A myriad of diverse topics can only begin to address the changes in technology that affect broadcasters. From man-made noise to advances in content management and transmitter energy conservation, the Tuesday morning sessions at the upcoming NAB Show offer insight to the ever-evolving field of radio broadcast engineering.
Milford Smith, VP of engineering for Greater Media Inc., chairs this group of sessions, which explore the progress in various technologies that affect all radio broadcasters.
This image from Chuck Kelly's presentation shows decreased coverage area for a Class A FM station with a 17 dB noise floor increase.
"Energy Conservation in AM Broadcast Transmitters Using Carrier Control Algorithms" — While newer model AM transmitters offer high overall efficiency, an additional energy conserving method involves a technology long employed outside the United States, especially on transmitters with powers in excess of 100 kW.
"Since the majority of carrier and/or sideband power transmits little or no information, employing carrier control algorithms can result in possible energy cost savings in the range of 10 to 50 percent with some trade-off in audio quality or coverage," claims Tim Hardy of Nautel.
He will explore this technology, which is new to engineers in North America. Electric costs have continued to rise with engineers and designers looking for new ways to reduce consumption and maximize savings.
"Got Green? An Engineer's Guide" — When we think of "green," most of us define it as recycling and using recycled materials at home. Expanding this process to the broadcast facility using corporate social responsibility can result in a considerable amount of materials such as paper, plastic, light bulbs, batteries, glass, liquids and metals being repurposed or recycled instead of ending up in a landfill. Using car pools, public transportation or bicycles helps save our environment. Drafting and implementing a plan at the studio and transmitter sites can result in a cleaner, greener environment.
Such a plan must start at the top management level and filter down to every employee. With the shortage of landfills, mandating recycling such as using both sides of a sheet of paper to using energy-efficient lighting and environmental systems every employee can contribute to a cleaner, greener environment.
Technologies broadcast engineers can use in this effort are examined by Nolan Stephany of WXXI Public Broadcasting Council and Andrew Janitschek of Radio Free Asia. How a facility can earn the Energy Star and save on energy costs is a strong incentive to start now. In 2008 Radio World launched a Green Radio series which examined actual examples of conservation in action.
"The Application of Software-Defined Radio Technology to Multi-Standard Waveform Generation for Television and Radio" — Tradition makes one think of hardware when addressing the topic of radio receiver design. With the multiple of waveforms employed by broadcasters, manufacturers have turned to software defined radio (SDR) platforms.
This approach provides the maximum flexibility by the use of software framework in combination with a hardware composition. Broadcasters formerly employed analog audio processors with hardware controls (pots) for parameters such as audio levels, timing, ratio, etc. Digital based processors employ software to accomplish these same adjustments. The benefits are repeatability of adjustments and the ability to accommodate new technologies and enhancements by software upgrades opposed to hardware replacement.
Kevin Berndsen of Harris Corp. addresses the advantages and implementations of the software framework, as technologies borrowed from computing and server domains provide flexibility in receiver design that keeps pace with evolving transmissions waveforms.
"Using the Resource Description Framework (RDF) to Simplify Content Management" — Content management is becoming ever more important in today's broadcast station. Most stations have a presence on the World Wide Web. This can be a page with streaming audio, podcasts, news and features, contests, links to advertisers and interactive content.
Managing and organizing these various delivery systems can be simplified by the use of Resource Development Framework (RDF), a computer language for representing information about data resources on the Web. Content or Digital Asset Management can be tedious in a multistation or cluster environment. By implementing the Semantic Web approach, computers will be able to furnish people information that will be thorough and on target of their needs. This approach can also be applied to the broadcast station by managing libraries and other sources of information to be presented to the listener/viewer.
David Baden, the chief technical officer of Radio Free Asia, and Ronald Reck of Rrecktek will demonstrate how to manage content effectively. As an example for the need of content management, Radio Free Asia broadcasts 35 hours per day in 11 languages seven days per week on air and Internet.
"Implications of Increasing Man-Made Noise Floor Levels on Radio Broadcasting" — Most broadcasters strive to provide the strongest and highest quality audio to their listeners. The effect of raising the noise floor is decreasing coverage. Man-made noise comes from many sources: AC power lines, light dimmers, microwave ovens, touch operated lamps, high-speed digital circuitry in computers, and microprocessor controlled devices can increase the noise floor dramatically. Microprocessor clocks operate in the range of several kilohertz to hundreds of megahertz, which can affect AM and FM reception.
Nautel Director of Sales Charles Kelly is slated to examine sources of noise and studies conducted in India and other areas. He'll show an example of a Class A FM station's coverage reduced by 71 percent by a 16 dB increase in noise floor, and address remedial options.
"Same Basket, Different Eggs" — Broadcasting live events for terrestrial radio used to be simple. An RPU or phone line was employed to relay audio from the event to the studio. New technologies such as HD Radio, Internet, cellphone and other devices require care in how the product is ultimately received by the listener.
Alex Kosiorek, director of recording services for the Cleveland Institute of Music, examines various technologies that are employed to quality content in this presentation.
"Producing content for delivery to today's receiving devices requires care. One major concern is cascaded digital algorithms. With digital technologies employed in several steps in the transmission and editing path, degradation can result," he says.
Processing for different codecs, ensuring consumer devices do not experience digital level overload, and simplifying the process will be discussed in detail.
"What you can do on the front end to obtain quality at the back end is the goal." In today's era of surround sound, content delivery to cellphones as well as over-the-air and Internet requires a strong bond and sharing of experiences between the broadcast engineer and IT specialist.
