HD Radio tech: Digital, clearer and possibly intrusive
*Mitch LeClair**
**St. Cloud Times**
**
**9:40 p.m. CST February 21, 2015
http://www.sctimes.com/story/news/local/2015/02/21/hd-radio-tech-digital-clearer-possibly-intrusive/23824417/
*
STC 0222 KASM Gone HD 6.jpg
*(Photo: Jason Wachter, [email protected]
<mailto:[email protected]>)*
HD Radio has existed for 13 years, and its development stretches back
decades.
Its name does not mean "high-definition," but its AM stations sound like
FM, and FM clarity is near CD quality.
*Read more:*HD Radio technology changes operations in Central Minnesota
<http://on.sctimes.com/1EhJhgg>
Like satellite signals, HD Radio broadcasts digitally using radio waves
but with different frequencies, said Yi Zheng, engineering professor at
St. Cloud State University.
"In-band on-channel," or IBOC: "That's what you're referring to when you
say HD Radio," according to Jim Gray, director of operations at KVSC-FM
in St. Cloud.
Digital signals are not "piggybacked" on but rather "slid into the same
space" as an analog signal, Gray said.
A main benefit of digital, he said, is that he can use advanced audio
processing to deliver high-quality talk and music despite low bitrates,
or the amount of data a station can transmit at one time.
One of the problems, Gray said, is interference, as digital signals on
either side of analog territory can bump into other stations' broadcasts.
Gray said KVSC keeps its power a bit lower than it could, as
interference potential exists with a Brainerd station at 88.3 Mhz (KVSC
sits at 88.1).
In 2010, the Federal Communications Commission gave stations the OK to
increase transmission power of digital signals, from 1 percent of total
analog energy to 10 percent.
The decision came after much contention, including some from Minnesota.
An engineer from Grand Rapids told the FCC in 2009 his analog FM station
had "experienced a reduction in coverage 20 to 30 miles of our signal
from HD (Radio) interference."
A study by iBiquity Digital Corp. — the company that developed and owns
proprietary technology behind HD Radio — revealed little concern about
interference, though one by National Public Radio differed.
In a report, NPR Labs said with a power increase, most in-home analog
radio listeners "will experience a significant reduction."
Nick Kereakos, chief technology officer at Minnesota Public Radio, said
much of the concern over the power increase turned out to be overblown.
Gary Hoppe of Tri-County Broadcasting echoed Kereakos and said his
stations, including WHMH-FM/Rockin' 101, have had no problems with
interference before or after adopting HD Radio technology.
Joseph D'Angelo, a vice president at iBiquity, said the FCC-approved
power increase in 2010 substantially increased HD Radio signals'
building penetration. He said 2014 also brought changes to the
technology, with artist experience (synchronized images delivered to
receivers) and emergency alert services emerging.
D'Angelo said the initial focus for the alerts is in Tornado Alley, with
a wider rollout planned in coming months.
Further in the future, Zheng said it's "very highly possible" all radio
signals and receivers could be digital.
Until then, educate yourself: Find more about HD Radio technology at
FCC.gov
<http://www.fcc.gov/encyclopedia/iboc-digital-radio-broadcasting-am-and-fm-radio-broadcast-stations>,
HDRadio.com <http://hdradio.com/>, NRSCstandards.org
<http://www.nrscstandards.org/> and DIYmedia.net
<http://diymedia.net/?s=hd+radio>, a site from a broadcast professor,
author and digital radio researcher.
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