| 摘要 |
<p>An emergency alarm system for detecting smoke in remote areas and for transmitting an indication of detected smoke, either via communications channels already within a facility being protected or by way of telemetry to an alarm indicating device. A fault detector is also provided for indicating when any component of the system becomes defective or otherwise nonfunctional. More specifically, a plurality of smoke detectors of the ion chamber type are positioned at strategic points within a facility to be protected. When any one of the smoke detectors is appropriately activated by smoke, an output in the form of a time duration modulated ultrasonic signal is generated, which is coupled via telemetry or communications channels within the facility being protected to a responder unit which is provided at a central location. If the generated signal persists longer than a predetermined time, an alarm indicator is energized to indicate that smoke is present at one of the smoke detectors. If a fault occurs, such as when one of the smoke detectors becomes disconnected, no ultrasonic signal will be generated and transmitted over the communications channels and, accordingly, a slave timer in the responder unit will not be appropriately deactivated, thereby causing a signal which energizes a fault indicator.</p> |
