A covariant isolator was a piece of technology on Template:ShipClass vessels, used to clear up garbled subspace messages.
In 2371, while trying to contact Telek R'Mor through the Harry Kim wormhole, Lieutenant B'Elanna Torres was concerned that the covariant isolator would not be able to penetrate the unusual phase variance in the wormhole to hear his message. However, the crew of the USS Voyager was able to establish contact with R'Mor by narrowing the filter band pass. (VOY: "Eye of the Needle")