Abstract: A handheld, battery-operated prototype of a remove concealed weapons detector has been built and tested. The concealed weapons detector will enable law enforcement and security officers to detect metallic and nonmetallic weapons concealed beneath clothing remotely from beyond arm's length to about 20 feet. These detectors may be used to: (1) allow hands-off, stand-off frisking of suspects for metallic and nonmetallic weapons; and (2) search for metallic and nonmetallic weapons on cooperative subjects at courthouse entrances and other monitored security portals. We have demonstrated that we image weapons concealed under heavy clothing, not just detect them, at ranges up to 15 feet using the same ultrasound frequency (40 kHz) used by commercial rangefinders. The concealed weapons detector operates much as a rangefinder, but at higher peak fluxes and pulse repetition frequencies. The detector alerts the user to concealed weapons audibly and visibly by detecting ultrasound glints above a body/clothing baseline, and by compensating for changing range and attenuation. The detector locates concealed weapons within a 6-inch illuminated spot at 10 feet. The signal processor eliminates any signal from behind the target.!8
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