Expansion of Channels Is a Global Trend
February 1, 2019
Colwell studied digital radio developments for the NAB Engineering Handbook Kenneth E. Colwell, PhD, CSRE, DRB, CBNT, wrote the chapter on worldwide digital radio systems in the 11th edition of the NAB Engineering Handbook. He is professor of communication and director of the Ambrose Communication Center, St. Ambrose University in Iowa. Radio World: What did you learn in doing your work for the recent handbook? Kenneth Colwell: What I noticed first is that the move to digital radio was often prompted by a need for greater efficiencies: energy usage, spectrum space, number of transmitters and coverage concerns.
the transmitter and receiver technology makes it easy for the audience to access the new programming will be a key factor. RW: How do you think recent developments in digital radio — in the United States and elsewhere — have affected transmitter designs and product planning? Colwell: The digital design development that jumps to mind is the HD Multiplex technology of Philipp Schmid at Nautel. While the digital technologies of DAB and DRM have the capacity for a large number of multiplex channels (well into the double digits), the HD Radio plan in the U.S. is quite Kenneth E. Colwell
The carryover of ideas, philosophies, techniques, technologies, software and hardware from the development of ATSC 3.0 will also, I believe, be an influence for how we will think of the future for digital radio. While the needs of the audience or of the radio programmers were not in the forefront, the move to an all-digital broadcasting plan (soon or in the future) did have its benefits for all parties. Dropping analog transmissions, developing single-frequency-networks and multiplexing multiple audio channels onto a single digital channel all go a long way toward creating the efficiencies desired. Since many of the efficiencies were mandated by governments, it was up to the transmitter manufacturer — the ones in the middle between the broadcasters and the regulators — to find ways to successfully address everyone’s concerns. But their engineering creativity alone wasn’t enough. The demand for multiple audio channels created the demand for more efficient audio codecs, codecs that sounded good and were lean in bandwidth needs. Radio programmers and their audiences will be able to benefit from the potential increase in the number of audio channels available. Instead of a one transmitter/one audio channel scheme, we could now have many more audio channels on fewer transmitters, and more audio channels per transmitter. The demand for more quality programming is certainly there. How
limited by comparison. What Philipp has done is to get us thinking about what we can do with IBOC HD Radio to increase audio channel options, serve different programming and audience needs, investigate an all-digital HD Radio for AM and FM, begin building a database for real-world digital performance and see if a new pattern for FM station frequencies (e.g., 100 kHz spacing) might be a useful future operating scheme. The carryover of ideas, philosophies, techniques, technologies, software and hardware from the development of ATSC 3.0 will also, I believe, be an influence for how we will think of the future for digital radio. Moving away from traditional FM and the sound quality present there, for the radio listener, is a tough sell. Traditional FM sound quality is the standard many digital broadcasts are, and will continue to be, measured against. Range and quality of reception needs to meet or exceed that of the existing analog FM, for the listener. It’s the sound and reception that matters to the listener. They are not moved to listen to the digital based on the sophistication or cachet of being digital alone. But if it’s easy to tune in, sounds great and is available inside and outside the
car, then the listener will remain. Taking the perspective of the listener is just as important a perspective as that of the regulator or broadcaster for the transmitter manufacturer. RW: What technologies or applications are ahead? Colwell: As broadcasters begin to exploit either the HD Multiplex scheme or the other digital multiplex features of DAB or DRM, studio infrastructure will need to be capable of handling, processing, storing and playing back/ streaming out a larger volume of audio channels. Audio over IP will need to be employed in those studios, and transmitter manufacturers are building with an eye toward making the AoIP connection as easy as possible. An end-to-end digital link should be the ultimate goal. There is no doubt in my mind that the desire for an easily updateable standard for TV as presented in ATSC 3.0 will be the way radio transmitters will be designed for the future. Transmitters This article is from Radio World’s ebook “Trends in Transmitter Design.” We’ve now published more than 50 ebooks on a wide range of topics that are of interest to the broadcast technologist or manager including AoIP, next-gen codecs, cloud technology, digital radio, RDS, DRM, translators and more. All are free to read. Find recent issues by clicking the ebooks section under the Resource Center tab at radioworld.com.
of the future will be card cages attached to a power supply, a fiberoptic port, an ethernet port, a USB port and a coax connector. They may even be capable of producing both radio and TV signals simultaneously — as the DVB-T2 standard provides. Virtual radio will be an idea with many different expressions and implementation schemes, but transmitters and studios will no doubt be included. RW: What other questions should we be exploring? Colwell: Thoughts from a user’s perspective: Can the remote control functions already present in the transmitter GUI be expanded to include input from external sources? For example, door sensors, security camera feed, environment control (HVAC) and sensors. Can the exporter and importer I/O be manufacturer neutral? If I have transmitters from different manufacturers, why do I have to have multiple exporter/ importer boxes?
Radio World 1131 - February 1, 2019 issue