Lucent Digital Radio (Warren, N.J.) and USA Digital Radio (Columbia, Md.) said they will continue to vie to define a terrestrial digital radio standard, since their respective systems and supporting silicon are still in the early design and test phases. But the two will also have to contend with digital satellite radio schemes which are set to launch later this year, as well as with the expected rise of cellular- and Web-based digital radio.

Based on preliminary tests of the competing systems, "it is reasonably probable that IBOC will work," Charlie Morgan, chairman of the National Radio Systems Committee (NRSC), said at an NAB panel on implementing digital radio. The question that awaits further test data, he said, is whether IBOC is superior to current AM/FM broadcast quality.

One way to speed that process would be to merge the IBOC camps into a single team reminiscent of the HDTV Grand Alliance, he said. "If there ever was a time for a 'grand alliance,' the time is now."

Both IBOC proponents held their cards close to the vest on a possible merger of their development efforts. Robert Struble, USA Digital Radio's president and chief executive, called digital radio a "winner-take-all" contest and said "each side will respond accordingly." But he added that "we know never to say 'never' " on the matter of a possible alliance down the road.

Suren Pai, president and chief executive officer of Lucent Digital Radio, said the NRSC efforts "have not progressed far enough to reach the stage . . . for us to sit down at the same table with USA Digital Radio to start negotiations on making IP [intellectual property] deals and economic splits. We first need to have a common test platform on which we can do comparative evaluations. That process is just starting."

The Federal Communications Commission, which launched an inquiry into digital radio last November, has yet to endorse IBOC but has called the technology "promising," largely because it uses existing AM/FM bands. "We have to be sure [IBOC] works," the FCC's Keith Larson said this week, meaning that the scheme must be compatible with existing analog radios, provide comparable coverage and be affordable.

USA Digital Radio's Struble said third-party testing of the competing systems is being handled by the Advanced Television Test Center (Alexandria, Va.), the facility that tested HDTV equipment.

Regulators attending NAB were repeatedly pressed on their timetable for a digital radio transmission standard. All said they would like to see a single standard in place by year's end.

Same spectrum

Radio stations may face tougher technical challenges in going digital than did their terrestrial TV-broadcast counterparts, which received 6 MHz of free spectrum from the FCC to make the transition to digital broadcasts. With no new licenses for spectrum or new leases for tower sites, the radio stations will use IBOC to offer digital and analog radio services simultaneously over the currently allocated analog spectrum.

The platforms designed by USA Digital Radio and Lucent Digital Radio differ largely in their audio codecs and in their methods of laying the digital stream over analog. USA uses the Advanced Audio Codec; Lucent uses proprietary perceptual audio coding (PAC), designed by Bell Labs.

Further, the USA Digital Radio scheme lets radio stations fall back on analog services when mobile vehicles go out of the digital radio service coverage area. Lucent developed a method called multistreaming that breaks audio information into multiple packets (streams), each of which can stand alone and provide quality audio.

Audio coding operating at 128 kbits/second, for example, can be broken into four 32-kbit/s streams under the Lucent scheme. The streams can be reassembled at the decoder in any combination to provide increasingly higher-quality audio. When all four streams are merged, the original audio is recovered. Lucent says the technique lets the system operate smoothly by constantly switching to the highest-quality combination of streams available. It improves signal robustness to first and second adjacent channel interference, extends the range of digital signals and emulates the graceful degradation characteristic of analog signals at the edge of coverage, the company claims.

USA and Lucent are designing chip sets now for their respective receiver platforms. Lucent Digital Radio designers are working on a prototype in-house but will need to tap a chip manufacturer's ASIC expertise to maximize gate-count and chip-layout efficiency, said marketing director William Casey, adding that the company is close to picking a partner.

Key blocks in Lucent's receiver are RF, channel modulation and PAC decoder. So far, PAC has been ported to Analog Devices Inc.'s Sharc DSP and STMicroelectronics' microprocessor architecture, Casey said.

USA Digital Radio is working with Texas Instruments Inc. and Analog Devices on a low-cost chip set, but Struble said a standard has to be in place "before the price comes down." He said he sees high revenue potential for chip makers, noting that "the chip side is obviously important" to the technology.

New life for radio

System designers and chip vendors indeed sniff a market opportunity in breathing new life into radio by altering the medium's roles and product definitions. At NAB, Struble listed datacasting, digital storage and interactive services as three areas ripe for digital radio applications. Datacasting lets broadcasters offer such program-specific data as the title of a song being broadcast or information on the artist performing it, as well as such program-independent services as stock quotes and traffic updates. Digital storage lets listeners record programs and retrieve them from memory for playback. Interactive services on digital radio could enable e-commerce, for example, by using a cell phone for the return channel, Struble said.

Still, some in the industry doubt IBOC's potential and fret that if the approach does not take off, revenues will flow to satellite-based services. "I see all sorts of problems with IBOC," a Canadian observer said.

Equipment manufacturers are also hedging their bets. Transmitter maker Nautel Ltd. said it is supplying equipment to both USA Digital Radio and Lucent. Receiver manufacturers are also said to be looking into both IBOC systems.

Satellite competition

Satellite service providers Sirius Satellite Radio (New York) and XM Satellite Radio Inc. (Washington) are preparing to launch satellite constellations soon that would provide a national digital radio network.

Sirius would be the first to field a domestic system with the planned rollout of non-commercial, subscription-based service before the year is out, said Robert Briskman, the company's executive vice president for engineering. Three geosynchronous satellites are slated to launch this year, with completion by year's end of such associated system facilities as an uplink earth station, terrestrial repeaters, tracking/telemetry/command stations and vehicle receivers.

XM Satellite Radio will launch its first satellite in November and plans to begin broadcasting in the first quarter of 2001. "We will start full-service operations on May 15, 2001," promised John Wormington, senior vice president for engineering and operations.

Moreover, wireless phone services, such as upcoming 3G implementations, will be well-equipped to allow Web radio and thus could ratchet up the number of radio stations competing with today's established broadcasters. "Make no mistakes," said Lucent's Pai. "If you don't take advantage of digital radio now, and if you don't plan your business beyond the car-radio paradigm, you'll be eaten alive, not just by satellite but also by wireless service providers."

IBOC's proponents said compatibility with the emerging satellite systems is a chip-level issue rather than a system design concern. Struble said future car radios could be equipped to receive both AM/FM IBOC channels and some satellite channels, for example.

Lucent claims its PAC codec plays well in such a universal radio design. Indeed, Pai said that XM Satellite Radio is using the codec and that Lucent is also licensing it for Internet radio.

XM and Sirius have agreed to use an interoperable satellite radio receiver in their second-generation designs, and Lucent has promised to launch a radio that receives both IBOC and satellite signals in time for the second-generation satellite offerings. But the timetable for those rollouts is four years out.