensors and/or secondary sensors to cue other higher-resolution sensors for detection, tracking and classification of continuous and transient battlefield acoustic events such as ground vehicles, airborne aircraft, personnel, indirect fire, and direct fire. Current collaborative research activities at ARL in acoustic sensing from mobile ground platforms such as HMMWVs and small robotic vehicles [P. Martin and S. Young, Proc. of SPIE Defense & Security Symposium, 2004] and from aerial platforms such as UAVs and balloons [Reiff, Pham et al, Proc. of the 24th Army Science Conference, 2004] demonstrate practical performance enhancements over fixed ground-based platforms for a number of ISR applications. For both mobile ground and aerial platforms, self-generated noise (flow noise and platform noise) is problematic but they can be suppressed with specialized windscreens, sensor placement, and noise cancellation technology. Typical acoustic detection and processing results for mobile platforms are compared and contrasted against fixed ground-based platforms.
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