The real world
The afternoon sessions, "Antenna Solutions and Case Studies for Radio," aim to provide an engineer with experiences from those directly involved, said session chair Andy Laird, VP and chief technology officer for Journal Broadcast Group.
"Experience is one of the best learning tools, and the professionals relating theirs will enable those in the audience who face similar challenges to be well informed on how to resolve them in a timely and seamless manner."
"An AM Directional Antenna and HD Radio" — Tom Ray of Buckley Radio, an RW contributor, will describe the directional antenna recently installed at WOR(AM) in New York.
"While a three-tower dogleg array may not seem complex, the antenna system contains traps and complex detuning (including detuning skirts) because of the other AM directionals in the immediate vicinity of the WOR array," NAB states in the summary. Ray will discuss the performance of the antenna system and compromises that had to be made to make the system work on budget.
"The National Radio Systems Committee IBOC RF Mask Measurement Guideline, NRSC G201" — David Maxson, managing partner of Broadcast Signal Lab, relates his experiences on the committee's Digital Radio Broadcasting Subcommittee IBOC Standards Development Working Group recommendation to adopt the latest revision of the NRSC-5 standard, NRSC-5-B.
"It became apparent that there was a need for a 'gold standard,' so to speak, on conducting measurements for measurements of IBOC signals," Maxson said.
"Since measurements are more about implementation of IBOC than about how to make an IBOC signal, NRSC DRB decided that instead of a standard, it would be best to develop a best practices guideline for measuring IBOC signals.
"This presentation will provide broadcast engineers with the background on the collective knowledge and experience that went into the creation of NRSC G-201, a comprehensive guideline for transmitter tests and measuring the actual quality of the transmitted IBOC waveform, using metrics of the digital signal constellations, such as Modulation Error Ratio, or MER."
"Real-World Installation of AM HD Radio" — Installing AM IBOC is not as simple as plug-and-play. Ray Klotz, president and CEO of Sierra Multimedia Inc., relates his experiences of such an installation at KFAQ(AM), Tulsa, Okla., a nondirectional day, three-tower directional night antenna system.
The towers have 7 foot square faces and the phasing/coupling system is of 1988 vintage. Klotz will talk about preparation prior to the project, the installation itself and post-installation measurements to prove proper operation; he'll also talk about antenna system requirements as well as transmitter and field measurements.
"The lesson learned here can be stated in one sentence: If you are going to install AM IBOC, do your homework and pay attention!"
Two experiences in the installation were spectrum analyzer input overload resulting in the display of spectral regrowth that, in fact, was not present in the field and differences between the factory adjustments and those required in the field.
Myron Fanton of ERI will discuss the case study of a multi-station combined building-top analog/digital antenna. Shown, a worker (lower right) prepares the structure for another bay. "HD Radio Implementation Case Study: Dual-Polarized Master Antenna" — With the possible increase in FM IBOC power, many antennas and/or transmission lines may not be capable of safely accommodating the higher levels. This is especially true of multi-station installations.
One case study of a multi-station combined building-top analog/digital antenna is discussed here. Myron Fanton, chief engineer of RF technology for Electronics Research Inc., presents details of the dual-input antenna. He'll talk about special requirements of low downward radiation and radome enclosure. He offers the new development of antenna combining using dual polarized antennas to achieve 10 dB injection as an economical option for the increased IBOC power, and present an examination of the antenna design, installation and operation.
"Easing the Transition to AM IBOC: Tools and Techniques to Help the Broadcaster" — In AM IBOC installations the engineer has two goals: Achieve good receiver lock while maintaining spectral regrowth within FCC limits.
Research Engineer Brian Walker of Nautel says, "I will discuss the challenges in achieving spectral compliance with AM IBOC, and what can be done to help solve them. A modern AM transmitter can incorporate several tools for the broadcaster. For troubleshooting, an integrated spectrum analyzer and real-time impedance measurement can help with tracking down problems with the antenna without needing to go off the air."
Design implementation of precorrection in the transmitter and optimization of the load are important ingredients in transmission of the optimum signal quality.
"Assuming the load has been adjusted to be as symmetrical and ideal as possible, the transmitter must adjust for its own distortions and any remaining imperfections in the load. Amplitude and phase distortions in the power amplifiers can be characterized and removed by using precorrection. The frequency response of the transmitter when loaded by the antenna can be measured and flattened with adaptive filtering to prevent any mixing distortions," he said.
"High-Level IBOC Combining Using Filters" — One of the methods employed to transmit FM IBOC is high-level combining. Director of Filter Products for Myat Derek Small compares traditional techniques to the lossy directional filter approach. Differing filter responses are employed to adjust the analog and digital path response throughout the system. Factors such as efficiency, loss and delay variations are examined with their effects on the signal shown.
Kintronic will profile the first installation of its low-profile KinStar antenna at KCST(AM) in Florence, Ore.
"The Inaugural Installation of the First KinStar AM 'Green' Antenna" — AM broadcasters are often faced with restrictions on tower height. These may be for aesthetic or aeronautic reasons.
A solution to this problem is offered by Tom King, president of Kintronic Labs Inc. The low-profile KinStar antenna has a height of 75 feet at 1000 kHz. The first KinStar installation at KCST(AM) in Florence, Ore., will be shown. This installation employed wooden utility poles and no concrete, qualifying it as a "green" installation in a forest background.
The FCC has adopted simplified application procedures for nondirectional KinStar antennas. They have been shown to exhibit broadband characteristics and coverage comparable to taller quarter wave radiators. The KinStar was developed by Star-H Corp. and is manufactured by Kintronic Labs.