| 摘要 |
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.
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