Security control system

• US 4,755,792 A
• Filed: 08/24/1987
• Issued: 07/05/1988
• Est. Priority Date: 06/13/1985
• Status: Expired due to Fees

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Mitasev, Blazo A., Pezzolo, Donald E.
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/089,029
• Time in Patent Office: 316 Days
• Field of Search: 340/538, 340/539, 340/500, 340/506, 340/531, 340/533, 340/534, 340/541, 340/310 R, 340/310 A, 340/310 CP, 340/309.15, 340/527, 340/825.06, 340/528 , 340/825.71, 367/199
• US Class Current: 340/538
• CPC Class Codes: G08B 13/1418 Removal detected by failure in electrical connection between the appliance and a control centre, home control panel or a power supply
• CPC Class Codes: G08B 25/06 using power transmission lines

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.

Claims

1. A security system for detecting an intrusion into a protected premises having an AC power line and signaling the detection of the inrusion event, including:

one or more entry detectors operatively associated with a corresponding number of selected entryways to the protected premises for sensing an entry through said respective entryways and producing a coded audo signal in response thereto;

at least one signal relay device adapted to be electrically connected to the AC power line in the protected premises and located within the audio range of an entry detector, including audio receiver means for receiving said coded audio signal and separating said coded audio signal from extraneous noise in the received signal, PLC transmission means for impressing a coded relay signal onto said AC power line, and processor means for decoding said coded audio signal and enabling said PLC transmission means in said relay device to transmit said coded relay signal in response to the detection of a valid coded audio signal;

a controller adapted to be electrically connected to the AC power line of the protected premises, including PLC receiver means for receiving said coded relay signal and separating said coded relay signal from extraneous signals on said AC power line, PLC transmission means for impressing a coded controller signal onto said AC power line, and processor means for decoding said coded relay signal and enabling said PLC transmission means in said controller to transmit said coded controller signal in response to the detection of a valid coded relay signal; and

at least one slave device adapted to be electrically connected between the AC power line and an alarm device for controlling the activation of said alarm device, including PLC receiver means for receiving said coded controller signal and separating said coded controller signal from extraneous signals on said AC power line, output means for activating said alarm device, and processor means for decoding said coded controller signal and enabling said output means to activate said alarm device in response to the detection of a valid coded controller signal.

2. The security system according to claim 1 wherein said controller means is selectively operable in either a first mode wherein a first coded controller signal is impressed onto said AC power line in response to the receipt and detection of a valid coded relay signal or a second mode wherein a second coded controller signal is impressed onto said AC power line in response to the receipt and detection of a valid coded relay signal.

3. The security system according to claim 2 wherein said processor means in said slave device is adapted to immediately enable said output means to activate said alarm device in response to the receipt and detection of said first coded controller signal and further adapted to enable said output means to activate said alarm device after a predetermined time delay following the receipt and detection of said second coded controller signal.

4. The security system according to claim 1 wherein said processor means in said controller is adapted to determine if other coded signals are being transmitted over said AC power line before enabling said PLC transmission means in said controller to transmit said coded controller signal.

5. The security system according to claim 4 wherein said processor means in said controller is further adapted to wait a random period of time following a determination that other coded signals are present on said AC power line before again attempting transmission of said coded controller signal.

6. The security system according to claim 4 wherein said processor means in said controller is further adapted to determine if noise levels in excess of a predetermined amount are present on said AC power line before enabling said PLC transmission means in said controller to transmit said coded controller signal.

7. The security system according to claim 6 wherein said processor means in said controller is further adapted to wait a random period of time before again attempting transmission of said coded controller signal following a determination of the presence on said AC power line of either other coded signals or noise levels in excess of said predetermined amount.

8. The security system according to claim 4 wherein said AC power line contains an alternating current signal having zero-crossing points in its waveform and said relay coded signal and said controller coded signal comprise predetermined carrier frequency signals that are digitally pulse code modulated relative to the zero-crossing points in the AC power line waveform such that one complete cycle of the AC power line waveform is used to transmit each bit of information in said coded signals.

9. The security system according to claim 8 wherein said pulse code modulated carrier frequency signal is representative of a digital "1" when a carrier frequency pulse is generated during the positive (negative) half cycle of the AC power line waveform and a digital "0" when a carrier frequency pulse is generated during the negative (positive) half cycle of the AC power line waveform.

