METHOD FOR SECURITY ALARM Russian patent published in 1997 - IPC

FIELD: automation, in particular, fire and security alarm devices. SUBSTANCE: method involves generation of sign-alternating signal, sending it to final-control unit through loop, which has alarm detectors. The final-control unit generates additional signal which is shaped as pulse series which contains periodic pulses which parameter differs from same parameter of other pulses in this period. Said additional signal is sent to alarm loop. Then device generates information signal which has changed pulse series depending on loop state and alarm detectors which are in loop. Analysis of latter pulse series results in statement on condition of loop and alarm detectors. So described method differs from previous art by operation for generation of additional signal by final-control unit and by feeding said additional signal to loop and by shape of information signal. EFFECT: increased functional reliability. 8 dwg