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Radio AM to FM: January 9, 2004

Static in the Air

If your AM radio sounds a bit strange lately, it may be due to legal interference: in early December, KTNQ (1020 AM) started broadcasting so-called HD Radio, or "In-band, On-Channel" digital, which places a digital signal alongside and just under the main analog carrier.

The idea is to improve the sound of AM broadcasts though the use of digital technology. And it sounds great ... on paper. In reality, while some like the new digital sound, others feel that HD Radio in its current incarnation tends to sound artificial.
But then there's "the hash."

Tune into 1020 AM with a typical AM radio, and you probably won't hear much difference between it and other stations. It does sound a little duller on some radios due to the fact that for IBOC to work, the audio bandwidth -- the frequency response of the station -- must be limited to either 5 or 6 KHz, compared with 10 KHz or higher under current regulations.

Tune into 1010 or 1030 AM, however and you'll hear the digital sidebands, a sort of hiss that sounds somewhat like tuning between FM stations. The difference here is that if there were a far away station you liked, with FM on a clear day you'd still hear it. With IBOC, the hiss actually covers the weaker signal completely. As far as I know, there are no stations that can be heard on 1010 or 1030 in Los Angeles when IBOC broadcasts are authorized: the daylight hours.

Now tune into 1000 or 1040. There ARE stations there. When IBOC is running on KTNQ, there is a ringing sound that covers the distant signals. You can still hear them, but you wouldn't want to listen long.

It's not KTNQ's fault. From what I have learned about the situation, the antenna system was professionally tuned for IBOC, the system was inspected by one of the nation's best radio engineers, and the studio is state-of-the-art, sending a fully-digital signal to the transmitters.

The fault, if you want to call it that, is the IBOC system itself, which puts digital energy into the sidebands of the station. If many more stations adopt it, they could theoretically cancel each other out.

Of course many AM radios are so bad, with such limited bandwidth, that many observers think it doesn't matter. Get digital radios into the hands of consumers, and then it will be different: then AM will be on par with FM. When enough HD tuners are out, turn off the analog signal for good, similar to what is expected with high-definition television in 2007.

But wait, says the other side: analog on a good radio sounds much better than digital, and good analog AM can actually sound as good as FM, they say. One AM engineer I spoke with says that his station won't use IBOC until people demand stations that sound like bad internet streams.

Personally, I don't know. I know how good AM can sound, but I also know how bad it sounds on most current radios. I know that many people think it is the station, rather than the radio that makes AM sound so bad. Yet I don't know if people will demand better radios if the same lame programming occupies most of the band, I don't know if people will like the way IBOC radios switch between analog and digital abruptly, and I don't know if people will pay big money for new receivers when they are already leaving traditional radio completely for other entertainment sources such as MP3 players, satellite subscription radio and compact discs.

At least with KTNQ on the air with HD, we can finally evaluate it. Soon, anyway, since Kenwood is beginning the rollout of HD Radio tuners (retail $500) that can be added to a Kenwood HD-ready car stereo. They are currently available in Cedar Rapids, Iowa, and they will be coming to a Southern California sometime in early 2004, according to the company.

KTNQ has taken a bold step, and will soon be followed by KNX (1070 AM). Between the two, we may be hearing the future of radio. Or we may be witnessing nothing more than an expensive experiment.

And then there's FM IBOC ... to be continued ...


Copyright © 2004 Richard Wagoner and The Copley Press.

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