subchannel

plural subchannels

1. broadcastingA distinct division of a channel or frequency band.
2. broadcastingAn additional frequency owned by a television broadcaster used for less lucrative content.

   […] TV shows you watched when you were younger, you'll likely find them on the subchannels of your local TV stations — which are available free to anyone with a TV set and a good antenna.

   2020, Michael R. Miller, My TV for Seniors

   1 more example

   It may well be that our viewers are going to say, "You know what? We don't care as much about 10801. We would rather have you rerun 'CBS News' on a subchannel and show your prime time entertainment in a lesser definition of digital television" […]

   2001, United States. Congress. House. Committee on Energy and Commerce. Subcommittee on Telecommunications and the Internet, Digital Television: A Private Sector Perspective on the Transition: Hearing..., page 98

3. computingA distinct part of an I/O channel associated with a specific device.