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motion detector |
Also found in: Wikipedia | 0.01 sec. |
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motion detector A device to detect intrusion within an area to be protected. The device radiates waves (electromagnetic or ultrasonic, at a fixed frequency) that are reflected back to the device. If an intruder moves within the protected space, a change in frequency results which is detected and which activates an alarm. Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
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