PROGRAMMED TIME DIVISION MULTIPLEXED CODED TONE TRANSMISSION SYSTEM

• US 3,803,594 A
• Filed: 07/17/1972
• Issued: 04/09/1974
• Est. Priority Date: 07/17/1972
• Status: Expired due to Term

• Current Assignee: Johnson Controls International BV (Johnson Controls International plc)
• Original Assignee: Carl F. Klein, Lawrence B. Korta, Michael B. Mclean
• Inventors: Korta, Lawrence B., McLean, Michael B., Klein, Carl F.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US05/272,575
• Time in Patent Office: 631 Days
• Field of Search: 340/413R,49R
• US Class Current: 340/518
• CPC Class Codes: G08B 25/00 Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
• CPC Class Codes: G08B 25/04 using a single signalling line, e.g. in a closed loop

Abstract

An alarm transmission system for transmitting alarm information provided by a plurality of alarm sources to a central monitor over a common transmission line includes zone monitoring circuits having a code generator for generating a monitor code comprised of a continuous sequence of bits for transmission over the transmission line to the central monitor, alarm multiplexing circuits including alarm storage circuits which provide separate storage locations for storing alarm outputs provided by each alarm source and a sequencing circuit controlled by the alarm data storage circuits in response to the receipt of an alarm output provided by an alarm sensor to generate a plurality of control signals in a predetermined time sequence, including a control signal for enabling an inhibit circuit to inhibit the transmission of the monitor code to the central monitor and a further control signal for enabling an alarm source identification code generator to effect readout of the alarm storage circuits to generate an alarm source identification code comprised of a sequence of coded bits, each bit of which represents the condition of a different alarm sensor, for transmission over the transmission line to the central monitor to enable identification of the source of the alarm.

Claims

1. In a security system including a transmission line for carrying alarm information from a plurality of protected areas within a predetermined zone to a central monitor that is remote from the protected areas, zone monitoring means including code generating means for continuously generating a line monitor code comprised of a known sequence of coded bits, means for enabling said monitor code to be transmitted over said transmission line to said central monitor, alarm multiplexing means including alarm storage means having separate storage locations for each protected area for storing a first data bit whenever the corresponding protected area is secure and a second data bit to indicate an alarm condition for the corresponding protected area, sequencing means controlled by said alarm data storage means in response to the storage of a second data bit therein to inhibit the transmission of said monitor code to said central monitor and means controlled by said sequencing means to effect the generation of an alarm source identification code comprised of a plurality of bits in a sequence coded to represent the conditions of all of the protected areas for transmission over said transmission line to said central monitor.

2. In a security system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including an intrusion detector for each protected area, normally enabled to be operable in a secure mode to provide an alarm output in response to an intrusion of the corresponding protected area, alarm source monitoring means including means responsive to an alarm output provided by at least one of said intrusion detectors to generate an alarm code for transmission over said transmission line to said central monitor, said alarm code comprising an alarm indication followed by a plurality of bits in a sequence coded to represent the conditions of all of the intrusion detectors to thereby indicate the source of the alarm, access-secure means including an individual access switch means for at least certain ones of said intrusion detectors for individually disabling an associated intrusion detector to cause said intrusion detector to be operable in an access mode to thereby permit an intrusion of a corresponding protected area without providing an alarm output, said access-secure means including condition indicating means for continuously providing a plurality of output signals over a plurality of outputs thereof, each of said output signals indicating the mode of operation of a different one of said intrusion detectors, and access-secure monitoring means for scanning said output of said access-secure means to generate an access-secure code for transmission over said transmission line to said central monitor, said access-secure code being comprised of a plurality of signals coded to represent the mode of operation of each of said intrusion detectors.

