Ultrasonic Rangefinders send a small,
powerful burst of sound enrgy out, then time the return of the echo.
The echo time is directly related to the distance the sound wave
traveled in going out, bouncing off some object, then returning. The
name for using sound to measue distance is "sonar". This is how some
bats find their way and find their prey while flying at night. Polaroid
owns this sensor technology and licences it to companies such as EDP,
the manufacurer of this device. In the demo, the brightness of the lamp
is related to the distance sensed by the sonar.
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