The digital TV cliffhanger

[Commentary] In preparing for America's big switch to digital-only broadcast next year, the US government has neglected to say much about trees. And hills. And buildings. These can disrupt digital signals and result in blank screens. It's a significant oversight that may cost millions of viewers money and aggravation. Even new digital TVs may have reception problems. The reason is the "cliff effect." When analog signals are disturbed, the picture gradually degrades. But digital signals are much more sensitive to disturbance, and screens can suddenly break into pixels or freeze, or just be blank. There's no way to fix this, except to re-aim an antenna, upgrade to a more expensive and stronger one - probably on the roof - or subscribe to cable or satellite.