3. In a security system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including an individual alarm sensor for each protected area, each of said alarm sensors being normally operable in a secure mode to provide an alarm output signal in response to an intrusion of an associated area, alarm source monitoring means including code generating means for continuously generating a line monitor code comprised of a known sequence of code bits which is normally transmitted over said transmission line to said central monitor to indicate that all protected areas are secure, alarm multiplexing means including alarm storage means having an individual storage means for each alarm sensor for receiving the alarm output signals provided by an associated alarm sensor, and alarm data readout means including sequencing means enabled by said alarm storage means whenever an alarm output signal is provided by one of said alarm sensors to generate a plurality of control signals in a predetermined time sequence, means responsive to a first control signal to inhibit the transmission of the monitor code to said central monitor, means responsive to a second control signal to thereafter effect readout of the alarm storage means to generate an alarm code comprised of a plurality of bits which represent the conditions of the alarm sensors for transmission over said transmission line to said central monitor to enable the identification of the source of the alarm.

4. A system as set forth in claim 3 wherein said alarm source monitoring means includes access switch means for individually disabling said alarm sensors, whereby said alarm sensors are operable in an access mode to permit an intrusion of a corresponding protected area without providing an alarm output, said access switch means including condition indicating means for continuously providing a plurality of output signals over a plurality of outputs thereof, each of said output signals indicating the mode of operation of a different one of said alarm sensors and access-secure monitoring means including scanner means for periodically scanning said outputs to generate an access-secure code for transmission over said transmission line to said central monitor, said access-secure code being comprised of a plurality of bits in a sequence coded to represent the mode of operation of each of said alarm sensors.

5. A system as set forth in claim 4 wherein said alarm source monitoring means includes clock pulse generating means for providing pulses for controlling said code generating means to generate the bits of the monitor code at a predetermined rate, and clock pulse dividing means for extending pulses from said clock pulse generating means to said scanner means for enabling said scanner means to generate said access-secure code at a rate slower than said predetermined rate.

6. A system as set forth in claim 4 wherein said scanner means includes an output gate circuit having a plurality of inputs and an output, and a plurality of scan gate circuits, each of said scan gate circuits having a first input individually connected to one of the outputs of said condition indicating means and an output individually connected to one of the inputs of said output gate circuit, and enabling means for extending an enabling signal to a second input of each of said scan gate circuits in a preselected sequence to gate the output signals provided by said condition indicating means to said output gate circuit to thereby provide said access-secure code at the output of said output gate circuit.

7. A system as set forth in claim 6 wherein said scanner means includes output point sequence code generator means for controlling said enabling means to thereby preselect the sequence in which said scan gates are enabled.

8. In a security system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including an alarm sensor for each protected area, each of said alarm sensors being operable to provide an alarm output signal to indicate an alarm condition for an associated protected area, code generating means for continuously generating a line monitor code comprised of a known sequence of coded signals which are normally transmitted over said transmission line to said central monitor, alarm multiplexing means including sequencing means enabled in response to the receipt of an alarm output signal proVided by an alarm sensor to provide a plurality of control signals in a predetermined time sequence, inhibit means responsive to a first control signal provided by said sequencing means to inhibit the passage of said monitor code sequence to said transmission line, and alarm source identification means responsive to a second control signal provided by said sequencing means to provide an alarm source identification code comprised of a plurality of bits in a sequence coded to represent the conditions of said protected areas for transmission over said transmission line to said central monitor.

9. A system as set forth in claim 8 wherein said alarm multiplexing means includes alarm storage means having separate alarm output storage means for each of said alarm sensors for storing the alarm output signals provided by the alarm sensors.

10. A system as set forth in claim 9 wherein each of said alarm sensors are further operable to provide a supervisory alarm output signal in response to a component failure of the alarm sensors, and wherein said alarm storage means further includes separate supervisory storage means for each of said alarm sensors for storing supervisory alarm outputs provided by the alarm sensors, said sequencing means being responsive to either an alarm output signal or a supervisory output signal to provide said control signals for effecting the transmission of alarm information to said central monitor.

11. A system as set forth in claim 10 wherein each of said alarm output storage means comprises a first normally reset bistable data storage circuit and each of said supervisory storage means comprises a second normally reset bistable data storage circuit, a first data storage circuit being set whenever an alarm output signal is provided by an associated alarm sensor and a second data storage circuit being set whenever a supervisory alarm output signal is provided by an associated alarm sensor.