10. The security system according to claim 9 wherein said processor means in said controller is further adapted to determine if other pulse code modulated carrier frequency signals are being transmitted over said AC power line during the transmission of a controller coded signal by looking for the presence of said carrier frequency on said AC power line during the unused half cycle of the AC power line waveform.

11. The security system acccording to claim 1 wherein said coded audio signal has at least one predetermined frequency associated therewith and said audio receiver means in said signal relay device includes a receiver comprising a broadband bandpass filter circuit, a limiter circuit connected to the output of said broadband bandpass filter circuit, and a narrow bandpass filter circuit connected to the output of said limiter circuit and having a center frequency approximately equal to said predetermined frequency.

12. The security system according to claim 11 wherein said coded audio signal comprises alternating predetermined first and second frequency tones having predetermined spacing between successive alternating tones.

13. The security system according to claim 12 wherein said receiver includes first and second narrow bandpass filter circuits connected to the output of said limiter circuit and having center frequencies approximately equal to said first and second predetermined frequencies, respectively.

14. The security system according to claim 13 wherein said audio receiver means further includes decoding means for decoding said coded audio signal, comprising logic circuit means for detecting in corresponding alternating sequence the presence of said first predetermined frequency tone and the simultaneous absence of said second predetermined frequency tone followed by the presence of said second predetermined frequency tone and the simultaneous absence of said first predetermined frequency tone.

15. The security system according to claim 14 wherein said first and second predetermined frequencies are approximately equal to 6 KHz and 7.3 KHz, respectively.

16. A security system for detecting an intrusion into a protected premises and signaling the detection of the intrusion event, including:

intrusion detection means for detecting an intrusion into the protected premises and producing a coded signal in response thereto;

controller means for receiving said coded signal from said intrusion detection means and producing alarm signals in response thereto, said controller means being selectively operable in either a first mode wherein a first alarm signal is produced in response to the receipt of a coded signal from said intrusion detection means, or a second mode wherein a second alarm signal is produced in response to the receipt of a coded signal from said intrusion detection means; and

slave means located remotely from said controller means and connected to an alarm device for controlling the activation of said alarm device, said slave means being responsive to the receipt of said first alarm signal from said controller means to immediately activate said alarm device and being responsive to the receipt of said second alarm signal from said controller means for implementing a predetermined time delay before activating said alarm device.

17. The security system according to claim 16 wherein said controller means is further adapted to produce a third signal and said slave means is responsive to the receipt of said third signal from said controller means for aborting the implementation of said predetermined time delay and preventing activation of said alarm device.

18. The security system according to claim 17 wherein said controller means further includes input means for permitting an operator to input information into said controller means, and said controller means is further adapted to produce said third signal solely in response to the entry of a secret code established by the operator into said controller means via said input means.

19. The security system according to claim 18 wherein said controller means is selectively operable in either of said first or second modes in response to predetermined entries made via said input means.

20. The security system according to claim 16 wherein said controller means is adapted to be electrically connected to the AC power line of the protected premises and further includes PLC transmission means for impressing said alarm signals onto said AC power line.

21. The security system according to claim 20 wherein said slave means is adapted to be electrically connected between said AC power line and said alarm device and further includes PLC receiver means for receiving said alarm signals transmitted over said AC power line from said controller means.

22. A security system for detecting an intrusion into a protected premises and signaling the detection of the intrusion event, including:

intrusion detection means for detecting an intrusion into the protected premises and producing a coded audio signal in response thereto, said coded audio signal having at least one predetermined frequency associated therewith; and

a device for receiving and decoding said coded audio signal and producing an alarm signal in response thereto, said device including receiver means for separating said coded audio signal from the extraneous noise in the received signal, comprising a broadband bandpass filter circuit, a limiter circuit connected to the output of said broadband bandpass filter circuit, and a narrow bandpass filter circuit connected to the output of said limiter circuit and having a center frequency approximately equal to said predetermined frequency.

23. The security system according to claim 22 wherein said coded audio signal comprises alternating predetermined first and second frequency tones having predetermined spacing between successive alternating tones.

