DTV channels will move, even if we don’t
August 7th, 2007Your local station should now know which channel to call home after the transition to digital TV is completed. The FCC announced final DTV channel assignments for more than 1,800 stations yesterday.
After analog TV broadcasts terminate on February 17, 2009, many stations will assume new channel numbers. No worries, though (well, almost; I’ll explain later). Surprisingly, viewers won’t generally need to learn new channel lineups, because stations will retain their customary on-air identities. Channel 11 will still promote itself as channel 11, for instance, even if it has moved to channel 32.
The familiar channel numbers from the analog era can be preserved to a large extent, thanks to “channel virtualization.”
Along with their programming, local television stations send channel information over the air to be received by digital TV sets and DTV converter boxes. If you watch digital TV using an antenna, your television receiver should keep track of the actual “RF” (for radio frequency) and virtual channel numbers. When you set up your new digital TV, or a digital-to-analog converter box attached to your old TV, the digital tuner will scan for available stations. For each station, a virtual channel number corresponding to its traditional analog channel number should be displayed. That feature allows viewers to navigate to the channels they have always known.
One new wrinkle for viewers is that digital TV allows each local station to offer several channels of separate programming. That technology is known as multicasting. If good old channel 11 offers three digital channels, they could be numbered 11.1, 11.2 and 11.3 on your antenna-equipped digital TV or converter box.
The preservation of existing channel numbers in virtual form is intended to minimize viewer confusion during the DTV transition. Station owners, hoping to hold onto their audiences throughout the switch, will be pleased if viewers know where to find them.
Despite the convenience of virtualization, over-the-air DTV viewers will sometimes need to know the station’s actual RF channel number. If you already watch digital TV broadcasts today, you may want to know which DTV channels will be moving after the analog shutdown. After the moves take place, you may need to rescan the channels on your digital TV or DTV converter box. You may also find it necessary to reposition your antenna. Some stations will be moving from VHF (channels 2 through 13) to UHF (channels 14 through 51, post-transition), or vice versa. Given these changes, a different antenna will be needed in some cases.
If you subscribe to cable or satellite TV, after the transition I would expect local channel lineups to match up with stations’ traditional analog over-the-air channel numbers in many, but not all, cases. Some cable or satellite systems place some local stations on strange channel numbers today, and the switch to digital TV won’t entirely eliminate that problem. Also, if the cable or satellite operator chooses to carry additional multicast channels, they may be plopped onto unusual channel numbers. Finally, the FCC still must decide what will happen to local channels for analog cable TV customers. The outcome of that decision could affect cable channel numbering.
Final channel assignments for 13 DTV stations are still pending at the FCC.
• Links: FCC: press release [pdf], fun for lawyers [pdf, 134 pages]