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Monday, 23 October 2006


Tim Stoffel

I will agree with the author that there are digital reception challenges out there. They are different than analog, and create their own set of problems.

For TV, the coding that was selected was optimized for the typical RF environment found in much of this country-- long-distance reception in wide-open markets. Granted, less of the population lives in these areas, but they have fewer distribution choices than do people in the cities. The 8VSB modulation system is at it's best in 'fixed' links typical of the ordinary TV household-- mobile was never really a big issue because few people watch TV while in motion. Those that argue for mobile 8VSB reception have more interest in non-TV business models than they do TV business models.

Radio, on the other hand, is used mobile much of the time. There, I puzzle why there is this push for digital when the analog signal works OK most of the time, and works even when the signal is less than perfect. Digital does offer opportunity for new and expanded use of the medium, but with truly annoying problems like 'cliff effect'. If the digital system is considerably more fragile than the old analog system, it will be slow to adopt, or may never adopt. The move towards higher and higher frequencies is not helping, either. Satellite and IP radio rely on microwave signals, which behave in very different ways (to the user) than do the low frequencies where traditional radio is used. It is definitely trickier to receive a radio signal broadcast at microwave than one broadcast at lower frequencies. To be truly successful, a system using microwave 'broadcasting' has to be extremely roboust, which limits the number of bits available for the service it is supposed to provide. Thus, there is a diminishing return on investment for some of these new radio technologies.

The thing that may very well save over-the-air TV is the skyrocketing costs of cable and DBS. If rates keep increasing, it will (as it already has) drive people back to over-the-air. Radio is a different story. Radio has to be above all, reliable. The radio can't act like a computer, losing signal then having to reaacquire it. It has to act like we have always expected it to act. Anything less, and people will be reluctant to adopt it.

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