Digital subchannel

Encyclopedia : D : DI : DIG : Digital subchannel

Digital television in the United States supports multiple digital subchannels if you divide the 19.4 Megabits-per-second (Mbit/s) bitstream. 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 A: 1 x less compressed 1080i HDTV

Scenario B: 1 x Compressed 1080i HDTV + 1 x Compressed 720p HDTV Subchannel

Scenario C: 1 x Compressed 1080i HDTV + 1 x Compressed SD Subchannel + (Optional Slideshow type subchannel)

Scenario D: 3 x Compressed SD Channels

Scenario E: 4 x Highly Compressed SD Channels

Many PBS stations around the country broadcast 4 SD channels during the daytime, and 1 HD + 1 DT channel at night. PBS offers the following channels: PBS DT, PBS HD, PBS Kids & Family, PBS Select, & PBS Learner.

In Minneapolis (DMA 15) PBS Broadcasts 5 SD Channels and on a separate channel has an HD Channel. PBS-HD, TPT2, MN Channel, TPT Kids, TPT Create, TPT Wx.

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