The British were using radar more effectively
than the Germans realised for air defence, but the Luftwaffe had their own electronic means to increase their air attacks'
effectiveness. One system was called Knickebein ("crooked leg"), was used in which carefully positioned radio transmitters
were placed in friendly territory broadcast specially targeted navigational beams that intersected over specific bombing targets
in enemy territory. Bombers equipped with technology to detect these beams were guided towards a target and received a signal
to drop their bombs when they were (roughly) overhead. This allowed for somewhat more accurate bombing at night when British
air defence was at its weakest.
Although British intelligence had heard
rumours about this system they were not taken seriously until a British science advisor to MI6, Reginald
Victor Jones, gathered evidence of its existence and its threat. Jones convinced the high
command of the system and confirmed it with special examination flights. Jones was put in charge of developing solutions which
often involved interfering with the beams to make attacking aircraft go widely off course. Germans resorted to other navigational
systems, but Jones and the Telecommunications
Research Establishment (TRE) were able to neutralise each of those as well. The bombing effectivness
for the Germans decreased. But with the beams no longer accurate many civilian areas that would not normally have been targeted