Most often these refer to the microwave links used to transmit the video and audio from the chopper back to the station. Especially with links used for choppers, these are two way links (a large link into the station and a much smaller one back). The backfeed provides two functions, first to provide audio and queues to the remote location and second, to allow the chopper to keep the link's antenna lined up with the station automatically.
It appears WTIC's switch to Marcus Communication's LTR system didn't work out?
For a while their conventional 455.250 (67.0) was rarely used while they were doing
a lot of testing on Marcus's. Now they seem to back using it full time...