Nautel-Digital-Radio-Showcase-Hal Kneller
Hal Kneller is a 40 plus year veteran of the broadcast industry working both as an engineer for WGCU, WGSM, WCTO, WPAT as well as owner/operator of five of his own stations.
Hal is a past International Sales Manager for Europe for Nautel. He also worked for iBiquity Digital Corporation as Director of International Broadcast Development where he played a pivotal role in the promotion of Digital Radio.
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Rich Media Features


by Hal Kneller


Welcome to Digital Radio Showcase, a regular column featuring the latest technical news and information regarding in-band digital radio solutions including HD RadioTM technology and Digital Radio Mondiale (DRM).

Digital Radio Mondiale (DRM and DRM+) has been in the news of late. Following the extension of the DRM standard from 30 MHz up to 174 MHz, (VHF standard is called DRM+) and testing of DRM+ technology in Germany and France, the Brazilian Ministry of Communications invited testing of both DRM for medium/short wave and DRM+ in their country. Brazil is exploring radio digitalization, with HD Radio technology and DRM being the primary contenders. In a future issue, I hope to present some of the Brazilian test results which have to date, not been made public (for either the HD Radio or DRM tests).

While HD Radio broadcasting has been on about 25 stations (both AM/FM) in Brazil for about 5 years experimentally, the Brazilian government has been looking for a standard which can apply to all of their broadcast bands (including short-wave), hence their enhanced interest in DRM. Recently a group of Brazilian community broadcasters wrote an open letter supporting the DRM standard while there is split loyalty between commercial broadcasters as to the preferred approach to digitalization.

Medium wave and short wave DRM tests were undertaken last year, and this year Nautel has provided equipment for the DRM+ testing for both low power and high power trials in Belo Horizonte and São Paulo. Currently, Nautel is the only manufacturer of DRM+ transmitters.


Left: View from the transmitter site at Belo Horizonte, Brazil. Right: Participants making broadcast history in Brazil.

The DRM Consortium has just published a new Broadcaster Users Guide which is available both in book form (I can mail you a copy upon request) or as a download from This is full of both technical and non-technical information about the technology. Speaking of their website, DRM recently rolled out an all-new look so please check it out at

Both DRM and HD Radio technologies offer a suite of additional rich media features beyond digital audio. Last issue, I promised an update of some of these new features in the HD Radio system. Recent announcements from WJFK in Washington, DC and WKSU in Kent, Ohio unveiled the first use of the HD-4 multicast. This represents three independent program streams, plus the required HD-1 simulcast of the FM analog signal. The iBiquity software version 4.3.x is required to operate the HD-4 in a station’s Importer. However, we recommend that stations simultaneously install the same software release on all of their related equipment (Exgine, Exporter, and Importer). Nautel has tested all of its current and past products for full compatibility with the latest versions, but if you use equipment from other manufacturers, please consult with them prior to making an upgrade. Currently, to operate HD-4, the HD-1 through HD-3 must be in the MPS and HD-4 in the Extended Hybrid, using MP3 operating mode.

Another nice enhancement to users operating the current software is that multicast audio streams as low as 16 kb/s may now broadcast true stereo audio. Prior software limited anything below 32 kb/s to monaural. I am told by a reputable “golden ears” that the audio quality and stereo is quite good at 24 kb/s.

Although we’ve been hearing about real-time navigation and traffic guidance via HD Radio digital data services, and both the BTC (Broadcast Traffic Consortium) and Clear Channel’s Total Traffic Network have been rolling out transmissions, receivers have been scarce. Recently the JVC KW-NT3HDT was introduced for after-market automobile in-dash use.

Another useful function is the new Electronic Program Guide recently captured from the Boston-Providence market tests. Future iterations of this technology will permit storing in the background (or when receiver is off) with later play-out analogous to a DVR.

Album art, station logos or even client commercial logos will be able to be shown on the front of future HD Radio receivers via a feature iBiquity calls “object code transmission”. While currently stations may transmit these services, only the HD-4 is currently receivable on the bulk of the HD Radio receivers currently in the field. New products are required to support these multimedia graphics and traffic displays. Broadcast automation systems may be able to insert the object codes into the data transport for display, or third-party applications may be utilized, while traffic information is sent via IP network to the Importer from the data provider.

Finally, iBiquity is releasing a modification to the AM HD Radio system called the Reduced Bandwidth MA-1 mode. This will permit a reduced self-interference operation which disables carriers closer to the host analog frequency. It will also allow greater positive peak modulation and the use of the full NRSC audio frequency range on the host analog station. The bit rate is somewhat reduced (20 kb/s rather than 36 kb/s) and parametric (synthesized) stereo is provided, along with a slightly reduced audio frequency response.



Next issue I will examine some of the enhanced features of the DRM system, and Conditional Access for HD Radio multicasts, perhaps coming to a radio near you fairly soon.

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