It was just a matter of time before the digital age made its way to the rather unsophisticated car radio. When you come to think of it, not much has happened to car radios since 1965 or so when FM was introduced. FM was a great step in improving the sound quality output of a car radio and now has almost completely supplanted AM radio. Yes, we now have CD players and other playback systems, but the radio part of your car's audio system hasn't really changed... until now.

A new technology is almost ready to be introduced which will change the way we listen to the radio in our cars and in the home too. It's called CD radio, pay-radio, digital-satellite radio and Radio Fee America. It's been ten years in the making and it's supposed to be introduced in the U.S. market later this year.

There are two providers for satellite radio: XM Radio and Sirius Radio-which have exclusive distribution rights to the technology for the United States. Like in the early days of cellular phones, digital satellite radio requires a fairly large investment in infrastructure to make such a system viable on a nationwide basis.

Both systems rely on satellites (two for XM and three for Sirius) that will hover in geostationary orbit over the continent (Sirius has a high elevation elliptical orbit rather than the traditional geostationary.) In addition to the satellites which will broadcast the signals 'round the clock, both XM and Sirius will have ground-based terrestrial repeaters to repeat the signal once it's earthbound. The satellite radio signal can't pass through buildings and other natural obstructions in the way FM does.

Because the signal is digital, it will have no distortion and should be close to CD sound quality. However, the new system won't work with existing car radios and so will require an investment in either a new radio or perhaps some add-on that makes it possible for old radios to receive the signal. New carmakers should have the technology available on 2001 models. Most of the carmakers have signed on, as have most of the radio manufacturers.

Of course, the radio service is not free. There will be a monthly fee of $9.95, but in return you'll be able to receive about 100 channels of programming-and about half of these are claimed to be commercial-free. For example, there'll be a country channel, a vintage rock channel, a jazz channel and so forth-similar to the way some Internet radio providers operate. And there'll be all-news, all-sports and talk radio, too.

Industry observers are hailing this as the biggest breakthrough in radio since FM. It all depends, I think, on how many people are willing to shell out yet another monthly fee. The better sound quality is always a plus, but my feeling is that it will be more beneficial for home use rather than in a car environment where there is so much road noise to contend with. FM sounds pretty good in high-end car audio systems already. And although half of the programming will supposedly be commercial free, obviously the other half won't be.