FIRE AND INTRUDER ALARM SYSTEM Russian patent published in 2004 - IPC

FIELD: automatic equipment for control and communication systems, particularly fire and intruder alarms.

SUBSTANCE: system includes technical means which provide regular control of calling device workability (sensor - interface block). Control is carried out by request common for all calling devices and with necessarily unequivocal queue of their replies. Control panel is linked with calling devices through two loop wires and all calling devices are connected in parallel to loop wires, which is possible due to low current (microampere) input of calling device microcircuits. Each sensor is connected to loop wires through its interface block. Interface blocks analyze zero voltage period duration in signal loop wire and take thereof as "request" pulse by predetermined value of pulse duration. After that all interface blocks generate replies as voltage impulses of zero amplitude and transmit replies to signal loop wire with equal calling device duration after time delay. Replies are of determined value for each calling device if calling device is in good order. Analysis of reply impulses of calling devices provides corresponding assessment.

EFFECT: increased reliability.

3 dwg