Before the radar was invented there were some great ideas floating around…
Turning sound receptor - used as an "advanced" their own ears. Inventor Professor Meyer in 1880.
English locator 1938
Acoustic radar, kept the United States armed forces in 1921
Acoustic marine locator. Jean Auscher from France.
Experiments of Englishman Reva Bacon in 1898
English Locator MK1 (1914-1918 biennium). Used in the First World War to detect enemy aircraft.
Four-"ears" locator. Date and manufacturer unknown.
Acoustic radar, kept the United States armed forces in 1921
Czech locator, 1920 (?). Two ears are vertical, two horizontal
Czech locator that can be used by one person.
English locator, 1930's
Japanese locator from the 1930's
French locator from the 30's
German locator RRH, 1940
Mobile Locator U.S. Army (early 40's)
England, 1928 10 meters concrete antenna
England, in 1930 70 meters Locator-wall. Can "hear" aircraft flying at a distance of 100 km