Cochrane distortion
Cochrane distortion was the phase fluctuation in subspace fields. All warp drives generated such interference in the warp fields they generate. 

In 2366, Commander William T. Riker was able to access the warp field phase adjustment subsystem of the Ferengi starship Krayton. The subsystem was responsible for suppressing the subspace interference generated by the ship's warp engines. Riker was able to set up a simple oscillation in the system. The oscillation allowed stronger Cochrane distortions to occur in the warp field. The modified subspace interference static was then embedded to all the subspace communication signals, sent by the Krayton, as a subcarrier pattern. Wesley Crusher recognized the pattern of the Cochrane distortions as the Algolian ceremonial rhythm, the signal Riker had sent. ()

See also
Cochrane
Subspace oscillation
Warp
Physics