Operation Tinsel

'Tinsel' was a British system for the transmission of highly amplified engine noise to saturate the German night-fighter speech control radio frequencies (1943/May 1945).

The system comprised an audio microphone mounted inside one of the bomber’s engine nacelles, with the output fed into the aeroplane’s standard radio transmitter/receiver unit. The wireless operator could listen in to the frequencies used by the defending forces and then, when he heard a German transmission, tune his transmitter into the Luftwaffe frequency and transmit the amplified engine noise on the same frequency, thus overwhelming the German transmission.

Although not very effective as the noise produced acted merely as background noise to the transmitted speech, 'Tinsel' did have the effect of making it more difficult for night fighter crews to pick out the instructions received from the ground controller.