Pseudo—random state mechanical switch

Abstract

A method for detecting entry into a secure area uses a passive entry detector. The secure area has an access door, having a closed position. The passive entry detector comprises a source of energy internal or external to the passive entry detector, an activator for detecting a change in the access door from its closed position, and for releasing the energy in response to the change of the access door from the closed position. The energy is transferred to one or more pseudo random units. Each of the pseudo random units has a plurality of mechanical states. The pseudo random units are responsive to the activator. The activator induces a change of the mechanical states in the pseudo random units upon transfer of energy. The pseudo random units report the mechanical states upon interrogation. Using above passive entry detector, a first interrogation using the interface is performed to create a first record to identify one or more mechanical states with the access door in the closed position. Re-interrogating is performed again after an interval, typically prior to opening the access door from its closed position. This re-interrogating identifies again the mechanical states in the pseudo random units of the passive entry detector and generates a second record. Comparing the first record with the second record determines if the internal mechanical states have been altered during the time interval.