File:Acoustic aircraft detection horns.jpeg
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Acoustic_aircraft_detection_horns.jpeg (700 × 490 pixels, file size: 67 KB, MIME type: image/jpeg)
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Summary[edit]
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English: 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. |
| Date | |
| Source | Downloaded 2012-06-10 from Douglas Self (2012) Acoustic Location and Sound Mirrors, The Museum of Retro Technology, Douglas Self website |
| Author | Unknown author |
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This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
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This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 15:47, 10 June 2012 | | 700 × 490 (67 KB) | Chetvorno (talk | contribs) |
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