Digital subchannel

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Digital television in the United States supports multiple digital subchannels if the 19.4 Megabits-per-second (Mbit/s) bitstream is divided. Full quality 1080i HDTV requires 18 Mbit/s; however, many stations compress this down to 11 Mbit/s. A 720p HDTV signal can be compressed to 8 Mbit/s, and a SD signal compressed to 6 Mbit/s without perceivable loss of quality. 4 Mbit/s or less yields acceptable results if the subject in the video moves very little (such as a slideshow automated weather channel).

Therefore, station managers could run any of the following scenarios:

Scenario	Picture Format
Scenario A	1 slightly compressed 1080i HDTV
Scenario B	1 Compressed 1080i HDTV + 1 x Compressed 720p HDTV Subchannel
Scenario C	1 Compressed 1080i HDTV + 1 x Compressed SD Subchannel + Optional Slideshow type subchannel (such as NBC Weather Plus)
Scenario D	3 Compressed SD Channels
Scenario E	4 Highly Compressed SD Channels
Scenario F	5 Super Highly Compressed SD Channels

Many PBS stations around the country broadcast 4 SD channels during the daytime, and 1 HD + 1 SD channel at night. PBS offers the following channels: PBS DT (analog station), PBS HD (PBS-XP), PBS Kids & Family (PBS Kids Channel), PBS Select (Create), & PBS Learner (The Annenberg Channel).

Another more common use for digital subchannels is for CBS affiliates to show all of the early round games of the NCAA Basketball Tournament on their digital channel, which is subdivided into four different subchannels.

With the launches of The CW and MyNetworkTV, many television stations have been launching subchannels affiliating with The CW or MyNetworkTV. Other stations have launched separate independent stations on their DT-2 signals, such as WOWT and WDJT (which carries its broadcast Class A station WMLW as a digital signal).