PURPOSE: To illustrate how RADAR and SONAR work.
DESCRIPTION: A low-frequency square wave input to a speaker emits a short pulse at the leading edge of the square wave, seen on the lower trace. The microphone picks up this pulse, displaying it on the upper trace; the initial pulse is the direct sound, while the second pulse is the reflection of the receding pulse off the screen. Moving the screen varies the time the reflected pulse returns to the microphone, producing acoustic radar.
REFERENCES: (PIRA unavailable.)
EQUIPMENT: Dual trace oscilloscope, square wave oscillator, supertweeter loudspeaker, microphone with microphone amplifier, optical rail with mounts as photographed.
SETUP TIME: 10 min.
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