12. A system as set forth in claim 8 wherein said alarm multiplexing means includes alarm storage means including a separate alarm flip flop for each alarm sensor, each alarm flip flop being normally reset to provide an output bit at a first logic level and being set in response to an alarm output signal provided by an associated alarm sensor to provide an output bit at a second logic level.

13. A system as set forth in claim 12 wherein said alarm source identification means comprises parallel-to-serial converter means including a plurality of gate circuits, each of said gate circuits being individually connected to the output of a different one of said alarm flip flops, output gating means having a plurality of inputs individually connected to an output of a different gate circuit, and enabling means responsive to said second control signal to sequentially enable said gate circuits to pass the bits stored in the alarm flip flops of said alarm storage means to said output gating means to thereby provide a sequence of bits at an output of said gating means representing the alarm data stored in all of said alarm flip flops.

14. A system as set forth in claim 13 wherein said alarm source identification means further includes point sequence code generator means for controlling said enabling means to enable preselection of the sequence in which said gate circuits are enabled and thus the sequence in which the bits stored in the alarm flip flops are passed to said output gating means.

15. A system as set forth in claim 13 which includes line monitoring means at said central monitor having reference code generating means for generating a reference code comprised of a sequence of coded bits, each bit of which is normally identical with corresponding bits of the monitor code at any given time, code comparator means for receiving the bits of the monitor code and comparing the monitor code bit sequence with the reference code bit sequence, alarm indicating means controlled by said code comparator means for providing an alarm indication whenever correspondinG bits of the sequences are different and decoder means responsive to the bits of an alarm source identification code to determine the source of the alarm.

16. A system as set forth in claim 15 wherein said alarm data readout means further includes means responsive to a control signal provided by said alarm source identification means as enabled, to provide a sync signal, prior to the readout of the alarm flip flops of said alarm storage means, for transmission over said transmission line to said central monitor to enable said decoder means to be responsive to the bits of the alarm source identification code to identify the source of the alarm.

17. A system as set forth in claim 13 wherein said sequencing means includes means enabled by said enabling means of said alarm source identification means after the bits stored in all of the alarm flip flops have been gated to said output gating means to provide a reset signal for resetting all of the alarm flip flops.

18. A system as set forth in claim 17 wherein said sequencing means includes means enabled by said reset signal to provide a signal for disabling said inhibit means to thereby reinitiate the transmission of said monitor code to said central monitor.

19. In a security system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including an individual alarm sensor for each protected area, each of said alarm sensors being normally operable in a secure mode to provide an alarm output in response to an intrusion of a corresponding protected area, code generating means for continuously generating a line monitor code comprised of a continuous sequence of logic level bits, tone generating means responsive to the bits of the monitor code to generate tone signals of first and second frequencies in a sequence coded to represent the bits of the minitor code for transmission over said transmission line to said central monitor, alarm multiplexing means including alarm storage means for storing the alarm outputs provided by the alarm sensors, and readout means including sequencing means controlled by said alarm data storage means in response to the receipt of an alarm output signal provided by an alarm sensor to provide a control signal for inhibiting the passage of said monitor code bit sequence to said tone generating means, and alarm source identification means responsive to a further control signal provided by said sequencing means to effect readout of the alarm data source means to provide an alarm source identification code comprised of a sequence of logic level bits, each bit of which represents the condition of a different protected area, for controlling said tone generating means to generate a further tone sequence comprised of tone signals of said first and second frequencies coded to represent the conditions of the protected areas for transmission over said transmission line to said central monitor, access-secure means for rendering each of said alarm sensors individually operable in an access mode to enable intrusions of a corresponding protected area without providing an alarm output, and access-secure monitoring means operable to periodically scan said access-secure means to generate an access-secure code for transmission over said transmission line to said central monitor, said access-secure code being comprised of a sequence of bits, each bit of which indicates the mode of operation of a different one of the alarm sensors.

