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NAB Sunday in One Word: Digital!

Implications of the FM IBOC power hike are explored, along with other issues

“Digital Radio Advances in Technology,” the title of the Sunday morning NAB Broadcast Engineering Conference sessions moderated by Mike Cooney, vice president of engineering and chief technology officer for Beasley Broadcast Group, sums up the theme of evolving improvements and upgrades to digital terrestrial radio broadcasting.

On the AM side, “New Tools in the AM HD Radio Toolbox” addresses several innovations.

Jeff Detweiler, director of broadcast business development for iBiquity Digital Corp., says the company’s new v4.3 Exciter MPS Framework “has many new features designed to improve the AM digital listener experience.”

These features include a new configuration for AM HD Radio’s primary service mode, or MA1, specifically a core-only mode with single 20 kHz stream with no secondary or tertiary carriers, promising analog at full 10 kHz bandwidth. Additionally, there are new AM HDC codec configurations for talk, parametric stereo and monaural programming.

Other updates include AM HD Radio data support, which now enables connectivity to the Importer; AM HD Radio support for synchronizing audio and data applications; and improved time synchronization between audio and PSD to improve music tagging applications. Another feature is the new XHDR Trigger support in the PSD GEN API to support station logo, album art and synchronized images.

“Each of these new features in the reference exciter software will be discussed, describing how iBiquity’s ongoing product improvement campaign will benefit AM radio broadcasters and their listeners,” Detweiler said.

When and How Will Terrestrial Radio Go Digital in Europe?” is a question to be addressed by Markus Ruoss, founder and owner of Ruoss AG.

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A slide from Jeff Detweiler’s presentation on AM HD Radio technology improvements illustrate a configuration allowing the analog signal to be restored to a full 10 kHz bandwidth while providing stereo digital in a single-stream configuration that is backwardly compatible with existing receivers.
With a variety of available options and a patchwork of various digital radio solutions throughout the continent, factors such as economy, politics and differing technical rules make a single digital solution in Europe unlikely, Ruoss says. A number of distribution platforms are expected. While a transition to digital was expected earlier, the financial crisis has slowed progress, resulting in a longer-than-expected life span for analog.

He’ll talk about navigating the barriers, a solution through a gradual transition and an example of a “yes-but” as opposed to a “no-but” scenario.

One of the features made possible by HD Radio is an EPG. “Electronic Program Guide Field Trial: How HD Radio EPG Works” will be presented by David Maxson, managing partner in Broadcast Signal Lab LLP.

This is intended to explain to engineers, programmers and managers the ease of integrating EPG content to better serve listeners. According to Maxson — who with Steve Riggs coordinated a field trial in the Boston, Providence and Worcester areas — BIA/Kelsey and Broadcast Signal Lab teamed with Unique Interactive to explore the requirements for a radio Electronic Program Guide.

“Radio broadcasters are at a disadvantage to other digital media that have online program information available to the listener at the point of listening — more than just title and artist,” he said. As Radio World has detailed in the past, the EPG project was sponsored by the NAB FASTROAD program.

“This talk explains how EPG services for radio will work. It includes a discussion of the impact of EPG content creation on station workflow, as well as a cook’s tour of how EPG data gets on the air via HD Radio transmissions. Also, as more and more devices become both radio-capable and Internet-connected, rich radio EPG services can be delivered in a complementary way over both media.”

Laboratory Test Results of Digital Radio Technologies: DAB, DAB+, T-DMB Audio and HD Radio” examines evaluations performed in the lab.

Yong-Tae Lee, principal researcher for ETRI, performed tests and comparisons with computer simulations for the purpose of determining which technology is best suited for operation in Korea.

DAB, DAB+ and T-DMB audio were tested for service in the VHF III band, and HD Radio and DRM+ tested for service in the VHF II band. Among the tested items were spectrum mask, phase error, dynamic range and Bit Error Rate performance in the Gaussian and fading channels. Also examined were interference in the co-channel and adjacent-channel scenario and single-frequency network capability testing. Audio quality testing based on the lab work also was performed. Field testing is expected in the next year.

“We believe that these test results will be useful to the countries considering analog FM service conversion to digital radio,” the author wrote in an NAB conference summary.

Digital signal processing is employed in many pieces of broadcast equipment, most notably audio processors. It can also be employed to enhance Digital Radio Mondiale power, resulting in increased coverage.

Digital Power Enhancement for DRM was developed by Transradio. Discussing the details of this process will be Christian Horlle, project manager for digital radio at Transradio in his presentation “Digital Power Enhancement for DRM.”

Afternoon: Focus on FM digital

“FM Digital Radio,” a track of afternoon sessions also moderated by Mike Cooney, brings a focus to FM HD Radio issues. Many, though not all, of the presentations delve into implications of the decision by the FCC to allow higher IBOC power.

