HD Radio’s First 15 Years
Gary Liebisch has been in broadcast engineering for over 40 years. Gary joined Nautel in April of 2007, as the Eastern U.S. Regional Sales Manager, has served on the Board of Directors for the Society of Broadcast Engineers from 2008-2012, and is a Lifetime Certified Professional Broadcast Engineer. He has held the title of Chief Engineer and Group Director of Engineering for stations in Spartanburg, SC, Raleigh, NC and Cincinnati, Ohio, and holds Amateur Radio call W8GEL.
As HD radio approaches 15 years since its initial rollout (2002), it is worth taking a look back at where it’s been and a look forward on where it’s going. The HD Radio of today bears little resemblance to what was introduced in 2002, with respect to transmitter hardware, receivers, and features.
On the transmission side, it’s interesting to recall that the first exciters, costing upwards of $30K, were largely Linux based PC’s with modulation and upconversion cards mounted in the expansion slots. Implementation involved either costly and lossy combining schemes or drastic sacrifices to transmitter efficiency. And what came out of the antenna was a hybrid signal at only -20 dBc with questionable coverage parity with its analog component. Receivers were non-existent, and it was promoted purely as an audio quality improvement of a single channel. It had a data component, but no one really knew what the “magic app” for that capacity might eventually be.
By 2005, a movement to use excess bandwidth capacity for multicasting was heavily promoted mainly by NPR affiliated stations. It was implemented with the introduction of the Importer and Exporter components, but hardware costs remained high until the introduction of the “embedded” Exporter in 2008 from all manufacturers. NAB played a role in the project in an effort to lower the cost of conversion through an introductory discount. On the receiver side, there was an initial surge in available home and tabletop HD receivers capable of multicast reception, automotive receivers were limited to aftermarket add-ons.
Hybrid transmitters (no external combining) became more common and the 20 kW barrier to solid state HD Radio was broken in 2009 with Nautel’s introduction of the NV40. In 2010, the NRSC proposed, and the FCC adopted, rules permitting up to -10 dBc digital injection, finally enabling digital coverage comparable to analog. Auto manufacturers began offering HD Radio at least as an option, and in a few cases, as standard equipment.
Fast forwarding to today, there are close to 40 million HD Radio automotive receivers in use, compared with only about 1.1M in 2008. Stations operating with HD radio have more than doubled since 2008 from about 1,100 to over 2,500. Counting multicast channels, that’s over 4,000 streams. Most HD Radio implementations today use hybrid (analog + digital) transmitters, with vastly improved efficiency and reliability. With Nautel’s recent introduction of Multicast+, conversion hardware cost today can be as little as $15K. Infotainment systems in the “connected car” have opened the door to a station using HD Radio metadata to “billboard” itself and its content beyond just audio (Radio with pictures!). That parallels what Sirius-XM and online streaming can display.
So where does HD Radio go next? NextRadio has been chipping away at cell phone integration of FM receivers, but so far it has been largely analog. The next frontier for FM HD Radio may be to include it in cell phones. Improved power consumption on HD Radio decoders for portables will make this a reality.