A Downside to Digital TV

For a simple device, the antenna has generated a lot of misinformation. Over-the-air digital signals behave differently from analog signals. That won’t matter to most Americans come the switchover to digital TV broadcasting. They either own a digital TV or get their signal through cable or satellite. But 17 million households have an analog TV that receives its signals over the air — 13 million of them use a rabbit-ear antenna. That means that not only do they have to buy a digital converter box; they may have to buy a new antenna. An additional 18 million homes have TVs that get over-the-air signals, but the residents have other TVs that are connected to cable or satellite services. Estimates from a computer simulation run by Centris found that more than nine million households that now get programming over the air could lose one or more stations they now receive. Although digital broadcasts will provide a superior picture and more channels than old analog broadcasts, digital reception is more easily blocked by hills, trees and buildings than analog reception. Furthermore, analog degrades gradually, with the picture displaying snow or ghosts (image echoes) as the signal becomes weaker. But the digital signal stays uniformly crisp until the signal gets weak; then the picture suddenly drops out, a phenomenon that engineers call the “cliff effect.”
http://www.nytimes.com/2008/04/24/technology/personaltech/24basics.html?...
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