Electronic Counter Measures
Electronic Countermeasures (ECM) involved deceiving radar and communications, thus making them less useful. The Electronic Warfare Unit therefore researched ways to hinder enemy radar.
ECM could be active, meaning that the user was attempting to interfere with enemy radar with the hopes of making it less useful. It could also be passive which was more of a reconnaissance mission into how the radars worked so that they could use ECM in the future.
There were two main ways of accomplishing active ECM. The first was “jamming” which involved using foil dropped from planes to interfere with radar data. This made it difficult to figure out where the actual aircraft was located. The British called this Window, the Americans Chaffe, and the Germans Duppel.
This took quite a bit of effort though. For example, to make it seem like there was one B29 aircraft, about 5000 pieces were needed.
The other method of ECM was using signals to confuse enemy radar or communications. While on the same frequency, a signal could be used to mask the information being received by the enemy.