20. A system as set forth in claim 19 wherein said access-secure means comprises a plurality of access-secure switch means including an access-secure switch means individually associated with each alarm sensor for selecting the mode of operation of a corresponding alarm sensor, each of said access-secure switch means being operable to provide an output at a first logic level signal whenever the corresponding alarm sensor is operating in the access mode and an ouTput at a second logic level signal whenever the corresponding alarm sensor is operating in the secure mode, said access-secure monitoring means including scanner means for providing a sequential scan of all of said access-secure switch means to provide a sequence of bits comprised of the logic level signals being provided by access-secure switch means.

21. A system as set forth in claim 20 wherein said access-secure monitoring means includes further tone generator means responsive to each output at said first logic level to provide a tone signal of said third frequency and responsive to each output bit at the second logic level to provide a tone signal at said fourth frequency.

22. A system as set forth in claim 21 including line monitoring means at said central monitor including tone detecting means for receiving the access-secure tone sequence and providing a sequence of logic level bits coded to represent the access-secure code, and access-secure decoding means responsive to the bits of the access-secure code to provide an indication of the access-secure mode of operation for each of said alarm sensors.

23. A system as set forth in claim 22 wherein said scanner means includes means for enabling said further tone generator means to provide a scan initiate signal of one of the frequencies of said further pair, for transmission over said transmission line to said central monitor to enable said access-secure decoding means to be responsive to the bits of the access-secure code.

24. A system as set forth in claim 22 wherein said access-secure decoding means includes a plurality of indicator means, including first and second indicator means for each alarm sensor, said first indicator means being operable when enabled to indicate the corresponding alarm sensor is operating in the access mode and said second indicator means being operable when enabled to indicate the corresponding alarm sensor is operating in the secure mode, control means including a plurality of control circuits each individually associated with a different pair of indicator means for selectively enabling the associated indicator means, and gating means for gating each bit of the access-secure code to a different control circuit to effect enabling of one of the indicator means associated with each control circuit.

25. In a security system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including an individual alarm sensor being operable to provide an alarm output signal in response to an unauthorized intrusion of an associated area, alarm source monitoring means including code continuously generating means for generating a line monitor code comprised of a continuous sequence of logic level bits, tone generating means, bit gating means normally enabled to gate the bits of the monitor code to said tone generating means to effect the generation of tone signals of first and second frequencies in a sequence coded to represent the monitor code for transmission over said transmission line to said central monitor, alarm multiplexing means including alarm storage means for storing the alarm outputs provided by the alarm sensors, and readout means including sequencing means controlled by said alarm data storage means in response to the receipt of an alarm output signal provided by an alarm sensor to provide a control signal for disabling said bit gating means to thereby inhibit the passage of said monitor code bit sequence to said tone generating means, and alarm source identification means responsive to a further control signal provided by said sequencing means to effect readout of the alarm data storage means to provide an alarm source identification code comprised of a sequence of logic level bits, each bit of which represents the condition of a different protected area for controlling said tone generating means to provide a further tone sequence comprised of tone signals of said first and second frequencies in a sequence coded to represent the conditions of said protected areas for transmission over said transmission line to said central monitor.

26. A system as set forth in claim 25 wherein said alarm data readout circuits include tone generator disable means, including means responsive to said first control signal to provide a disabling signal for said tone generator means to inhibit the generation of tone signals for a predetermined time.

27. A system as set forth in claim 25 wherein said alarm source identification means includes means for providing a bit at a first logic level to represent an alarm condition for a protected area in which a corresponding alarm sensor is providing an alarm output signal and a bit at a second logic level to represent a secure condition for a protected area, and output means for extending the bits of the alarm source identification code to the tone generator means to effect the generation of a tone signal at said first frequency for each bit of alarm source identification code at said first logic level and a tone signal of said second frequency for each bit of the alarm source identification code at said second logic level.

