System and method for high-sensitivity sensor

• US 7,623,028 B2
• Filed: 07/28/2006
• Issued: 11/24/2009
• Est. Priority Date: 05/27/2004
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Lawrence Kates
• Inventors: Kates, Lawrence
• Primary Examiner(s): Crosland, Donnie L
• Application Number:
  US11/494,988
• Publication Number:
  US 20060267756A1
• Time in Patent Office: 1,215 Days
• Field of Search: 340/521
• US Class Current: 340/521
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 2110/50 Air quality properties
• CPC Class Codes: F24F 7/007 with forced flow using ducting systems F24F7/06
• CPC Class Codes: G01N 33/0006 Calibrating gas analysers
• CPC Class Codes: G01N 33/0065 using more than one threshold
• CPC Class Codes: G01N 33/0075 for multiple spatially distributed sensors, e.g. for environmental monitoring transmission systems for measured values G08C
• CPC Class Codes: G08B 1/08 using electric transmission ; transformation of alarm signals to electrical signals from a different medium, e.g. transmission of an electric alarm signal upon detection of an audible alarm signal
• CPC Class Codes: G08B 17/10 Actuation by presence of smoke or gases , e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
• CPC Class Codes: G08B 17/107 for detecting light-scattering due to smoke
• CPC Class Codes: G08B 17/11 using an ionisation chamber for detecting smoke or gas
• CPC Class Codes: G08B 19/00 Alarms responsive to two or more different undesired or abnormal conditions, e.g. burglary and fire, abnormal temperature and abnormal rate of flow
• CPC Class Codes: G08B 21/182 Level alarms, e.g. alarms responsive to variables exceeding a threshold
• CPC Class Codes: G08B 25/007 Details of data content structure of message packets; data protocols
• CPC Class Codes: G08B 25/009 Signalling of the alarm condition to a substation whose identity is signalled to a central station, e.g. relaying alarm signals in order to extend communication range
• CPC Class Codes: G08B 25/10 using wireless transmission systems G08B25/009 takes precedence
• CPC Class Codes: G08B 27/005 with transmission via computer network
• CPC Class Codes: G08B 29/26 by updating and storing reference thresholds
• CPC Class Codes: H04B 1/401 for selecting or indicating operating mode
• CPC Class Codes: H04B 1/69 Spread spectrum techniques

Abstract

A sensor unit includes at least one sensor configured to measure an ambient condition. The controller can be configured to receive instructions, to report a notice level when the controller determines that data measured by the at least one sensor fails a report threshold test corresponding to a report threshold value. The controller can also be configured to obtain a plurality of calibration measurements from the at least one sensor during a calibration period and to adjust the threshold based on the calibration measurements. The controller can be configured to compute a first threshold level corresponding to background noise and a second threshold level corresponding to sensor noise, and to compute the report threshold value from the second threshold. In one embodiment, the sensor unit adjusts one or more of the thresholds based on ambient temperature.

Claims

1. A sensor unit, comprising:

at least one sensor configured to measure an ambient condition; and

a controller, said controller configured to receive instructions, said controller further configured to report a notice level when said controller determines that data measured by said at least one sensor fails a report threshold test corresponding to a report threshold value, said controller configured to obtain a plurality of calibration measurements from said at least one sensor during a calibration period and to adjust said threshold based on said calibration measurements, said sensor unit further configured to adjust said threshold based on ambient temperature, said controller configured to compute a first threshold level corresponding to background noise and a second threshold level corresponding to sensor noise, said controller configured to compute said report threshold value from said second threshold.

2. The sensor unit of claim 1, wherein said at least one sensor comprises a smoke sensor.

3. The sensor unit of claim 1, said controller configured to receive said report threshold value from a central control system.

4. The sensor unit of claim 1, said controller configured to receive said report threshold value from an external source.

5. The sensor unit of claim 1, wherein said at least one sensor comprises a water-temperature sensor.

6. The sensor unit of claim 1, wherein said at least one sensor comprises a moisture sensor.

7. The sensor unit of claim 1, wherein said at least one sensor comprises a humidity sensor.

8. The sensor unit of claim 1, wherein said at least one sensor comprises a carbon monoxide sensor.

9. The sensor unit of claim 1, wherein said at least one sensor comprises a flammable gas sensor.

10. The sensor unit of claim 1, wherein said at least one sensor comprises a door-open sensor.

11. The sensor unit of claim 1, wherein said at least one sensor comprises a broken-window sensor.

12. The sensor unit of claim 1, wherein said at least one sensor comprises an intrusion sensor.

13. The sensor unit of claim 1, wherein said at least one sensor comprises a power-failure sensor.

14. The sensor unit of claim 1, wherein said report threshold value is computed, at least in part, as an average of a plurality of sensor data values.

15. The sensor unit of claim 1, wherein said report threshold value is computed, at least in part, as a weighted average of a plurality of sensor data values.

16. The sensor unit of claim 1, wherein said alert level is computed according to how far a sensor reading has risen above said report threshold value.

17. The sensor unit of claim 1, wherein said alert level is computed as a function of how far and how rapidly sensor readings have risen above said threshold value.

18. The sensor unit of claim 1, wherein said alert level is computed as a function of how many sensor readings have been measured above said threshold value.

19. The sensor unit of claim 1, wherein said alert level is computed as a function of what percentage of recent sensor readings have been measured above said threshold value.

20. The sensor unit of claim 1, wherein a threshold value of an optical smoke sensor is computed using, at least in part, temperature information from a temperature sensor.

21. The sensor unit of claim 1, said sensor unit further comprising a fan configured to improve air exchange between a sensor chamber and ambient air.

22. The sensor unit of claim 21, wherein said fan is provided to said controller, said controller configured to operate said fan during one or more measurement periods.

23. The sensor unit of claim 21, wherein said fan is provided to said controller, said controller configured to operate said fan prior to one or more measurement periods.

24. The sensor unit of claim 21, wherein said controller reports a diagnostic error at least when said second threshold does not exceed said first threshold.

25. The sensor unit of claim 21, wherein said controller reports a diagnostic error at least when said second threshold does not exceed said first threshold.

26. The sensor unit of claim 21, wherein said controller measures said first threshold and said second threshold in response to a command.

27. The sensor unit of claim 21, wherein said controller measures said first threshold and said second threshold at power-up.