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IBOC Standard-Setting ‘Temporarily Suspended’ Over PAC Concerns

IBOC Standard-Setting ‘Temporarily Suspended’ Over PAC Concerns

Has radio’s digital rollout hit a pothole?
Standards-setting activity for IBOC has been temporarily suspended by the steering committee of the National Radio Systems Committee’s DAB subgroup.
This development, sources said, puts the onus on Ibiquity to continue to tweak PAC or chose another audio coding algorithm.
Growing concerns about the performance of Ibiquity’s PAC codec on AM at low bit rates has led the steering committee to make this decision.
Also as a result of this action, Radio World has learned, some major radio groups are slowing their adoption of IBOC until the codec issue is resolved, according to NRSC sources.
In a memo to members of the NRSC obtained by RW Online, the steering committee stated: “The NRSC has long considered flexibility to be an important feature of IBOC digital radio systems, and is concerned that PAC operating at bit rates between 36 kbps and 96 kbps (the maximum coding rate used in the hybrid FM IBOC system) could also have quality issues that may need to be investigated by Ibiquity.”
NRSC DAB Subcommittee Chairman Milford Smith stressed the performance of the codec at low bit rates is one problem and that the NRSC still supports IBOC. “The overall system is really great and works well.”
Yet, “Our goal from the start has been to have both an AM and FM solution. We don’t think we’ve got an AM solution.”
Smith and several NRSC sources said the standards-setting process would resume when Ibiquity has demonstrated the problem is resolved.
Ibiquity has two choices: continue to tweak PAC or chose another audio coding algorithm such as AAC or MPEG. Ibiquity used AAC previously, and several NRSC sources said they thought the system audio quality with AAC was better than it is with PAC.
After a recent private demonstration at National Public Radio, several NRSC sources said they found the artifacts on the system using PAC “unacceptable.”
In a statement today, Ibiquity responded: “At this time, we concur with their decision to temporarily delay these efforts until the issue is resolved … we have an on-going improvement plan and anticipate resolution of the AM audio quality issue as soon as possible.”
Kenwood, meanwhile, said it is still prepared to go forward with its receiver launch this summer despite the NRSC action.