Acoustic aircraft detection horns

Autor:

Neznámý

Shortlink:

https://czwiki.cz/b/b6845

Zdroj:

Wikimedia Commons

Formát:

700 x 490 Pixel (68286 Bytes)

Popis:

Photo of an acoustic aircraft detection apparatus at Bolling Field, (now Joint Base Anacostia-Bolling), Washington D. C., USA, in 1921. Before radar was developed in WW2, acoustic horns like this were used by air defense forces to detect the sound of approaching enemy aircraft at a distance. The system shown here, apparently being tested, consisted of two conical horns attached by rubber tubes to a stethoscope earpiece in the observer's ears. The stereo receptor allowed the observer to determine direction of the aircraft. The building in the background is the Army War College at Fort McNair.

Licence:

Public domain

Credit:

Downloaded 2012-06-10 from Douglas Self (2012) Acoustic Location and Sound Mirrors, The Museum of Retro Technology, Douglas Self website

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