In a 28-page notice on digital audio broadcasting (DAB) issued Monday (Nov. 1), the FCC stopped short of endorsing in-band, on-channel (IBOC) systems designed to allow the simultaneous broadcast of analog and digital signals without disrupting existing services. Still, the notice stressed that "the catalyst for this action is the progress of in-band, on-channel DAB technology.

"IBOC DAB systems have not been conclusively proven to be technically viable at this point in time, yet great strides have been made and the systems certainly hold real promise," the FCC notice stated.

Most observers praised the FCC action. "We're generally encouraged by the FCC's notice," said Matt Swanston, manager of communications for the Consumer Electronics Association (Arlington, Va.). The group has pressed the FCC to select a system that offers "quality, coverage and compatibility" with existing analog systems, Swanston said. If IBOC meets those requirements, CEA would support it, he added.

The group also endorsed an FCC proposal to provide new spectrum for DAB services. One option calls for using broadcast channel 6 (82-88 MHz) for the new service. New spectrum means fewer technical tradeoffs in designing a national digital radio system, Swanston said.

Lucent Technologies (Murray Hill, N.J.), the leading proponent of IBOC digital radio technology, said the FCC action represents a set of "design objectives" for launching digital radio services. "This is a very positive step in terms of initiating the rule-making process," said Suren Pai, president of Lucent Digital Radio. "The FCC has put a stake in the ground" for launching a nationwide DAB system.

USA Digital Radio Inc. (Columbia, Md.), another IBOC proponent, said the FCC's action will hasten deployment of digital radio. Robert Struble, USA Digital Radio's president, said IBOC's ability to provide new ancillary services along with digital audio sound bodes well for the technology as the FCC decides which approach to take.

The National Radio Systems Committee and IBOC proponents agreed earlier this year to begin submitting laboratory and field test results to the FCC in mid-December. Pai said lab and field testing has focused on audio quality, coverage equivalent to analog systems, immunity to interference and avoiding interference with existing systems, implementation costs — including development of low-cost receivers — and design goals.

Among the design issues, Pai said, is designing DAB systems that operate within existing AM/FM "emission masks," or limits, on signal power. FCC rules impose limits on signal power inside and outside a station's assigned channel.

Struble said USA Digital Radio is conducting field tests in New York, Washington, D.C., Baltimore, Cincinnati, Ohio, San Francisco and its Maryland headquarters. He said the company was pleased that the FCC endorsed the testing process established by the National Radio Systems Committee, which acts as the primary standards-setting body for digital radio.

Along with evaluating IBOC and other systems that would use new spectrum, the FCC review will consider whether a mandatory digital radio transmission standard is needed before the service is launched. IBOC proponents argued in earlier comments to the FCC that a mandatory transmission standard is needed since the radio broadcast industry is unlikely to develop one on its own. It also argued that a transmission standard will provide stability as the new market develops.

"We feel it is very important to select a single standard," said Lucent's Pai, adding that many competing interests must be reconciled before the technology can be implemented. "We don't want to repeat the mistakes of AM stereo," Pai said, referring to a failed attempt to launch a new radio service in the 1980s.

The FCC tentatively concluded in its notice that "the public interest compels a commission role in the development of DAB transmission standards" in cooperation with industry.

Industry comments on the FCC notice are due by mid-January.