ALARM SIGNALLING NETWORK

• US 3,735,396 A
• Filed: 08/10/1971
• Issued: 05/22/1973
• Est. Priority Date: 08/10/1971
• Status: Expired due to Term

• Current Assignee: Signatron, Inc.
• Original Assignee: Edward H. Getchell
• Inventors: Getchell, Edward H.
• Primary Examiner(s): Yusko, Donald J.
• Application Number:
  US05/170,558
• Time in Patent Office: 651 Days
• Field of Search: 340/408,409,213,413,163
• US Class Current: 340/505
• CPC Class Codes: G08B 26/005 with substations connected in series, e.g. cascade

Abstract

An alarm signalling network which monitors the alarm status of a plurality of separate zones under surveillance. A control station supplies a composite signal for transmission to a receptor station at each of the zones, which signal includes interrogation portions to which the receptor stations respond. Each receptor station thereupon produces an alarm status signal, which are included as alarm status signal portions of the composite signal. The composite signal is transmitted via a common transmission link between the control station and receptor stations, at least one of the receptor stations having means for displaying the alarm status from one or more of the other receptor stations, and the operations of the control and receptor stations are appropriately synchronized.

Claims

1. An alarm signalling network for monitoring the alarm status of a plurality of separate zones under surveillance, said network comprising a control station for producing a composite signal which includes interrogation signals for transmission to each of said zones;

a receptor station at each of said zones for receiving said composite signal, each said receptor station including means responsive to one of said interrogation signals for producing a signal signifying the alarm status of said zone for transmission in said composite signal;

common transmission link means interconnecting said control station and said receptor stations for transmitting said composite signal from said control station to each of said zone receptor stations;

at least one of said zone receptor stations further including means responsive to said interrogation and alarm status signals from one or more of the others of said zone receptor stations for displaying the alarm status thereof; and

means at said control station and at each of said receptor stations for synchronizing the operations of said control station and said zone receptor stations.

2. An alarm signalling network in accordance with claim 1 wherein each of said zone receptor stations includes means responsive to the alarm status signals from one or more of said other receptor stations for displaying the alarm status of said other receptor stations.

3. An alarm signalling network in accordance with claim 2 wherein each of said zone receptor stations includes means responsive to the alarm status signals from all of said other receptor stations for displaying the alarm status of all of said zones under surveillance.

4. An alarm signalling network in accordance with claim 1 wherein said control station and said receptor stations are connected in a series configuration in said network.

5. An alarm signalling network in accordance with claim 1 wherein said control station and said receptor stations are connected in a parallel configuration in said network.

6. An alarm signalling network in accordance with claim 1 wherein said control station is positioned at one of said zones under surveillance.

7. An alarm signalling network in accordance with claim 1 wherein said control station produces a composite signal comprising a plurality of successive frames, each said frame including a synchronization signal and an interrogation address signal identified with a selected zone receptor station, and a signal portion reserved for transmitting an alarm information signal;

and each said selected zone receptor station in response to its selected interrogation address signal furnishes an alarm status signal for transmission in said reserved signal portion of the frame of said composite signal containing its selected interrogation address signal for transmission by said common transmission link means.

8. An alarm signalling network in accordance with claim 7 wherein said control station includes means for producing a plurality of synchronization pulses and address enabling pulses;

means responsive to said address enable pulse for generating a sequence of pulses interrogation address signals each identified with a different receptor station; and

line driver means responsive to said synchronization pulse and to said pulsed interrogation address signals for feeding said signals to said common transmission lInk means to produce said composite signal.

9. An alarm signalling network in accordance with claim 8 wherein said interrogation address signal generating means includes counter means for sequentially producing a plurality of address signals each in the form of a parallel generated pulse group, each said pulse group identified with one of said receptor zones;

address signal means responsive to the sequential feeding of said parallel generated pulse groups for sequentially providing a plurality of said pulse interrogation address signals each in the form of a series generated pulse group; and

means for feeding said synchronization pulses and said pulsed interrogation address signals to said line driver means in a prescribed sequence for the formation of said composite signal.

10. An alarm signalling network in accordance with claim 9 wherein said line driver means comprises a two phase current source;

first means responsive to said synchronization pulses for driving one phase of said current source;

second means responsive to said pulse interrogation address signals for driving the other phase of said current source at a time different from the time at which said first means drives said one phase;

whereby said synchronization signals are fed to said common transmission link means when said one phase is driven and said pulsed interrogation address signals are fed to said common transmission link means when said other phase is driven.

