English: Pre-World War 2 photograph of Japanese Emperor Hirohito inspecting an array of acoustic aircraft locators. Their location is unknown. Prior to the development of radar in World War 2, military air defence forces used these devices to locate approaching enemy aircraft by listening for the sound of their engines. Each locator consists of two pairs of horn detectors, one pair on a horizontal axis and one pair on a vertical axis. The output of each pair is attached by rubber hoses to a stethoscope-type headphone worn by a technician. By using their stereophonic hearing and rotating the horn axis until the aircraft noise sounds "centered" in the earphones, the bearing and elevation of the aircraft can be determined.
Français : Photographie datant d'avant la Seconde Guerre mondiale montrant l'empereur japonais Hiro Hito inspectant une série de détecteurs aériens acoustiques. Le lieu est inconnu. Avant le développement des radars durant la Seconde Guerre mondiale, les forces de défense antiaériennes utilisaient ces appareils pour localiser les appareils ennemis via le bruit de leurs moteurs. Chaque détecteur est composé de deux paires de trompes, l'une sur l'axe horizontal et l'autre sur l'axe vertical. La sortie de chacune des paires est reliée par des tuyaux en caoutchouc à un écouteur en forme de stéthoscope porté par un technicien. En bougeant l'axe des trompes jusqu'à ce que le son soit centré dans les écouteurs, l'élévation et la direction de l'appareil pouvait être déterminée.
Date
before 1945
date QS:P,+1945-00-00T00:00:00Z/7,P1326,+1945-00-00T00:00:00Z/9
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2006-03-09 23:03 Ema Zee 400×300× (87610 bytes) pre World War II Japanese photograph of Emperor Hirohito inspecting an acoustic locator array. Acoustic locators were used prior to the invention of radar to locate aircraft. precise origin unknown.
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