(57) 0 A security and control system for use in a home or building, utilizes a coded audio
link between entry detectors/transmitters (12) and relay modules (18), and a digital
pulse coded power line communication (PLC) link between the relay modules (18) and
a system controller (20) as well as between the system controller (20) and various
remotely located slave units (22, 24, 26) which control the energization of lamps,
appliance, and alarms. The controller (20) is also adapted to receive coded audio
signals directly from an entry detector/transmitter - (12). The relay modules (22,
24, 26) and controller - (20) include constan false alarm rate receiver for isolating
the coded audio signal from background noise, and unique exclusion circuitry for decoding
the isolated signal. The PLC messages are generated by impressing a pulse code modulated
high frequency carrier signal onto the AC line (30) at selected points in the AC waveform.
The location of each carrier frequency pulse relative to the AC line cycle determines
the digital value of the pulse. Both before and during a PLC message transmission,
the controller (20) and relay modules (22, 24, 26) are adapted to check the status
of the AC power line for the presence of either intelligence or excessive noise levels.
When operated as a remote control system, unit codes in the PLC messages transmitted
by the system controller (20) serve to selectively identify particular slave modules
(22, 24, 26). In the security mode, the system has three major states: INSTANT-ARM,
ARM-DELAY, and DISARM.
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