MOTION DETECTOR FOR DETECTING TAMPERING AND METHOD FOR DETECTING TAMPERING

• US 20100283611A1
• Filed: 11/14/2007
• Published: 11/11/2010
• Est. Priority Date: 11/14/2007
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Smith, Richard A.
• Granted Patent: US 8,319,638 B2
• Time in Patent Office: Days
• US Class Current: 340/568.1
• CPC Class Codes: G08B 13/126 for a housing, e.g. a box, a safe, or a room
• CPC Class Codes: G08B 13/1436 with motion detection
• CPC Class Codes: G08B 13/193 using focusing means
• CPC Class Codes: G08B 15/001 Concealed systems, e.g. disguised alarm systems to make covert systems

Abstract

A motion detector and a method for detecting a tampering of the motion detector. The tampering can include a spraying or brushing of a lens of the motion detector. The motion detector comprises a lens, a single sensing section for detecting infrared signals within a protected area, and detecting vibrations on the lens in the form of acoustic signals, the vibrations and the infrared signal causing a voltage change in the single sensing section, a first and second amplifier for amplifying the voltage change for processing for tampering and motion, respectively, first and second filter for filtering the voltage change for processing for tampering and motion, respectively, a microcontroller for determining if the detected voltage change is consistent with a pattern that is indicative of tampering or motion and alarm generating section for generating a tamper alarm or a motion alarm based upon the determination by the microprocessor.

Claims

1. A method for detecting tampering of a motion sensor comprising the steps of:

detecting a voltage change in sensing element;

determining simultaneously if the detected voltage change is indicative of tampering or motion; and

generating an alarm signal based upon the determination.

2. The method for detecting a tampering of a motion sensor according to claim 1, wherein the determining step comprises the sub steps of:

amplifying the voltage change using a first preset gain;

filtering the voltage change by filtering out a portion of the voltage change outside a first bandwidth;

evaluating characteristics of the amplified and filtered voltage change for characteristics indicative of tampering.

3. The method for detecting a tampering of a motion sensor according to claim 1, wherein the determining step comprises the sub steps of:

amplifying the voltage change using a second preset gain;

filtering the voltage change by filtering out a portion of the voltage change outside second bandwidth;

evaluating characteristics of the amplified and filtered voltage change for characteristics indicative of motion.

4. The method for detecting a tampering of a motion sensor according to claim 1, wherein the generating step comprises the step of generating a first alarm signal if the voltage change has characteristics indicative of tampering, and a second alarm signal if the voltage change has characteristics indicative of motion.

5. The method for detecting a tampering of a motion sensor according to claim 4, wherein said first alarm signal is different from the second alarm signal.

6. The method for detecting a tampering of a motion sensor according to claim 5, further comprising the step of transmitting the first alarm signal and second alarm signal to a control panel.

7. The method for detecting a tampering of a motion sensor according to claim 5, further comprising the step of transmitting the first alarm signal and second alarm signal to a central monitoring station.

8. The method for detecting a tampering of a motion sensor according to claim 1, wherein said tampering is masking a lens by spraying a coating which blocks an infrared signal.

9. The method for detecting a tampering of a motion sensor according to claim 1, wherein said tampering is masking a lens by brushing a coating which blocks an infrared signal.

10. The method for detecting a tampering of a motion sensor according to claim 2, wherein said amplified and filtered voltage change is compared with a predetermined amplitude threshold and a predetermined duration threshold.

11. The method for detecting a tampering of a motion sensor according to claim 2, wherein the predetermined amplitude threshold includes a first amplitude threshold and a second amplitude threshold and the predetermined duration threshold includes a first duration threshold and a second duration threshold, the first amplitude and the duration threshold is used in the evaluation of the amplified and filtered voltage change with respect to a spraying, and the second amplitude and second duration threshold is used in the evaluation of the amplified and filtered voltage change with respect to a brushing.

12. A motion detector for detecting a tampering comprising:

a lens for focusing an infrared signal;

a single sensing section for detecting the focused infrared signals within a protected area and detecting vibrations on the lens in the form of acoustical and mechanical signals, the vibrations and the infrared signal cause a voltage change in the single sensing section;

a first amplifier for amplifying the voltage change for processing for tampering;

a second amplifier for amplifying the voltage change for processing for motion;

a first filter for filtering the voltage change for processing for tampering;

a second filter for filtering the voltage change for processing for motion;

a microcontroller for determining if the detected voltage change is consistent with a pattern that is indicative of tampering or motion; and

alarm generating section for generating a tamper alarm based upon the determination by the microcontroller.

13. The motion detector of claim 12, wherein said single sensing section comprising a pyro-electric sensor.

14. The motion detector of claim 12, wherein the processing for tampering and the processing for motion is in parallel.