Security control system

Patent 4755792 Issued on July 5, 1988. Estimated Expiration Date:

August 24, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

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Inventors

Assignee

Black & Decker Inc.

Application

No. 07/089029 filed on 08/24/1987

US Classes:

340/538, Combined with power line340/309.16, Timer control340/309.8, Separate diverse device activated by timer340/506, Alarm system supervision340/527, Time delay340/531, With particular coupling link340/534, Coded message340/538.12, Noise reduction (e.g., filtering)340/538.13, Zero crossing340/538.17, With coupling plug340/539.1, Radio340/547, Magnetic sensor340/825.52Addressing

Examiners

Primary: Crosland, Donnie L.

Attorney, Agent or Firm

Harness, Dickey & Pierce

International Classes

G08B 25/01 (20060101)
G08B 25/06 (20060101)

Abstract

A security and control system for use in a home or building which utilizes a coded audio link between the entry detectors/transmitters and the relay modules, and a digital pulse coded power line communication ("PLC") link between the relay modules and the system controller as well as between the system controller and the various remotely located slave units which control the energization of lamps, appliances, and alarms. The relay modules and controller include constant false alarm rate ("CFAR") receivers 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 at selected points in the AC waveform. The location of each carrier frequency pulse relative to the 60 Hz AC line cycle determines the digital value of the pulse. Both before and during a PLC message transmission, the controller and relay modules are adapted to check the status of the AC power line for the presence of intelligence or excessive noise levels and delay transmission if either condition is detected. In the security mode, the system has three major states: INSTANT-ARM, ARM-DELAY, and DISARM. In the INSTANT-ARM state, the system responds immediately to the detection of an intrusion event. In the ARM-DELAY state, a 40-second delay is implemented before alarm action is taken to permit an authorized entrant to DISARM the system. Significantly, the 40-second delay is implemented by each of the remotely located slave modules so that destruction of the controller by an intruder within the 40-second period will not defeat the system.