In today's New York Times, I wrote about the revolution already in progress for AM and FM radio: IBOC (in-band, on-channel) digital radio, known by its trademarked named HD Radio.

With IBOC, the analog signal is undisturbed and digital audio nestles in the protected side bands. It's a surprisingly huge phenomenon--among radio stations. At least 450 stations are already full-time HD Radio broadcasters, and possibly more than 600. The reason? Digital AM sounds good--remarkably good.

But the real excitement is in FM. With digital FM, stations can choose to multicast. Public radio is funding a huge HD Radio supplement so that its member stations could, for instance, have an all Spanish format or serve other niche audiences that they can't offer enough programming to as part of their regular schedule.

There's only a few tens of thousands of receivers out there, but the tabletop boxes are coming. I was told the chips that drive HD Radio cost $65 for the radio makers now, but the price should drop by 2/3rds when quantities pick up, and then we'll see $100 to $150 radios instead of $260 to $600 units.

Reader Comment: Bill Kirkpatrick @wisc.edu says:

"It's worth pointing out that HD radio came largely at the expense of low-powered FM radio. We could have had thousands more LPFM stations, but large broadcasters objected to these microstations being shoe-horned into the spectrum. Why? So that there would be more room for IBOC. Commercial broadcasters effectively double or triple their spectrum, and non-commercial community broadcasting gets shut out.

There's a great article in Social Policy that explains all this in detail. I can't find it on the web, so I have quoted a relevant excerpt below."

From INTERFERENCE AND THE PUBLIC SERVICE: THE HISTORY AND IMPACT OF LOW-POWER FM , By: Spinelli, Martin, Social Policy, Fall 2000, Vol. 31, Issue 1

While arguments about existing station placement and economics are relatively easy to grasp, perhaps the most significant stumbling block for LPFM is more complex. IBOC-DAB (in-band, on-channel digital audio broadcasting) is left out of reports of the LPFM fight as often for its politics as for its difficulty. One could be forgiven for thinking that digital radio, when it happens at some point in the distant future, will be in a different radio spectrum than the one currently used. But "in-band," in fact, means in the existing FM radio frequency band on the same radio channels or stations that we listen to today ("on-channel").

The way IBOC is being promoted and tested by large broadcasters represents a kind of giant squatters' rights movement on the FM band. The current IBOC configuration, described as "saddle-bagging," would have a station broadcast a digital signal in the side channels immediately to the left and to the right of its analog signal. If two-channel separation standards were to be maintained, there would be far less room for other stations like LPFMs. Of course, if LPFMs are shoehorned into the bandwidth before the establishment of IBOC, there will be much less room for IBOC. The NAB, in seeking to stop or slow LPFM by calling for more engineering tests or trial periods, would buy its members enough time to rush the IBOC proposal through the FCC and establish digital broadcasting saddle-bags.

It is not surprising that LPFM opponents would not give prominence to the DAB objection in their complaints against microbroadcasting. If the IBOC saddle-bag system is established, existing stations will be given, in effect, three times the bandwidth for which they paid, while the consuming public, which has not indicated its desires or needs, will have a technology foisted on it--especially if, as it is being currently tested in the Washington, DC, area, it will be simply another means for existing stations to replicate their analog signals.

Incidentally, the existing IBOC saddle-bag tests are showing no interference to the mother channel to which they are immediately adjacent; consequently, the NAB has called for a loosening of the clear channel requirements for IBOC. This is further evidence that interference is not a genuine issue. It can thus be argued that existing commercial broadcasters do not actually object to LPFM because such stations might interfere with any of their existing signals but because their imminent presence would lessen the space available for their future digital broadcasts.

I'm a former broadcast engineer who has followed IBOC. Several Seattle FM stations use IBOC and I can't tell any difference between the "Spread" of their signal and the spread of the "normal" Seattle FM stations. And because Seattle was an IBOC-FM test market, a lot of people with experienced ears have been listening closely for problems. Many broadcasters are voluntarily investing big dollars in IBOC-FM.

This is not true with IBOC in the AM band, where the digital signal generates sidebands that tend to cover up the stations on the two adjacent channels. The problem is so bad that IBOC-AM cannot be used at night and as far as I know, nobody but Clear Channel stations are rushing to IBOC-AM. And, of course, Clear Channel owns a piece of the IBOC business.

I have been told that IBOC was broadcasting's answer to a European direct digital system, they were opposed because that system gives all area broadcasters an equal voice - power and dial location no longer matter. This was poison to those who want to sell their radio stations for lots and lots of money.

posted by Xeni Jardin at 08:30:41 AM permalink | Other blogs' comments