28. A system as set forth in claim 25 including line monitoring means at said central monitor having tone detecting means responsive to the tone sequences provided by said alarm source monitoring means to provide sequences of logic level bits at an output thereof, reference code generating means for generating a reference code comprised of a coded sequence of logic level bits, each bit of which is normally identical with corresponding bits of the monitor code at any given time, code comparator means for receiving the bit sequence provided by said tone detecting means and comparing the monitor code bit sequence with the reference code bit sequence, alarm indicating means controlled by said code comparator means for providing an alarm indication whenever corresponding bits of the sequences are different, and alarm source identification decoder means responsive to the bits of the alarm source identification bit sequence to determine the source of the alarm.

29. A system as set forth in claim 28 wherein said alarm data readout means further includes means responsive to a signal provided by said alarm source identification means prior to the readout of said alarm data storage means, to generate a sync pulse of a predetermined duration for enabling said tone generator means to generate a sync tone of one of said frequencies for transmission over said transmission line to said central monitor, said alarm source identification decoder means including decoder means and decoder enable means responsive to said sync tone to enable said decoder means to be responsive to the bits of the alarm source identification code.

30. A system as set forth in claim 29 wherein said tone detecting means is responsive to said sync tone to provide a logic level sync pulse, and wherein said decoder enable means includes gating means and bistable switching means, said bistable switching means being set responsive to the inhibiting of the transmission of said monitor code to enable said gating means to pass the sync pulse provided by said tone detecting means to said decoder means.

31. In a security system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including an individual alarm sensor for each protected area, each of said alarm sensors being operable to provide an alarm output signal in response to an unauthorized intrusion of an associated area, code continuously generating means for generating a line monitor code comprised of a known sequence of coded bits, bit gating means for normally passing the bits of the monitor code to the transmission line for transmission to said central monitor, alarm multiplexing means including alarm data storage means for storing alarm outPut signals provided by the alarm sensors, and readout means including alarm source identification means operable when enabled to effect sequential readout of the alarm data storage means to provide an alarm source identification code comprised of a plurality of bits in a sequence coded to represent the conditions of all of the alarm sensors, and sequencing means including first means responsive to an alarm output signal provided by at least one of said alarm sensors to provide a first control signal for disabling said bit gating means to thereby inhibit the transmission of said monitor code to said central monitor, second means for providing a second control signal for enabling said alarm source identification means to generate said alarm source identification code for transmission to said central monitor, and line monitoring means at said central monitor including reference code generating means for generating a reference code comprised of a sequence of coded bits, each bit of which is normally identical with corresponding bits of the monitor code at any given time, input means for receiving the monitor code, code comparator means controlled by said input means for comparing the bits of the monitor code with the bits of the reference code, alarm indicator means controlled by said code comparator means for providing an alarm indication whenever the compared bits are different, and alarm source identification decoder means including gating means for receiving the alarm source identification code and alarm source indicating means controlled by said gating means to indicate the source of the alarm.

32. A system as set forth in claim 31 wherein said alarm data storage means includes a plurality of alarm storage flip flops including a separate alarm storage flip flop for each alarm sensor, each alarm storage flip flop being normally reset to provide an output at first logic level, and each alarm storage flip flop being set responsive to an alarm output signal provided by an associated alarm sensor to provide an output at a second logic level.

33. A system as set forth in claim 32 wherein said alarm multiplexing means includes output gating means having a plurality of inputs, each input being individually connected to an output of a different one of said alarm storage flip flops, and an output connected to an input of said sequencing means, said output gating means including an alarm gate, enabled by an output at said second logic level provided by one of said alarm storage flip flops to enable said first means of said sequencing means to provide said first control signal.

34. A system as set forth in claim 33 wherein said alarm data readout circuits include a control flip flop normally providing an output for enabling said bit gating means, said control flip flop being responsive to said first control signal to provide a further output for disabling said bit gating means.

35. A system as set forth in claim 32 wherein said alarm source identification means includes output gating means and a plurality of gate circuits, each of said gate circuits having an input individually connected to an output of one of said alarm storage flip flops and an output individually connected to an input of said output gating means, and enabling means, responsive to said further control signal to enable said gate circuits in a preselected sequence to extend the logic level outputs of said alarm storage flip flops to said output gating means, whereby said output gating means provides a sequence of logic level outputs representing the conditions of all of said alarm sensors.

