Editing Gee (navigation) (section)

=== Gee-H ===
{{main|Gee-H (navigation)}}

Later in the war, Bomber Command wanted to deploy a new navigation system not for location fixing, but to mark a single spot in the air. This location would be used to drop bombs or target indicators for strikes by other bombers. The [[Oboe (navigation)|Oboe]] system provided this already; Oboe sent an interrogation signal from stations in the UK, "reflected" them from [[transceiver]]s on the aircraft, and timed the difference between the two signals using equipment similar to Gee. However, Oboe had the major limitation that it could only guide a single aircraft at a time and took about 10 minutes to guide a single aircraft to its target. A system able to guide more aircraft at once would be a dramatic improvement.

The result was a new version of the same basic Oboe concept, but reversed so that it was driven by the aircraft and reflected from ground-based transceivers. This would require equipment on the aircraft that could receive and measure the time difference between two signals. The reuse of the existing Gee equipment for this purpose was obvious. The new '''Gee-H''' system only required a single modification, the addition of a new transmitter that would send signals out for reflection from ground-based transceivers. With this transmitter turned off, the system reverted to being a normal Gee unit. This allowed it to be used in Gee-H mode during attacks, and then Gee mode for navigation back to their home airfields.