Alternative Motion Sensing
Motion sensors can also work by sending a straight beam of light across a distance, such as a door frame or gateway. The receiver and transmitter communicate constantly that certain parameters are OK. When the beam is broken by movement, the transmitter reports a break and the receiver confirms. The motion sensor system then reports a signal to lights, a door, an audio chime or a security system.
Some motion sensors can function using sound and echolocation, the system of bouncing sound out and measuring how its echo reflects back. This is the same style of motion sensing that is used in nature by bats and dolphins to detect movements.
Motion Sensor Masking
Low technology motion sensors can be fooled by either slow disturbances or bending the reflection. Motion sensors are triggered by fast changes or "rapid changes" in the radio wave or light beam patterns. If motion is slow enough, it has been known to fool a motion sensor into overlooking movement. In terms of bending the reflection, if a properly curved lens can be put in place of the beam transmitter, it is possible to warp the expectation of the reflection. This could fool the receiver into seeing a different area of echo.
Tags: bending reflection
