To solve the problem of helping surveillance cameras at busy venues distinguish friendly forces from intruders, Cybernet developed an innovative friend-or-foe detection system using spread-spectrum infrared beacon receivers to be carried by all friendly personnel. The receivers, which are lightweight and inconspicuous, are periodically “awakened” by a spread spectrum beacon from the surveillance system and a response beacon is triggered within 2 seconds. By process of elimination, intruders are revealed. This system was designed to meet client requirements that included direct view (requiring no computation), extreme ease of use, small size, high rate of accuracy, invisibility to enemy forces, and affordability.