Reduced power supervisory message transmission in a wireless alarm system

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG.
1 illustrates a block diagram of an alarm system 10, which comprises a central receiver control unit 12, a plurality of alarm sensor transmitters 14, and a console 16.
The central receiver control unit 12 is in communication with the plurality of alarm sensor transmitter 14, each of which comprise an alarm sensor and a transmitter.
The alarm sensor transmitters 14 are well known in the art and comprise, for example, motion detectors, fire or smoke sensors, glass breakage detectors, door or window entry sensors, and similar sensors.
In the preferred embodiment, the alarm system 10 operates in a so-called "wireless" fashion by electromagnetic wave transmission (e.
g.
, radio frequency waves) between the alarm sensor transmitters 14 and the central receiver control unit 12.
The transmitters within each alarm sensor transmitter 14 are also well known in the art, and transmit supervisory and alarm messages which modulate a radio frequency signal (e.
g.
, 345 MHz).
The modulated radio frequency signal is received, processed and decoded by the central receiver control unit 12, enabling the central receiver control unit 12 access to be provided with the information contained within the supervisory or alarm message and act accordingly (e.
g.
, by sounding an alarm speaker, dialing the police or fire station, etc.
).
Further detail regarding wireless alarm systems may be found in U.
S.
Pat.
No.
4,754,261 to Marino, which is owned by the assignee of the present invention and is hereby incorporated by reference.
The alarm sensor transmitters 14 are designed to transmit supervisory messages and alarm messages indicating the status of the alarm sensors in accordance with protocols well known in the art.
The supervisory message functions to provide a periodic and continuous Built-in-Test (BIT) capability which ensures that communication between each alarm sensor transmitter 14 and the central receiver control unit 12 is operative.
Since it is possible in this type of system that an alarm sensor transmitter 14 may only transmit an alarm signal during a health, safety or security emergency (e