page_title: Gee (navigation)
section_title: Technical details
hierarchical_section_title: Gee (navigation) / Technical details
caption_attribution_description: Crude diagram of time-difference principle. The delta between the time of receipt of synchronized signals from radio stations A and B is constant along each line of curve.
context_page_description: Gee, sometimes written GEE, was a radio navigation system used by the Royal Air Force during World War II. It measured the time delay between two radio signals to produce a fix, with accuracy on the order of a few hundred metres at ranges up to about 350 miles. It was the first hyperbolic navigation system to be used operationally, entering service with RAF Bomber Command in 1942.
  Gee was devised by Robert Dippy as a short-range blind landing system to improve safety during night operations. During development by the Telecommunications Research Establishment at Swanage, the range was found to be far better than expected. It then developed into a long-range, general navigation system. For large, fixed targets, such as the cities that were attacked at night, Gee offered enough accuracy to be used as an aiming reference without the need to use a bombsight or other external references. Jamming reduced its usefulness as a bombing aid, but it remained in use as a navigational aid in the UK area throughout and after the war.
caption: A single leg of a Gee chain lies along the "baseline" from stations A to B. At any point between these stations, a receiver will measure a difference in timing of the two pulses. This same delay will occur in many other locations along a hyperbolic curve. A navigational chart showing a sample of these curves produces a graph like this image.
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