Sonar
From Tardis Wiki, the free Doctor Who reference
Sonar was a detection system based on sound waves.
HMS Seaspite was converted into a sonar testing centre. (TV: The Sea Devils)
A signal transmitted by the Game Station masked the Dalek Fleet from sonar, radar and scanners. After he was taken to the Game Station in 200100, the Ninth Doctor cancelled this signal, revealing who was manipulating mankind. (TV: Bad Wolf)
