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Sound from the skies

As one of two companies with an FCC license to provide subscription-based digital satellite radio, XM Radio-formerly American Mobile Satellite Corp.-has a lot of planning under way.

By second quarter 2001, XM expects to transmit up to 100 digital channels directly to cars and homes via two high-powered satellites produced by Hughes Space & Communications and Alcatel. To supplement the signals, XM will erect a terrestrial repeater network designed by wireless engineering and design firm LCC International. Chip sets for XM-compatible radios will be manufactured by STMicroelectronics.

The lease has been signed for XM's 120,000-square-foot digital-distribution center at Eckington Place in Washington, D.C., leaving station engineers and associates the task of building the underlying technical distribution infrastructure.

"I wouldn't say it's going to be the largest digital facility for radio in the world," says XM Vice President of Broadcast Operations Tony Masiello. "But in the United States, this will be one of the largest digital radio facilities, if not the largest."

The center will contain 56,000 square feet of studio space in 82 separate rooms, from performance studios that are over 2,500 square feet, to 84-square-foot "assembly rooms" for XM's automated "virtual channels." For virtual channels, the music in the database is programmed in advance and the production elements are pre-recorded. XM is careful to point out that these virtual channels will sound "very live."

Masiello says XM will have at least 14 full-blown production studios, including eight air studios dedicated to live DJ programs and six talk studios that can handle a host, six guests, call screeners and producers. There will also be a 2,500-square-foot performance studio for live music.

The central nervous system of the facility, according to Masiello, is a digital routing system made by Klotz Audio Interface Systems. The system features work surfaces that look like traditional radio audio consoles. Components such as routing switcher control heads and intercoms can be plugged into the frames, which will be distributed throughout the facility.

Another key piece of the digital infrastructure is a Radio Systems Inc. StudioHub, a digital-ready pre-wired cabling system that utilizes CAT-5-rated shielded twisted-pair cables to rout both analog and digital audio, although all of the audio at XM will be digital, AES/EBU-compliant.

Renovation of the facility started in November and should be finished by the end of this year. The technical operations center is already constructed, and pre-manufactured studios should be delivered for installation at the end of this month.

XM is purchasing modular studios from Acoustic Systems Inc. of Austin, Texas. Modular studios are being used because they can be delivered quickly but also because they will provide consistent quality of sound.

Choosing the Klotz digital routing system has been the most important equipment decision to date, Masiello says. What has not been decided is the storage and management system for the XM music library. All of the music and production elements will be stored digitally and triggered by a DJ or played back based on a schedule in the virtual channels. XM is looking at storage of approximately 3.5 terabytes of data, or 700,000 titles.

Most day-to-day editing will be handled by the digital-audio system to be specified by XM. Each of the 14 production studios will be equipped with high-end ProTools NT digital-audio workstations in addition to the Klotz console.