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A single standard for terrestrial digital radio is still somewhere over the rainbow. Despite pressure from broadcasters to form an industry alliance, leading developers of the new technology are intent on pursuing their own courses, attendees learned at the 2000 National Association of Broadcasters convention in Las Vegas in mid-April. Executives from USA Digital Radio and Lucent Digital Radio, the two biggest players in the sector, told NAB members that their design and testing programs are still in early stages of development, too soon for accord.

Both companies are working on versions of "in-band, on-channel" (IBOC) digital radio technology, but prefer not to share their work—despite pressure from broadcasters, who would like to see a "grand alliance" similar to the one that was formed around high-definition television. "If there ever was a time for a 'grand alliance,' the time is now," said National Radio Systems Committee chairman Charlie Morgan, speaking at an NAB panel on implementing digital radio. Morgan said early results indicate that IBOC will probably work, but it is unclear if it will be superior to present AM and FM broadcasting techniques.

Broadcasters had hoped to accelerate the new technology by pushing the "hardware guys" into a research-and-development agreement, but such was not to be. The race to establish standards is a "winner-take-all contest," according to USADR president Robert Struble. LDR president Suren Pai stated that, before any alliance can be formed, engineers need to have a common test platform for comparative evaluations, and the process of establishing such a platform has only just begun. The two companies use differing audio codecs and methods of combining the digital stream with analog. USADR uses the Advanced Audio Codec; Lucent uses proprietary perceptual audio coding (PAC) created by Bell Labs. USADR's system provides for an "analog fallback" in that receivers will revert to analog reception when they move out of the digital reception area.

Competition is heating up on other digital-radio fronts as well. Internet-based "Webcasting" is already popular among computer users, and satellite service providers Sirius Satellite Radio and XM Satellite Radio Inc. are preparing to launch satellites to create a national digital radio network. Sirius will put up three geosynchronous satellites this year, and hopes to complete the terrestrial support system by year's end with an uplink earth station, terrestrial repeaters, tracking/telemetry/command stations, and vehicle receivers. XM Satellite Radio will put up its first satellite in November. "We will start full-service operations on May 15, 2001," said XM senior vice president for engineering John Wormington.

Technical obstacles facing digital radio designers are somewhat more difficult than those faced by designers of the digital television system, who were given 6MHz of free bandwidth to play with. Digital radio will occupy the same part of the spectrum as current AM and FM broadcasts, and must be compatible with them. Federal Communications Commission regulators say they would like to see a single standard emerge by the end of the year. The Advanced Television Test Center in Alexandria, Virginia will conduct third-party testing of the competing systems, as it did for HDTV.