Editing Direction finding (section)

===Huff-duff===
[[File:HMS Belfast - Huff Duff.jpg|thumb|upright|right|FH4 "Huff-duff" equipment on the museum ship {{HMS|Belfast|C35|6}}]]

A major improvement in the RDF technique was introduced by [[Robert Watson-Watt]] as part of his experiments to locate [[lightning]] strikes as a method to indicate the direction of thunderstorms for sailors and airmen. He had long worked with conventional RDF systems, but these were difficult to use with the fleeting signals from the lightning. He had early on suggested the use of an [[oscilloscope]] to display these near instantly, but was unable to find one while working at the [[Met Office]]. When the office was moved, his new location at a radio research station provided him with both an [[Adcock antenna]] and a suitable oscilloscope, and he presented his new system in 1926.

In spite of the system being presented publicly, and its measurements widely reported in the UK, its impact on the art of RDF seems to be strangely subdued. Development was limited until the mid-1930s, when the various British forces began widespread development and deployment of these "[[high-frequency direction finding]]", or "huff-duff" systems. To avoid RDF, the Germans had developed a method of broadcasting short messages under 30 seconds, less than the 60 seconds that a trained Bellini-Tosi operator would need to determine the direction. However, this was useless against huff-duff systems, which located the signal with reasonable accuracy in seconds. The Germans did not become aware of this problem until the middle of the war, and did not take any serious steps to address it until 1944. By that time huff-duff had helped in about one-quarter of all successful attacks on the U-boat fleet.