Digital radio is coming to America, and when it arrives, it may signal the death of the medium as we know it.
For the first time in modern communications history, there's a distinct possibility that an entire form of media may make itself obsolete by the transformation from analog to digital. Broadcasters are wholeheartedly supporting the transition anyway.
That's because the value of a radio station isn't in what it plays over the air. The real value of any radio station is in the slice of spectrum it occupies.
From listening to the radio industry, you'd think Digital Audio Broadcasting (DAB) was the best thing since FM. Lofty promises have been made about vast improvements in sound quality over today's analog radio signals.
Digital radio will revolutionize the medium, all right. Just not in the way we're being led to believe.
Field tests of the DAB system and publicly-known details about how it works point more toward DAB as a ploy to expand a radio station's spectrum real estate - not about making radio itself any better.
The Standard Sets the Scene
As we tell this tale, here's a couple major points to remember: unlike most of the rest of the world - who've adopted a digital radio standard that calls for stations to move to a whole new band on the spectrum - America's broadcast industry lobbied for a technology called In-Band On-Channel (IBOC) DAB.
The U.S. television industry has also slowly been going digital over the last few years; as a result, all TV stations are moving to new "digital frequencies." But with IBOC, radio stations won't have to leave their familiar spots on the AM or FM dials.
An analog radio channel on the FM band in the U.S. is 200 KHz wide. This is why station dial positions end only in odd numbers (88.1, 90.3, 91.5, 94.7, 103.9, etc.). This was done initially to keep stations in the same geographical area from interfering with each other.
However, the IBOC-DAB system of calls for 430 KHz of bandwidth to be used for each digital radio signal - in effect, when radio stations go digital, they will double the space they take up on the dial.
Fattening radio signals in this manner brings up several concerns, of which the primary involves interference.
If all radio stations more than double their bandwidth, closely-spaced and smaller-power stations might get drowned out on the dial by higher-wattage neighbors.
Real-world tests of IBOC FM broadcasts in Virginia in 2000 produced harmful interference to other radio stations spaced near the digital guinea pig. Recordings of this interference are available online - they sound, basically, like a buzzsaw cutting through a nearby station's signal.
Better Sound? Listen Closely...
In addition to the interference concerns, the radio industry's lofty promises of improved audio quality are turning out to be more hype than truth.
In fact, a recent article in Current magazine (a publication for the public radio industry) contained this stunning admission: "(The) IBOC model flanks a station's analog signal with two low-level digital signals."
Translation: IBOC DAB isn't really a new way of broadcasting - it simply wraps two digital "sidebands" around a traditional analog signal. In fringe areas, or in instances where interference poses a problem, an IBOC radio station's signal will default to analog - the same old technology used today.
Which brings us to this question: why does digital radio require twice the bandwidth, if the signal you'll hear won't actually be any different?