Transwarp signature

A transwarp signature is a detectable energy phenomenon created as a byproduct of the use of the transwarp conduits utilized by the Borg.

In 2373, when it became apparent that they were approaching Borg space, Harry Kim, operations officer on the USS Voyager, configured the ship's long-range sensors to scan for transwarp signatures, so as to provide an early warning system for the approach of Borg vessels. 

In 2376, Captain Janeway and a team from Voyager utilized the Delta Flyer to track the transwarp signature of a Borg sphere which had abducted Seven of Nine. Utilizing a stolen transwarp coil, they entered a transwarp conduit and adjusted their course to follow it, eventually arriving at the Borg Unicomplex.

From within transwarp space it was easy to detect the residual and active transwarp signatures of other ships that had generated conduits. It was also possible to match signatures to specific ships. Debris within a conduit registers on sensors as multiple signatures.