36. A system as set forth in claim 35 wherein said alarm multiplexing circuits includes sync pulse generating circuit means enabled by said enabling means prior to the enabling of said gate circuits to provide a sync signal for transmission to said central monitor to enable the alarm source identification decoder means to be responsive to the bits of the alarm source identification code.

37. A system as set forth iN claim 36 wherein said alarm source indicating means comprises a plurality of indicator circuits including an indicator circuit corresponding to each alarm sensor, said gating means of said alarm source identification decoder means including a plurality of decoder gate circuits, each having inputs commonly connected to an output of said input means and an output individually connected to one of said indicator circuits, and further enabling means responsive to said sync pulse to enable said decoder gate circuits in a preselected sequence in synchronism with the enabling of the gating circuits of said alarm source identification means whereby each of the bits of the alarm source identification code is gated over said decoder gating means to a different indicating circuit.

38. A system as set forth in claim 37 wherein said alarm source identification means includes point sequence code generator means for controlling said enabling means to preselect the sequence in which said gating circuits are enabled, and wherein said alarm source identification decoder means includes further point code generator means, which is identical to said first point sequence code generator means for controlling the further enabling means of said alarm identification decoder means to preselect the sequence in which the decoder gate circuits are enabled.

39. In an alarm transmission system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including individual intrusion detector means for each protected area, each intrusion detector means being operable to provide an alarm output in response to the detection of movement of an intruder within the corresponding protected area, alarm source monitoring means including means for continuously generating a line monitor code comprised of a selected sequence of tone signals of predetermined frequencies for transmission over said transmission line to said central monitor and alarm multiplexing means including means responsive to each alarm output for inhibiting the transmission of said monitor code to said central monitor and means for generating an alarm source identification code which indicates the conditions of all of the protected areas for transmission over said transmission line to said central monitor, and line monitoring means at said central monitor including means enabled whenever the transmission of said monitor code is inhibited to provide an alarm indication at said central monitor and means responsive to the alarm source identification code to indicate the source of the alarm, and test signal generating means operable to provide a test signal for transmission over said transmission line to said alarm source monitoring means, said alarm source monitoring means further including test signal detecting means responsive to each test signal provided by said test signal generating means to enable at least one of said intrusion detector means to provide an alarm output.

40. An alarm transmission system as set forth in claim 39 wherein at least said one intrusion detector means comprises microwave motion detection means having means operable to produce Doppler alarm signals of frequencies within a predetermined range whenever a human intruder is moving within the corresponding protected area, alarm signal detecting means responsive to each of said Doppler alarm signals to provide an alarm output, and motion simulator means enabled a test signal provided by said test signal detecting means to generate signals of a frequency within said predetermined range to enable said motion detection means to provide an alarm output.

41. In a security system including a transmission line for carrying alarm information from a plurality of protected areas to a central monitor that is remote from the protected areas, alarm source means including an alarm sensor for each protected area, each of said alarm sensors being operable to provide aN alarm output signal to indicate an alarm condition for a corresponding protected area, alarm source monitoring means including means for continuously generating a line monitor code comprised of a selected sequence of coded signals for transmission over said transmission line to said central monitor, and alarm multiplexing means including means responsive to an alarm output signal for inhibiting the transmission of said monitor code and for generating an alarm source identification code indicating the conditions of all of the protected areas for transmission to said central monitor.

42. A system as set forth in claim 41 wherein at least certain ones of said alarm sensors include an intrusion detector normally operable in a secure mode to provide an alarm output in response to an intrusion of a corresponding protected area and operable in an access mode to permit intrusion of the protected area without providing an alarm output, and authorized entry switch means at the location of said intrusion detectors for enabling selection of the mode of operation of said intrusion detectors.

43. A system as set forth in claim 42 including access-secure monitoring means for periodically scanning said authorized entry switch means and providing an access-secure code for transmission to said central monitor for indicating the mode of operation of each of said intrusion detectors.