Alarm sensor multiplexing

• US 5,900,806 A
• Filed: 05/01/1998
• Issued: 05/04/1999
• Est. Priority Date: 05/22/1992
• Status: Expired due to Term

• Current Assignee: Directed, LLC (VOXX International Corporation)
• Original Assignee: DEI Holdings Incorporated
• Inventors: Birchfield, Jerry W., Issa, Darrell E.
• Primary Examiner(s): Wu, Daniel J.
• Application Number:
  US09/073,048
• Time in Patent Office: 368 Days
• Field of Search: 340/426, 340/428, 340/429, 340/430, 340/511, 340/517, 340/518, 340/521, 340/825.06, 340/825.57, 340/825.63, 340/870.13, 340/870.19, 307/10.2-10.6, 180/287
• US Class Current: 340/426.25
• CPC Class Codes: B60R 2025/1013 Alarm systems characterised by the type of warning signal, e.g. visual, audible
• CPC Class Codes: B60R 25/1003 Alarm systems characterised by arm or disarm features
• CPC Class Codes: B60R 25/1004 Alarm systems characterised by the type of sensor, e.g. current sensing means using door lock sensors B60R25/1001
• CPC Class Codes: B60R 25/1018 Alarm systems characterised by features related to the general power supply
• CPC Class Codes: B60R 25/104 characterised by the type of theft warning signal, e.g. visual or audible signals with special characteristics
• CPC Class Codes: G01P 13/00 Indicating or recording presence, absence, or direction, of movement electric switches H01H; counting moving objects G06M7/00
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• CPC Class Codes: G07C 2009/00238 the transmittted data signal containing a code which is changed
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2009/00849 programming by learning
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: G07C 9/21 having a variable access code
• CPC Class Codes: G07C 9/28 the pass enabling tracking or indicating presence
• CPC Class Codes: G08B 13/1436 with motion detection
• CPC Class Codes: G08B 25/008 Alarm setting and unsetting, i.e. arming or disarming of the security system
• CPC Class Codes: G08B 25/018 Sensor coding by detecting magnitude of an electrical parameter, e.g. resistance
• CPC Class Codes: G08B 25/10 using wireless transmission systems G08B25/009 takes precedence
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence
• CPC Class Codes: G08B 29/24 Self-calibration, e.g. compensating for environmental drift or ageing of components
• CPC Class Codes: G08B 29/26 by updating and storing reference thresholds
• CPC Class Codes: G08C 17/02 : using a radio link
• CPC Class Codes: G08C 19/22 : by varying the duration of individual pulses
• CPC Class Codes: G08C 19/28 : using pulse code
• CPC Class Codes: G08C 2201/51 : Remote controlling of devices based on replies, status thereof
• CPC Class Codes: G08C 2201/62 : Rolling code
• CPC Class Codes: H04J 13/0074 : Code shifting or hopping

Abstract

A security system for monitoring a protected area and sounding an alarm including a plurality of sensors arranged about a protected area for sensing incoming threat, device for generating at least one pulse for each sensor activated by the incoming threat to the area, an alarm controller for receipt of the pulses and sounding of an alert, and a single wire connecting outputs of the sensors to the controller for transmitting the pulses generated by the plurality of sensors to the controller.

Claims

1. A system for monitoring an area and sounding an alarm comprising:

a) at least one sensor arranged about a protected area;

b) at least one pulse generator for generating at least one pulse for said sensor activated by incoming threat to said area;

c) a controller for receipt of said pulses and sounding of an alert;

d) a single wire connecting output of said pulse generator to said controller for transmission of said pulses to said controller;

e) said pulse generator generating a first pulse in response to a first level of threat and a second pulse in response to a second level of threat, each said pulse having a different assigned pulsewidth, wherein only said first pulse is generated for communication of said first level of threat received by said sensor, and said second pulse is generated for communication of said second level of threat received by said sensor.

2. The device of claim 1 further including a counter for identifying said sensor generating said pulse by the pulsewidth assigned to each said sensor and its first and second pulses.

3. A system for monitoring an area and sounding an alarm comprising:

a) at least one sensor arranged about a protected area for sensing incoming threat to said protected area and for generating at least one electrical signal responsive to said incoming threat;

b) a pulse generator producing a single pulse in response to a first level of threat and a second pulse in response to a second level of threat, each said pulse having a different assigned pulsewidth for each said sensor;

d) a single wire connecting output of said pulse generator and said controller for transmission of said pulses to said controller.

4. The device of claim 3 further including a counter for measuring said pulsewidth of each said pulse.

5. The device of claim 4 wherein said counter is integral to said controller.

6. A method of multiplexing the output of at least one sensor over a single wire comprising the steps of:

a) arranging at least one sensor about a protected area;

b) said sensor sensing incoming threat to said protected area and generating at least one electrical signal responsive to said incoming threat;

c) converting said electrical signal to a first pulse in response to a first level of threat and a second pulse in response to a second level of threat, each said pulse having a different assigned pulsewidth for each said sensor; and

d) transmitting said pulses from at least one sensor to said controller via a single wire connecting said sensors and said controller for receipt of said pulses and sounding of an alert;

e) measuring said pulsewidth of each said pulse with a counter and identifying said sensor and said level of threat by its pulsewidth.

7. The method of claim 6 further including the step of rejecting transient signals indicated by a pulse having a pulsewidth less than a minimum specified time parameter.

8. The method of claim 6 further including the step of rejecting signals caused by a failed component indicated by a pulse having a pulsewidth greater than a maximum specified time parameter.