24. The security system according to claim 23 wherein said predetermined spacing is of sufficient duration to insure that the echoes from the transmission of said first (second) frequency tone will have diminished sufficiently by the time said second (first) frequency tone is transmitted so that said echo signals will be excluded by said receiver means when said second (first) frequency tone is received.

25. The security system according to claim 24 wherein said receiver means includes first and second narrow bandpass filter circuits connected to the output of said limiter circuit and having center frequencies approximately equal to said first and second predetermined frequencies, respectively.

26. The security system according to claim 25 wherein said device further includes decoding means for decoding said coded audio signal, comprising logic circuit means for detecting in corresponding alternating sequence the presence of said first predetermined frequency tone and the simultaneous absence of said second predetermined frequency tone followed by the presence of said second predetermined frequency tone and the simultaneous absence of said first predetermined frequency tone.

27. The security system according to claim 26 wherein said first and second predetermined frequencies are approximately equal to 6 KHz and 7.3 KHz, respectively.

28. The security system according to claim 22 wherein said device comprises a signal relay device that is adapted to be electrically connected to the AC power line in the protected premises and includes PLC transmission means for impressing said alarm signal onto said AC power line.

29. The security system according to claim 28 further including:

a controller adapted to be electrically connected to the AC power line of the protected premises, including PLC receiver means for receiving said alarm signal from said signal relay device, PLC transmission means for impressing a controller signal onto said AC power line, and processer means for enabling said PLC transmission means in said controller to transmit said controller signal in response to the detection of said alarm signal; and

at least one slave device adapted to be electrically connected between the AC power line and an alarm device for controlling the activation of said alarm device, including PLC receiver means for receiving said controller signal, output means for activating said alarm device, and processor means for enabling said output means to activate said alarm device in response to the detection of said controller signal.

30. The security system according to claim 29 wherein said processor means in said slave device is adapted to implement a predetermined time delay upon detection of said controller signal before enabling said output means to activate said alarm device.

31. In a security system including detection means for detecting an intrusion into a protected premises having an AC power line and producing an intrusion signal in response thereto, a signal relay device adapted to be electrically connected to the AC power line in the protected premises for impressing a coded relay signal onto said AC power line in response to the receipt of said intrusion signal, a controller adapted to be electrically connected to said AC power line for impressing a coded controller signal onto said AC power line in response to the receipt of said coded relay signal, and a slave device adapted to be electrically connected between said AC power line and an alarm device for activating said alarm device in response to the receipt of said coded controller signal, and wherein said coded relay signal and said coded controller signal comprise predetermined carrier frequency signals that are digitally pulse code modulated with one complete cycle of the AC power line waveform being used to transmit each bit of information in said coded signals with a digital "1" corresponding to a carrier frequency pulse being generated during the positive (negative) half cycle of the AC power line waveform and a digital "0" corresponding to a carrier frequency pulse being generated during to the negative (positive) half cycle of the AC power line waveform;

the improvement comprising;

processor means in said signal relay device and processor means in said controller for determining if other coded signals are being transmitted over said AC power line both prior to and during the transmission of said coded relay and coded controller signals, respectively, and delaying or aborting said respective transmissions in the event other intelligence on said AC power line is detected.

32. The security system according to claim 31 wherein said processor means in said signal relay device and said controller are adapted to look for the presence of said predetermined carrier frequency on said AC power line both prior to transmission of said respective coded signals and during the unused half cycle of the AC power line waveform during the transmission of said respective coded signals.

33. The security system according to claim 32 wherein said processor means in said signal relay device and said controller are further adapted to wait a random period of time following a determination that other intelligence is present on said AC power line before again attempting transmission of said respective coded signals.

34. The security system according th claim 33 wherein said processor means in said signal relay device and in said controller are further adapted to determine if noise levels in excess of a predetermined amount are present on said AC power line both prior to and during transmission of said respective coded signals and delay or abort said respective transmissions in the event excessive noise levels on the AC power line are detected.

35. The security system according to claim 34 wherein said processor means in said signal relay device and in said controller are further adapted to wait said random period of time following the detection of excessive noise levels on said AC power line before again attempting transmission of said respective coded signals.

36. The security system according to claim 35 wherein said processor means in said signal relay device and said controller are adapted to look for the presence of excessive noise levels on the AC power line both prior to transmission of said respective coded signals and during the unused half cycle of the AC power line waveform during the transmission of said respective coded signals.