Electronic monitor for antitheft alarm system for protected zone - uses pulse sequence generator feeding key in form of diode matrix from which binary code is decoded to detect unauthorised entry attempt

摘要

The alarm/monitor system operates on the basis of a pass-word in the form of a predetermined code in an electronic circuit, and uses a sequence generator which sends a train of pulses to three different inputs of a terminal comprising a diode matrix. The terminal transforms the sequence, which is in the form of three pulses, into three binary data bits which are sent to a decoder. The decoder is connected to an electronic lock which inhibits an alarm generator. When a wrong sequence is fed into the decoder from the diode matrix, the alarm generator is activated. In a protection zone, each user has a terminal which effectively acts as a key.