Narrow-bandwidth television

Screenshot of a NBTV testcard on a 32-line system

Narrow-bandwidth television (NBTV) is a type of television designed to fit into a channel narrower than the standard bandwidth used for official television standards.

The three predominant worldwide broadcast television standards use either 6 MHz wide channels (as in the Americas and Japan, as ATSC and ISDB-T both use those standards) or 8 MHz (as in most of Europe with DVB-T). Narrow-bandwidth television refers to any method that reduces the bandwidth below that threshold. (These techniques are frequently used in traditional television to allow for multiple digital subchannels on the same bandwidth, but this is not true narrow-bandwidth as the standards do not allow for it, and the extra bandwidth in these cases is usually transferred to another channel.)