Posted by: Stephen Wildstrom on February 5, 2009
Spreading FUD—fear, uncertainty, and doubt—is an old marketing technique in the tech business—and Washington policy debates. The discussion of the now-postponed digital TV transition has been mired in an unusual amount of FUD. You’d think that television might get a story that so intimately concerns itself right, but not if you read headlines like “ Rabbit ears get reprieve” used by CNN both on the air and on its Web site.
So here’s the nitty-gritty on what will happen to over-the-air TV signals when the DTV transition finally occurs. (If you get all your TV content from cable or satellite, you can stop here; you’ll probably never notice the transition.)
Currently, television stations broadcast on three bands, VHF-low (Channels 2-6), VHF-high (Channels 7-13), and UHF (Channels 14-69). Most UHF tuners go up to 83, but channels 70-83 were converted to cell phone use in the 1980s. Once analog broadcasting is shut down, channels 52-69 will also be repurposed, mostly for wireless data and public safety, and all of the digital stations will operate on channels 2-51.
How well an existing antenna, either set-top "rabbit ears" or a rooftop rig, will work for digital signals is going to vary a lot from situation to situation, and the results you get testing digital broadcasts today is not necessarily indicative of what will happen June 12, the new cutoff date. Some digital stations will continue operating as they do today, but some will move to new frequencies and some will be broadcasting from new tower locations; either change could affect your reception and may require, at a minimum, adjustment of your antenna. There is, by the way, no such thing as a digital antenna. Digital vs. analog makes a big difference to the circuitry in a TV set, but to an antenna, FM radio waves--that's what TV signals are--are just FM radio waves. Antennas are turned for the frequencies they receive, not the nature of the signals.
The other crucial difference is what a weak signal means for your viewing experience. Analog signals degrade gracefully. As the signal weakens, the picture gets snowy and the sound may get fuzzy, but it's up to the viewer to decide just when it becomes unwatchable. Digital TV is much more of a go-no go proposition. With a weak signal, the picture breaks down into big pixelated blocks before disappearing altogether. Even worse, the audio breaks up like a bad wireless phone connection. Most people quickly find the effects of even a moderately poor digital signal intolerable. That means that some people who got by with rabbit ears may have to go to an outside antenna and some people with rooftop antennas may have to upgrade them for higher gain.