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| Audio SWR Analyzer |
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General
This device was developed for audio laboratories (and for university physics laboratories)
and allows the user to demonstrate the acoustical properties of various materials. By placing
a test material inside the SWR resonance tube and measuring the standing wave minima and maxima,
the absorption properties of the test material can be determined.
Technical
The Audio SWR analyzer is comprised of two components: the electronics module and the resonance
tube. The electronics module contains a very high fidelity sine wave generator which drives a
speaker via a low distortion amplifier. The speaker sets up a standing wave inside the resonance
tube where a movable microphone inside the tube can locate the minima and maxima. The test sample
is placed at the end of the tube and, depending on its acoustical properties, changes the minima,
maxima, and phase when compared to a perfectly solid (reflective) test sample. The signal from
the microphone is processed prior to being displayed on an analog meter. A microcontroller controls
all frequency setting, frequency counting, and 5 digit LED display updates.
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