Digital Audio Broadcasting Plays to Global Audience

THE world has just taken a big step toward a new kind of radio - perhaps the biggest step since the 1930 invention of FM.

It is called digital audio broadcasting (DAB). The technology promises to deliver music over the airwaves that sounds as good as a compact disc. Ironically, the nation farthest along in developing the technology - the United States - may have cut itself out of a potentially huge and lucrative broadcasting market.

The great leap forward came last week when the World Administrative Radio Conference (WARC) recommended that nations allocate the portion of the broadcasting spectrum known as the L-band. Of the 127 nations represented at the conference, only the US, the Commonwealth of Independent States, and India took exception to the agreement.

All three plan to broadcast digitally at the higher frequencies known as the S-band.

"We are present at the birth of a global radio industry," says Pat Clawson, Washington bureau chief of Radio & Records, a weekly trade publication. And "US competitiveness in broadcasting was dealt a staggering blow.... The Third World will have the most advanced telecommunications ability in broadcasting probably a decade before the US."

US backers of DAB were more sanguine. "We are elated," says Martin Rothblatt, chairman and chief executive officer of Satellite CD Radio Inc. and a proponent of the technology. "Most people's view is that the biggest winner at the WARC was DAB." Building a system for DAB

The next step is to build a system to take advantage of the technology.

DAB offers superior sound because it is based on a digital signal rather than the analog signal of AM, FM, and shortwave radio. There are two ways of broadcasting digitally: from land and from space.

A European consortium, known as Eureka-147, is taking the more conservative, land-based approach. A radio station would beam its digital signal from a broadcasting tower with a range similar to television or FM radio station.

Here in the US, Ron Strother, president of Strother Communications Inc., is pushing a similar land-based approach. The difference is that his system would be carried in the current FM band of the radio spectrum. Many radio broadcasters prefer this approach, because it would allow them to offer a CD-quality signal in addition to FM and AM.

"Down the line we will have a hybrid system" of satellite and terrestrial DAB, he says. "But I think because of its cost we could implement terrestrial digital audio far more quickly in this country."

Other US entrepreneurs, such as Mr. Rothblatt, advocate the more ambitious approach with satellite technology. By beaming digital signals directly from a satellite to a receiver, a radio station could blanket a nation or even a continent. Satellite system preferred

The advantage of satellite DAB is that by the turn of the century, a motorist theoretically could drive from Nome, Alaska, to Santiago, Chile, and listen to the same station at the same frequency, Mr. Clawson says.

Another key advantage is that by degrading the signal to FM or even AM quality, a broadcaster with a single satellite could offer hundreds of channels to an entire country. This could be especially helpful to developing nations looking for an inexpensive way to create a national telecommunications infrastructure.

But the US may be cutting itself off from this global market if it concentrates on developing receivers and satellites for S-band, while the rest of the world is broadcasting on L-band.

The Bush administration adopted the S-band to protect the Defense Department's use of the L-band for aeronautical flight-test telemetry. Because of decreased power requirements, L-band is 25 percent to 50 percent cheaper to broadcast than S-band, according to data from NASA's Jet Propulsion Laboratory.

The US satellite technology faces other obstacles too. The National Association of Broadcasters in the US argues that regional and national satellite broadcasts could kill the appeal of local radio stations. A task force of the association has suggested that radio stations beat satellite broadcasters to the punch by using a land-based system.

Another barrier is the consumer market itself. Listeners would have to purchase a new kind of receiver to pick up the digital broadcasts. Initially, at least, these receivers would cost around $300, estimates Nasser Golshan, a system engineer for the digital satellite program at NASA's Jet Propulsion Laboratory.

Rothblatt's company, Satellite CD Radio, plans to launch two satellites in 1995 pending the Federal Communications Commission approval of the company's license.

Satellite CD Radio proposes to offer a subscription radio service, much like cable television today. Consumers would pay $5 a month and receive 30 noncommercial stations with no advertising. Most of the stations would broadcast CD-quality radio, although the company hopes to include a news channel similar to the format of public radio stations.