Initial All-Digital AM IBOC Tests Completed; Results Being Digested

Initial all-digital AM IBOC tests are done, for now. However, more tests are anticipated for this calendar year.

Members of the Digital Radio Subcommittee of the National Radio Systems Committee received a briefing on the tests at last week’s CES.

Indoor tests were conducted using an Insignia Narrator receiver. Mobile tests were also conducted, with the all-digital signal turned on and off. The test station was CBS-owned WBCN(AM), Charlotte, N.C., a 10 kW day/1  kW night nondirectional. The tests were conducted in late November/December 2012.

Participating in the test project were engineers from NAB Labs (including broadcast engineering consultant Dennis Wallace of Meintel, Sgrignoli and Wallace), CBS Radio and iBiquity Digital, with assistance from Harris Broadcast Communications and Kintronic Labs.

One source told me initial results looked positive while another said the results really haven’t been digested yet. The aim of the testing was to verify whether the AM signal coverage and robustness are improved with an all-digital signal and to quantify any change.

While the FCC approved the implementation of the so-called “hybrid” HD Radio technology in 2002, it’s been some 10 years since there was any testing of the all-digital AM IBOC system. Should the agency ever approve implementation of all-digital AM IBOC, there would first need to be data available to the agency on the technology’s performance.

IBiquity officials recently told me they’re making incremental improvements in the system, including working on better antenna solutions for AM.

I hear there will be a paper on the AM all-digital testing at the spring NAB Broadcast Engineering Conference from David Layer, senior director, Advanced Engineering, NAB.

Going all-digital with AM is reportedly one of several AM technical improvements mentioned in a report from the NAB Technology Committee to the NAB board.    

NAB Labs is looking for other stations on which to test the all-digital AM system in 2013.


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Comment List:

I have HD receivers. Why wasnt the public notified? I would have loved to tune in to seee what HD DX sounded like. Typical Ibiquity PR screwup. The commercials are all stupid,non informative ,surreal, AMEBAS? DIGITAL LIVES? NOw a stupid commercial less than 3 seconds..." HD radio, a good deal more"....WOW! IM SOLD!!
By Lou Arroyo on 4/20/2013
AM IBOC is simply NOT practical. If the modulation were FM, then it would have a chance. However, in the present scheme, there is no way to cancel extreme pulse noise. There simply is no advantage, in the twenty first century, to still be using modulation schemes that are subject to pulse interference. This technology is DEAD..STOP BEATING A DEAD HORSE...
By Tommy on 1/17/2013
You might want to include 0 stars for articles like this.
By Bob Young on 1/17/2013
The all digital AM test should be conducted at the low, mid and high ends of the AM band. Digital AM should be tested on complex directional arrays (like WXYT) as well as on the omni 'graveyard' channels such as 1230KHz. Test it on a dozen stations and this time notify listners so that they can comment on the signal on portables and in their cars as well as both day and night patterns.
By John Pavlica on 1/17/2013

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