Editing Gee (navigation) (section)

=== Upgrades ===
[[File:Mobile Gee station in Holland - CH 16520.jpg|thumb|Low-level photo of a light mobile Gee station operating in a field near Roermond, Holland. These forward stations provided Gee coverage deeper into Germany, as well as strong signals for aircraft returning to bases in Western Europe.]]

The first serious jamming was encountered on the night of 4/5 August 1942. This grew in strength as the bombers approached their target at Essen, and the signals became unusable at {{convert|10|to(-)|20|mi|km}} from the target. The newly formed southern chain was not yet known to the Germans and continued to be useful. On 3/4 December, a fix was made from this chain over [[Turin]] in Italy, at a range of {{Convert|730|mi|km|abbr=}}. This remained the operational record for Gee, bested only by a freak reception over [[Gibraltar]] at a range of {{Convert|1000|mi|km|abbr=}}.{{sfn|Campbell|2000|p=8}}

Counter-jamming efforts had already been considered, and resulted in the Gee Mk. II. This replaced the original receiver with a new model where the oscillators could be easily removed and swapped out to provide a range of operational frequencies. These included the original 20–30 MHz band, as well as new bands at 40–50, 50–70, and 70–90&nbsp;MHz. The navigator could replace these in flight, allowing reception from any active chain. Gee Mk. II went into operation in February 1943, at which point it had also been selected by the US [[8th Air Force]].{{sfn|Campbell|2000|p=9}}

On 23 April 1942, the go-ahead was given to develop mobile stations for Gee in preparation for the invasion of Europe. This would not only extend the range of the system eastward, but also allow stations to move and suddenly appear elsewhere if jamming became an issue. The first of an eventual three such mobile chains was formed up on 22 November 1943. This was put into operation on 1 May 1944 at [[Foggia]] in Italy, and was used operationally for the first time on 24 May. Other units were sent into France soon after [[D-Day]]. The mobile units in France and Germany were later replaced by fixed stations, the "heavies".{{sfn|Campbell|2000|pp=10–11}}

After the end of the war in Europe, Britain planned to send Lancasters to the Japanese theatre as part of [[Tiger Force (air)|Tiger Force]] and to use Gee for the passage of flights to Asia. Preparations began for Gee transmitters in [[Nablus]] (in Palestine) guiding the flights across the Middle East, but the [[surrender of Japan]] removed the need for this chain. This work was being carried out by MEDME, Cairo, under Air Vice-Marshal R. S. Aitken.

German bombers also used the Gee system for attacks on the UK; captured Gee receivers provided the electronics.{{sfn|Jones|1978|p=397}}