US 4,162,488 A · Alarm system

Abstract

An alarm system is disclosed which utilizes the Bell System DATAPHONE (a registered service mark of AT&T Company) Select-A-Station Service equipment to communicate alarm messages from a plurality of protected premises to a central monitoring station. The system includes a plurality of transponder units, one at each of the protected premises, connected to the central monitoring station through the Bell System equipment. The central monitoring station sequentially polls all the transponders. This is accomplished by sequentially setting up connections from the central monitoring station to the transponder units and sending a START tone burst. In response to receipt of a START tone burst, the connected transponder transmits a tone burst reporting the status of the protected premises. This tone burst contains six tone-pairs in defined time slots, each of the tone-pairs identifying the condition of an associated protected zone, AC power status, and whether the protected premises is in its DAY or NIGHT mode. An alarm condition causes the absence of a tone-pair associated with the particular protected zone. The central monitoring station monitors for the absence of tone-pairs and if two out of three consecutive polls, in their proper turn, of the transponder at a particular protected premises reveal the persistence of an alarm condition, operating personnel at the central monitoring station are alerted so that the proper authorities may in turn be notified. When a DAY to NIGHT transition is requested by a customer at a protected premises, the central monitoring station transmits a RINGBACK tone burst, which is the same frequency signal as utilized for the START tone burst, except that it occurs during a different time interval of the scan time. The central monitoring station includes a memory for storing the status of each of the protected premises, a display, a printer, and associated control circuitry.

Claims28

Dependent claims

An alarm system for monitoring conditions at a plurality of protected premises comprising:

switching means having a primary port and a plurality of secondary ports and responsive to successive appearances of a predetermined signal at its primary port for sequentially establishing connections between said primary port and each of said plurality of secondary ports;
central monitoring station apparatus connected to said switching means primary port, said central monitoring station apparatus including:
means for successively generating said predetermined signal at equally spaced predetermined intervals;
means operative at the termination of each occurrence of said predetermined signal for transmitting a START signal over the connection established by said switching means;
means for detecting predetermined tones received over said connection after the termination of said START signal;
and
means responsive to a tone absence for recognizing an alarm condition;
and
a plurality of transponder units each located at a respective protected premises and each connected to a respective one of said switching means secondary ports, said respective protected premises including a plurality of protected zones, with one or more sensor elements disposed at each of said protected zones for providing status indications of each of said protected zones, each of said transponder units including:
clock means responsive to receipt of said START signal over said switching means connection for defining a plurality of time slots each corresponding to one of said protected zones;
means for transmitting selected ones of said predetermined tones during corresponding ones of said plurality of time slots over said connection;
and
means responsive to an indication from a sensor element of said alarm condition in one of said protected zones for inhibiting the transmission of tons in the time slot corresponding to said one protected zone, so as to produce said tone absence for recognition by said recognizing means in said central monitoring station apparatus.

10 more elements

In an alarm system for monitoring conditions at a plurality of protected premises, which alarm system includes switching means having a primary port and a plurality of secondary ports and responsive to successive appearances of a predetermined signal at its primary port for sequentially establishing connections between said primary port and each of said plurality of secondary ports, and central monitoring station apparatus connected to said switching means primary port, said central monitoring station apparatus successively generating said predetermined signal at equally spaced intervals and transmitting a START signal over the connection established by said switching means,

a transponder unit located at a respective protected premises and connected to a respective one of said switching means secondary ports, said respective protected premises including a plurality of protected zones, with one or more sensor elements disposed at each of said protected zones for providing status indications of each of said protected zones, said transponder unit including:
clock means responsive to receipt of said START signal over said switching means connection for defining a plurality of time slots each corresponding to one of said protected zones;
means for transmitting selected ones of said predetermined tones during corresponding ones of said plurality of time slots over said connection;
and
means responsive to an indication from a sensor element of said alarm condition in one of said protected zones for inhibiting the transmission of tones in the time slot corresponding to said one protected zone.

2 more elements

In an alarm system for monitoring conditions at a plurality of protected premises, which alarm system includes switching means having a primary port and a plurality of secondary ports and responsive to successive appearances of a predetermined signal at its primary port for sequentially establishing connections between said primary port and each of said plurality of secondary ports, and a plurality of transponder units each located at a respective protected premises and connected to a respective one of said switching means secondary ports, each of said transponder units being responsive to receipt of a START signal at its respective switching means secondary port for selectively transmitting predetermined tones in predetermined time slots to said switching means secondary port,

central monitoring station apparatus connected to said switching means primary port, said central monitoring station apparatus including:
means for successively generating said predetermined signal at equally spaced predetermined intervals;
means operative at the termination of each occurrence of said predetermined signal for transmitting said START signal over the connection established by said switching means;
means for detecting said predetermined tones in predetermined time slots received over said connection after the termination of said START signal;
and
means responsive to a tone absence for recognizing an alarm condition.

3 more elements

Dependencies are inferred from the claim text.

Alarm system

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Alarm system

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Abstract

Claims28