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DTV brings more channels, but beware 'cliff effect'

17.12.2008
Old-school broadcast television just got a new lease on life with the transition to digital television (DTV) signals.

In February 2009, full-power television stations are mandated to . There's good and bad news for those viewers who don't have cable or satellite TV. The good news: If you are currently watching analog television programming via over-the-air signals, you may start to receive additional channels after attaching a digital converter box to your existing TV or upgrading to an HDTV.

The bad news: Depending on where you live and the type of antenna you are using, certain DTV channels may experience "freezing" or be unavailable, because the signal is too weak.

We just made the switch, replacing a 2002-era Sansui 25" tube set with a 46" Samsung high-defintion LCD TV. We are one of the few homes in our neighborhood that doesn't have cable television, but we live close enough to Boston to receive all of the local network affiliates plus an assortment of analog UHF channels with varying degrees of clarity. We didn't need an HDMI cable, or any other special DTV gear -- the old rabbit ears for our Sansui plugged right into the back of the new Samsung HDTV.

I was shocked at the transformation. Besides the larger screen and the HD signals for some of the network stations, almost all of the UHF digital signals came in crystal clear, even though we had to partially collapse the antenna to fit behind the Samsung. We also gained a new set of digital channels which had previously been unavailable. Before, we had received nine analog channels, but now we get 16 DTV channels.

Where did the extra stations come from? A few channels had split into two signals. For instance, WHDH/channel 7, the Boston NBC affiliate, became 7-1 (WHDH-HD) and 7-2 (WHDH-SD), which showed a national weather map, the seven-day outlook, and clips from WHDH meteorologists. The 7-2 channel broadcasts in SD, which stands for standard definition -- the same resolution as the old analog system if shown in a 4:3 aspect ratio. WGBH/Channel 2, the main VHF public television station in Boston, is now an HD channel (2-1) and a wide-screen SD channel (2-2) playing the same programming.