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This is in fact how airplanes were detected before radar was invented. Not a joke. https://rarehistoricalphotos.com/aircraft-detection-radar-1917-1940/ https:

by paulmd 7y ago

This is in fact how airplanes were detected before radar was invented. Not a joke. https://rarehistoricalphotos.com/aircraft-detection-radar-1917-1940/ https://rarehistoricalphotos.com/aircraft-detection-radar-19... https://en.wikipedia.org/wiki/Acoustic_location https://en.wikipedia.org/wiki/Acoustic_location

DonHopkins 7y ago
Now you've made me want to dress up as an Airplane Detector for Halloween!