Fast Forward: Requiem for Analog TV


[This edition of Fast Forward was originally published in our February 2009 issue]

No doubt you’ve heard that analog TV in the U.S. goes off the air on February 17, replaced by digital TV. If you haven’t heard, you must be in a coma. Four times as much money has been spent to prepare Americans for this transition as the U.S. government spends on adult education each year. Who says politicians can’t get their priorities straight?

I’m dreading the switch. I’m a diehard who still plays vinyl records, subscribes to a daily newspaper, and snatches free TV from the ether with rabbit ears. And I’m not alone. Thirteen percent of U.S. households still depend on TV antennas.

Although the DTV transition won’t affect people who have cable or satellite TV, it does reveal an inherent flaw of digital technology. This flaw afflicts almost all digital media, including the digital photos you take, the digital video you record, and the digital music you download. Digital data can be rendered useless by minor damage that wouldn’t matter if the media were in analog form.

At my home, for example, DTV is a bust. NBC is the only network my indoor antenna can receive. CBS, ABC, and PBS are dead air. Yet my antenna points toward the region’s largest hilltop broadcast tower, just 10 miles away. For years I’ve received analog TV that’s a little snowy but quite watchable.

The problem is that DTV signals are typical of digital media. They are all or nothing. If anything interferes with the compressed bitstream of ones and zeroes, the error-correction algorithms may not be able to reconstruct the lost data. So, when a digital TV gets a weak signal, it doesn’t get a snowy picture—it gets no picture. The same errors can make digital photos, videos, and music unreadable. I’ve seen JPEG files irretrievably scrambled by a single data error.

By comparison, analog media are more robust. I’ve scanned 100-year-old photographic negatives that were scratched all to hell, but they still yielded usable images. I have restored 60-year-old acetate recordings that sounded like popcorn but were still audible.

To protect your digital media, keep multiple backups. Although this solution doesn’t apply to DTV, it will help preserve your digitally stored memories.

Tom Halfhill was formerly a senior editor for Byte magazine and is now an analyst for Microprocessor Report .

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