An electronic random selector for security applications
J.W. Kronberg · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 1991
This paper reports that enhanced DOE security requirements at contractor sites now include random searches of a specified percentage of entering personnel, using a metal detector. An electronic random selector has been developed which is self-contained, rugged, compact, tamper-resistant and easy to operate. Passage of an entering person's hand over a sensor starts an oscillator, which cycles among several electronic states for a few seconds, then stops in one of them and generates an output signal. One of these states signals STOP FOR INSPECTION through a red light and buzzer; each of the others signals PASS -- O.K. through a green light and chime. The probability of selection is inversely proportional to the number of states, which is programmable, and is unaffected by the results of previous cycles. The use of the randomizer eases selection, ensures that it is fair and meets the DOE-specified percentage, and rules out most forms of tampering or subterfuge which might otherwise be used to gain entry without a search. It replaces more traditional but troublesome selection methods, such as the drawing of cards from a holder.