11. An alarm signalling network in accordance with claim 1 wherein each said zone receptor station comprises zone interface means for receiving said composite signal at said zone receptor station and for transmitting said composite signal from said zone receptor;

means for sequentially storing said interrogation signals and said alarm status signals received in said composite signal;

means for decoding said alarm status signals and said interrogation signals and for feeding said alarm status signals to one or more selected display means for displaying the alarm status of one or more of the zone receptor stations in said network.

12. An alarm signalling network in accordance with claim 11 wherein each said zone receptor station further includes means for producing a signal representing the alarm status of said zone receptor station;

and means responsive thereto for supplying said alarm status signal to said zone interface means for providing an indication of said alarm status in said composite signal for transmission by said common transmission link means.

13. An alarm signalling network in accordance with claim 12 wherein each said zone receptor station further includes means for synchronizing the operation of said storing means, said decoding and feeding means, and said alarm status signal supplying means.

14. An alarm signalling network in accordance with claim 12 wherein each said zone receptor station further includes means for averaging the alarm status signals fed to said display means over a plurality of interrogation cycles and for displaying the alarm status indicated by said alarm signals only if said alarm status is repeatedly fed to said display means over said plurality of said cycles.

15. An alarm signalling network in accordance with claim 14, and further including means for manually discontinuing the display of the alarm status indicated by said alarm status signals.

16. An alarm signalling network in accordance with claim 12 wherein said control station produces said interrogation signals in said composite signal in the form of pulsed interrogation address signals and further produces synchronization pulse signals in said composite signal to provide for the synchronizing of the operation of said control station and said receptor stations.

17. An alarm signalling network in accordance with claim 16 and further wherein said zone interface means in each said zone receptor station includes circuit means responsive to said composite siGnal on said common transmission link means for detecting said synchronization pulse signals and to feed signals representing said synchronization pulse signals to said zone receptor station;

circuit means responsive to said composite signal on said common transmission link means for detecting the alarm status signals and the pulsed interrogation address signals present in said composite signals and to feed signals representing said alarm status and said address signals to said zone receptor station for storage; and

means for detecting the presence of said alarm status signal indicating the alarm status of said receptor station and for inserting said alarm status signal into said composite signal for transmission by said common transmission link means.

18. An alarm signalling network in accordance with claim 14 wherein each said averaging means is responsive to the alarm status signal received with reference to a selected zone and includes means for storing said alarm status signals over a selected number of interrogation cycles;

means for supplying a latch trip voltage when an alarm message is present for a preselected number of times within said selected number of interrogation cycles;

latching means responsive to said latch trip voltage for actuating an alarm display unit.

19. An alarm signalling network in accordance with claim 18 wherein said latch trip voltage supplying means includes a low pass filter responsive to the stored alarm status signals for producing a gradually increasing voltage when an alarm message is present for a preselected number of times during said selected number of interrogation cycles;

means for supplying a reference voltage;

voltage comparator means responsive to said reference voltage and to said gradually increasing voltage supplied from said low pass filter means for producing an output voltage when said voltages are equal.

20. An alarm signalling network in accordance with claim 17 wherein said voltage supplying means includes an up/down counter means responsive to the stored alarm status signals for producing an output voltage when the number of times an alarm status signal is received exceeds the number of times no alarm status signal is received by a preselected count.

21. An alarm signalling network in accordance with claim 7 wherein said control station includes means for supplying a substantially constant current on said common transmission link means during said reserved signal portions of each said frame.

22. An alarm signalling network in accordance with claim 21 wherein each said receptor station includes switch means for transmitting, or for interrupting the transmission of, said constant current on said transmission link means during the reserved portion of the frame associated with said receptor station;

whereby the alarm status of said receptor station is furnished to said common transmission link.

23. An alarm signalling network in accordance with claim 10 wherein said line driver means further includes means for stabilizing the current from said current source when said current source is driven in either said one phase or said other phase.

24. An alarm signalling network for monitoring the alarm status of a receptor station through a transmission link, said network comprising a control station for providing a composite signal comprising a plurality of successive frames, each said frame including at least a synchronization signal and a signal portion reserved for transmitting an alarm information signal, said control station including means for supplying a substantially constant current on said transmission link during said reserved signal portions of each said frame;

and said receptor station including switch means for transmitting, or for interrupting the transmission of, said constant current on said transmission in link in accordance with a predetermined code during the reserved signal portion of each said frame, whereby the alArm status of said receptor station is furnished to said transmission link.