Digital radio promises to merge digital audio and data broadcast streams for a host of receivers, from car radios, alarm clocks and Walkman products to PCMCIA cards, Palm Pilots and cellular phones. As the Federal Communications Commission gears up for U.S. digital radio deployment, key technology developers hoping to capitalize on the nascent market opportunity are rushing to ready approaches that could vie for status as the domestic standard.

Several consumer OEMs are expected at CES to announce partnerships with proponents of digital radio and to show early implementations in private demonstrations. The National Radio Systems Committee (NRSC), which sets standards for the radio broadcast industry, is also scheduled to meet here in conjunction with CES to determine where development and testing efforts stand.

Three companies-USA Digital Radio Inc. (Columbia, Md.), Lucent Digital Radio (Warren, N.J.) and Digital Radio Express (DRE; Milpitas, Calif.)-have been touting their respective versions of in-band, on-channel (IBOC) digital audio broadcast (DAB) technology for selection as the U.S. terrestrial DAB standard. Spectrum efficiency is IBOC's biggest attribute: Federal regulators are pressing for IBOC since it would use existing AM/FM frequencies to broadcast digital audio simultaneously, conserving other portions of the spectrum for new wireless applications. If deployed, an IBOC-based digital radio standard promises CD-quality sound and such new services as data broadcasting.

The FCC, which issued a notice of proposed rulemaking in November to consider terrestrial DAB, will play a key role in standards development along with the National Radio Systems Committee. The FCC's schedule for reviewing IBOC proposals called for proponents to submit laboratory and field test results to the NRSC by Dec. 15. Lucent Digital Radio informed the committee it wouldn't make what president and chief executive officer Suren Pai called an "arbitrary" deadline, and the group now expects to hear from Lucent at its next meeting on Jan. 8 in Las Vegas.

But USA Digital Radio, founded in 1991 by Westinghouse Electric Co., CBS and Gannett Co., and Digital Radio Express announced in mid-December that they would join forces to speed development of USA Digital Radio's IBOC system. DRE will focus on datacasting applications. The partners are targeting an IBOC system based on the MPEG-2 Advanced Audio Coding (AAC) algorithm. AAC is also being considered as a codec for Internet music and digital TV applications.

USA Digital Radio and DRE delivered laboratory and field test data to the NRSC and FCC by the December deadline in a move that "confirms that we are ahead," said Bob Struble, USA Digital Radio's president and chief executive officer.

Lucent's Pai took issue with the testing procedures. For one, the current tests compare IBOC systems with FM radio, but if the proposed requirement for IBOC is CD-quality audio, "the IBOC system should be compared to CD," Pai said. "To demonstrate how much better one's IBOC system is than FM is meaningless." Further, the NRSC thus far has not required testing under suboptimal conditions, so the tests do not reflect "the real world," Pai said.

Lucent Digital Radio is in discussions with the NRSC to amend the testing procedures. The company wants to see the creation of a common test platform, under which the results of tests done by the same labs and field tests operated by the same radio stations would be compared. "Unless you are comparing to apples to apples, we believe presenting data to the NRSC is not meaningful. We need to do the right thing here," said Pai.

NRSC chairman Charlie Morgan said the group's key criteria for judging IBOC systems will be a significant improvement in audio quality over existing AM/FM systems. "If it's not significantly better, then no standard," he said.

But the group has yet to define what "significantly better" means. Signal quality and immunity to multipath interference will be considered, but "no one has put their finger on it," Morgan said.

Efforts to pin down the definition and review the proposed IBOC systems are expected to shift into high gear this year. "We will know sometime during 2000 about whether an IBOC system will work," Morgan predicted.

Proponents said IBOC stations could be operating as early as the second quarter of 2001 if a transmission standard is approved. Struble said radio stations could be up and running by the end of 2000, with the first broadcasts following six months later. He pegged transition costs, including the addition of digital exciters, at between $30,000 and $200,000 per station. No new towers or antennas would be needed to begin digital radio broadcasts based on IBOC technology.

But, Struble added, "We still have another 12 to 18 months of hard work ahead of us."

Looking skyward

Lucent Digital Radio, spun out of Lucent Technologies as an independent company to develop IBOC technology for AM and FM broadcasting, has established a corporate mission that seeks to go beyond winning the terrestrial digital radio race. "Our goal is to optimize our core Perceptual Audio Coder PAC technology for satellite, AM IBOC, FM IBOC and the Internet," Pai said.

Further ambitions include entry into the semiconductor business to offer a PAC-based digital radio receiver platform on a chip.

PAC is an audio compression algorithm originally developed by Lucent Technologies Bell Labs to compress audio for transmission or storage. Lucent Digital Radio is tailoring PAC for a variety of applications. Pai envisions next-generation PAC-based radio receivers that would receive satellite broadcasts and Internet music as well as terrestrial digital and analog radio broadcasts.

Though no IBOC technology has yet emerged as the U.S. terrestrial digital radio standard, Pai said his company is making steady progress on its PAC implementation. Early last month, Lucent Digital Radio announced that it had licensed PAC to XM Satellite Radio for use in the latter company's satellite radio service.

XM Satellite Radio received an FCC license for satellite radio service two years ago. Getting the company to sign on to Lucent Digital Radio's PAC was "really a big step" for the technology, said Pai.

Lucent believes that the business models of satellite and terrestrial radio broadcasters will overlap rather than directly compete, allowing the broadcasters to provide complementary services. From a system vendor's standpoint, what "ultimately" makes sense is to build "one receiver on a car to receive both satellite and terrestrial radio services," said Pai. "After all, it can only cost so much, and it has only so much space."

That's where Lucent Digital Radio hopes to come in. Pai envisions his company's role as a key supplier of a standardized component based on its audio codec.

But rival USA Digital Radio said it will focus for now on terrestrial broadcasting. Satellite broadcasting "will happen if the market wants it to," said Struble.

While extending PAC's applications beyond terrestrial radio, Lucent Digital Radio knows that it won't get a genuine break unless it successfully demonstrates the superiority of its PAC-based multistreaming IBOC technology over other IBOC variants. "Within the first three to four months of 2000, we will have conclusively demonstrated our IBOC system to nearly everyone's satisfaction," Pai promised.

Lucent claims that it has dramatically improved its originally proposed IBOC system by developing a multistreaming PAC. Multistreaming 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. The streams can be re-assembled at the decoder in any combination to provide sequentially higher-quality audio. When all four streams are combined, the original audio is recovered.

With the multistreaming technique, the system continues to operate by constantly switching to the highest-quality combination of streams available, according to Lucent. In essence, it improves signal robustness to first-and second-adjacent-channel interference, significantly extends the range of digital signals and emulates the graceful degradation characteristics of analog signals at the edge of coverage.

"The biggest advantage with the multistreaming technique is that radio stations don't have to fall back on analog services," Pai said.

Lucent has the results of field tests conducted earlier this year using the older, single-streaming IBOC system. While the multistreaming signals are broadcast today from WPST's Trenton, N.J., transmission tower, Lucent Digital Radio is still "refining" its receiver design, according to Pai. Still, the company holds high hopes for multistreaming because "we've already done testing based on the single-streaming IBOC, and we are aware of its problems," said Pai.

Lucent's competitors, however, remain skeptical of multistreaming. USA Digital Radio's Struble said the approach remains risky for several reasons, including interference problems and the inability to fall back on analog services if the digital signal is lost.

"We just don't think multistreaming is going to work," he said.