Wireless closed loop alarm system - uses digital signals with ROM-controlled code and two transceivers with logic circuitry

摘要

A wireless loop alarm system includes two transceivers with logic circuitry. The first transceiver includes a clock generator feeding a pulse counter and r.o.m. The modulated output is also fed to an infra-red transmitter. Signals are received in a receiver, demodulated, and fed to a pulse counter coupled to a second and third ROM. A comparator feeds a further pulse counter, modulator and transmitter. The signals are received and demodulated similarly by a second receiver feeding a comparator. This comparator is coupled to a pulse counter which operates an alarm if the loop is broken.