MULTIPLE SENSOR FIRE ALARM SYSTEM MULTIPLE SENSOR FIRE ALARM SYSTEM

摘要

An annunciator system includes a plurality of sensors for sensing an emergency condition. A plurality of transmitters are each operably associated with one of the sensors for transmitting a radiofrequency (RF) signal in response to an alarm signal from the sensor. Each individual transmitter includes a surface acoustic wave (SAW) generator for generating the coded RF signal. A microprocessor-based receiving unit is remotely disposed from the transmitters and is operably associated with an outgoing telephone line. Upon receipt of a signal from one of the transmitters, the receiving unit activates a telephone dialer to send an alarm message to a central monitoring station. The alarm message is preferably in the form of DTMF (dual tone multifrequency) signals. The receiving unit has various features which reduce the possibility of jamming by transmissions from a single transmitter. Also, the transmitter is constructed to draw power from the alarm sensor's battery only when the sensor is producing an alarm signal. N:15661876.CAN