“There are consequences to increasing HD power,” said Mike Troje, marketing manager for Continental Electronics. “As with most engineering problems, compromises must be made so a detailed understanding of the issues and their impact on each station must be understood. There is a lot of hype on all sides and we want to peel that away and expose the hard truths. Increasing HD power levels will require a great deal of research on the part of each FM station’s engineering staff.”

His presentation, “Planning for the Increase in Digital Power for FM HD Radio Signals,” examines the “good and the bad” sides of the power increase.

“Preserving the existing analog revenue stream while advancing the conversion to digital will benefit the industry both now and well into the future.

“More specifically we will discuss how increased HD power increases the negative envelope modulation of the hybrid waveform. If the negative envelope gets too close to zero, some receivers such as clock radios and some hi-fi receivers with relatively wide IF bandwidths will cause their FM limiter to fail. This can be a real nuisance on some radios and not noticeable on others with narrower IF bandwidth,” Troje said.

With the FCC approval for an increase in HD Radio power from –20 dBc to –14 dBc, broadcasters have a number of available options to implement this improvement as well as a possible power upgrade to –10 dBc.

Extending Your HD Radio Footprint,” presented by Harris Corp. Vice President of Transmission Research and Technology Geoff Mendenhall, P.E, examines the power increase issue and other topics related to HD Radio coverage improvement.

The power increase “will require more digital transmitter power with greater isolation between the analog FM transmitter and the digital transmitter in separate amplification systems,” said Mendenhall.

Additional topics include RF power amplifier linearity improvement, space combining, common amplification, high-power filterplexers, sharp-tuned RF mask filters, additional HD power with hybrid crest factor reduction techniques, and unequal HD Radio sideband powers to achieve interference reduction. He will also discuss the use of HD Radio gap fillers and translators.

Mendenhall will share results of the industry working group he chaired on a standardized method to measure the HD Radio signal transmission quality.

He said he wants to help the radio station engineer understand facility planning requirements and technology choices to improve a station’s HD Radio signal footprint. “This is intended to be a primer on several methods to improve HD Radio coverage.” The system must deliver a quality signal to listeners in a variety of locations and receivers as well as conform to FCC emission specifications.

Further examining the power increase is “Practical Tools for HD Radio: HD Power Boost, Increased Sideband Levels and More” presented by Nautel Market Development Manager Hal Kneller.

Among his topics are “new technologies that enhance the Peak-to-Average Power Ratio (PAPR) already contained in the iBiquity code. Nautel now incorporates the digital constellations as well as the analog signal to further increase amplifier efficiency and power output. This product is called HD Power Boost. Also discussed are elevated sideband modifications to existing and new products.”

Kneller added, “With the FCC approval of increased HD Radio injection levels, many issues come to the table, and manufacturers are working hard to get information, modifications and support to customers.”

A talk by Henry Downs, vice president of engineering for Mega Industries, will explore “HD Radio, The Way Forward,” intended to guide a broadcaster toward the most effective solution to realize HD Radio in its market.

Given the transmission equipment already in use, the available budget and all other options, an examination of offerings from many manufacturers will assist in the final decision, Downs said. These options include transmitter upgrades or modifications, dual-input antennas and low-level combining.

Two common technologies long employed by analog broadcasters are boosters and translators. The former operate on the station’s assigned frequency, the latter broadcast on another frequency.

Tim Bealor of BE will talk about the benefits to FM HD Radio broadcasters in “Translators and Boosters: What You Need To Know.”

“While boosters still do and always will have limited usage, with the right implementation, they can be a very effective tool,” he said. According to Bealor the most important technology advances are in the exciter, with accurate delays and modulation controls and better synchronization techniques.

“Boosters have limited application, and must be correctly engineered to be successful.”

Putting the IBOC Quality Metric to the Test” examines a newly developed metric aimed at evaluating signal integrity to permit maximum coverage and minimize the amount of error correction in receivers.

“Now all manufacturers and broadcasters have a uniform standard to work from,” said Philipp Schmid, digital design engineer for Nautel Ltd.

The metric is an effort of the National Radio Systems Committee, the NAB, various manufacturers, iBiquity and other professionals.

“In the past, stations installed IBOC equipment, checked the mask and injection level via spectrum analyzer and dealt with things they could hear like audio processing, and assumed the best,” Schmid said.

“Having a uniform standard to work from allows us to evaluate Modulation Error Ratio (MER) separately for data and reference carriers, IBOC carrier amplitude and group delay variations.

“We expect the MER measurements to benefit HD Radio broadcasters by improving signal integrity by permitting exact measurements.”

Tom Osenkowsky is a broadcast engineering consultant and long-time contributor to Radio World.