Thursday, 22 May 2014 18:49

Avoid Motion Detectors by Covering Yourself in Mud

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If you have seen the movie Predator, then you may remember the scene where Dutch (played by Arnold Schwarzenegger) avoids getting captured and killed by the Predator when he accidentally covers himself in mud, which hides the heat from his body. The Predator, using body heat signatures to identify its prey, can't detect Dutch even though looking right at him -- the mud hides his body's heat signature. Well, I haven't tested it (yet?), but the same concepts should apply when trying to avoid detection by a motion sensor light! (if you test this, let me know and I'll post the results!)

In previous articles I have discussed how motion sensor lights work, and how the heat from objects moving across the motion sensing field will trigger a motion sensing light. This article is not meant to give you ideas for sneaking past someone's motion sensor, but instead is to help you better understand how your lights work and possibly help you better place your motion lights to pick up the type of motion you want to trigger your lights. I will plan to set up some testing in my backyard (using my kids - they will love it!) to see how well we can avoid our motion sensing lights--I'll post any results. Here are some suggestions and ideas on avoiding motion sensors (note that these apply to heat-sensing motion detectors like those typically found in motion lights - these do not necessarily apply to sound, beam or other detectors):

  • Avoid the detector range.  This one is the easiest, and the one you should make sure to think about when setting your motion lights.  Place the detectors in positions that don't easily allow them to be avoided.  Once you have set your detectors, test them by walking in areas around your lights to confirm they trigger when they should.
  • Adjust body temperature to mimic the temperature of the area covered by the motion detector.  The sensor picks up changes to light frequencies that result from changes to temperature of an object passing through the sensor range.  If the object moving through the sensor range has the same temperature as the area around it, then there is less chance that the sensor will trigger the light.
  • Mask / Hide the temperature of the object moving through the detector field.  As mentioned above, based on the detector picking up changes in temperature (and the resulting changes to the frequency of light), if the object is able to hide or mask its temperature, it may avoid detection.  An example of this would be the Predator movie example above.  Using a piece of glass to hide behind may also work to 'trick' the sensor, by reflecting the light back to the sensor, causing the sensor to 'think' that the light is simply being reflected back to it from a wall or other non-moving object.  The changed frequency caused by the heat from the moving object behind the glass will not reach the sensor, and the light will not be triggered.
  • Move extremely slowly through the sensor detection range.  By moving slowly and gradually, and pausing for extended periods of time, the sensor may not detect enough sudden change in temperature and frequency to trigger the light.
  • Be as quiet as possible.  Even for sensors that don't rely on audible triggers, certain types of sound may affect the light frequencies reaching the sensor, causing the sensor to trigger the light.

Keep in mind that there aren't any guaranteed ways to walk past a motion detector on a motion light and avoid activation of the light, based on the variables involved.  It is not true that different colors cause more or less likelihood that a sensor will activate.

Keep in mind that these tips apply to both outdoor motion lights and indoor motion lights.  Also, with motion sensor flood lights, you will generally get more ability to adjust the position of the sensor, compared to outdoor decorative motion lights.  Hopefully, this information will help you when you are deciding where to place your motion sensor lights to get the best sensing coverage for your home.


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