HD Radio proponents ask for, and get, major digital power increase; First adjacents get minor protection

The Media Bureau has dramatically increased the power level for IBOC digital FM service (the service known in the marketplace as “HD Radio”). In so doing, the Bureau effectively dismissed, or at least minimized, serious interference concerns expressed by non-HD stations (particularly those operating on channels first adjacent to HD stations). While the increased HD power authorizations will still be subject to a complaint process which could theoretically reduce maximum power available in certain situations, that complaint process – at least at first glance – falls short of everything a victim of interference might have hoped for.

The Bureau has decided that “eligible stations” should be permitted to increase their digital power by 6 dB – meaning that their digital power can move – pretty much with no questions asked – from the current maximum ERP of 20 decibels below carrier (-20 dBc) to -14 dBc. Once the new rule becomes “effective”, eligible stations will be permitted to go to that -14 dBc limit without any prior approval, as long as they file a notification of the increase through CDBS within 10 days. While the revised power increase rule won’t technically be “effective” for some time, the Bureau, apparently eager to make the higher power available without the legalistic nicety of “effectiveness”, has announced that it will grant STAs in the meantime. (See below for more details on the STA process.) Stations “eligible” for this immediate upgrade are non-“super-powered” stations.

Read on for more details.


HD Radio represents the first – and, so far, the only – technology generally available to bring the radio broadcast industry into the digital world. And unlike digital television, HD Radio promises the Holy Grail-like property of IBOC – “in-band, on-channel” operation that would not require any major upheaval in channel allotments. Where DTV involved massive reassignments of channels (not to mention two-channel operations during the run-up to the final DTV transition), radio licensees can stay on their original channel and simply tack-on digital operation much like a standard subcarrier (SCA) service.

The technology was developed by private parties, who spent years trying to convince the Commission that their IBOC system would work. The FCC agreed in 2002, despite considerable skepticism voiced by folks who did not happen to have any direct pecuniary interest in marketing the HD Radio system. But again, HD Radio was and remains the only game on the table for digital radio broadcasting. So the Commission, recognizing the seemingly inexorable movement of all media away from analog and toward digital, had little choice: if the radio industry was to be goosed toward digital, it made sense to officially bless the only system to walk in the door promising digital service. The fact that that system happened to be IBOC obviously sweetened the pot.

The digital radio specs originally adopted by the FCC were designed by HD Radio’s proponents and cheerleaders, who assured the Commission that those specs would be sufficient to deliver a station’s digital service to everybody who could receive the station’s conventional analog signal. (In industry parlance, digital coverage would “replicate” analog coverage.) The crucial parameter was power: a station’s digital ERP was set at one percent of its analog ERP (i.e., 20 decibels below carrier, or -20 dBc).

Oops. It didn’t take long to realize that full replication wasn’t happening, especially in “mobile and indoor environments” (a universe which, frankly, seems pretty all-inclusive, since it appears to exclude only non-mobile outdoor environments). And thus began the drumbeat for more digital power.

HD Radio cheerleaders pushed for an increase from 1% to 10% of authorized power for all but some Class B FM stations that happened to be “super-powered”.   That would represent a ten-fold increase – by any measure a very substantial boost.  FYI: “Super-powered” stations are those with ERP that exceeds the maximum for their class, or with facilities which produce a reference contour greater than the pertinent maximum class contour distance. See Section 73.211 of the rules for more detail.

While Team HD Radio pushed hard for immediate, or near-immediate, action on their request, others – primarily National Public Radio – urged a more cautious approach. But last November, NPR and the HD Radio proponents reached agreement on increased power levels and the FCC has now largely signed onto the terms of that agreement.

New Power Limits, Complaint Process

As described above, non-super-powered stations will be able to increase their digital power by 6 dB on their own with no prior FCC approval (provided that they notify the Commission within 10 days). But there’s more. 

Eligible stations would be permitted to apply for even greater power increases, up to a total increase of 10 dB over current levels – i.e., to -10 dBc. Because of the Bureau’s concern about possible first adjacent interference, the maximum increase beyond the 6 dB automatic increase described above will be based on a “go/no go” analysis designed specifically to protect potentially affected first adjacents. The analysis is based on calculated field strengths; anyone thinking that such calculations fail to account for peculiarities – terrain, environmental or technical –which produce anomalous results are invited to demonstrate those factors in the application.

Super-powered stations of any class – not just Class B – will be limited to “the currently permitted -20 dBc level or 10 dB below the maximum analog power that would be authorized for the class of the super-powered FM station adjusted for the station’s [HAAT], predicted in accordance with Section 73.211(b).” And unlike their non-super-powered pals, super-powered stations will not be permitted to crank up their digital power with no prior FCC say-so. Rather, super-powered stations will have first to file an application, in the form of an informal request, for any increase in digital ERP. 

If you’re unsure of whether your station is “super-powered”, fear not: the Bureau has posted a jim-dandy gadget on the Audio Division’s webpage that determines whether any station is super-powered and, if so, calculates that station’s maximum HD power. You can try this tool – dubbed the “FM Super-Powered Maximum Digital ERP Calculator” (presumably, “super-powered” here is not intended to modify “calculator”, but you never know) – by going here and entering the station’s call sign and Facility ID Number.

While the Bureau’s decision clearly signals its interest in promoting digital radio, the decision nonetheless provides a formal complaint mechanism for first adjacents convinced that they are suffering as a result of a neighboring station’s digital power increase.    The complaint process is not, however, particularly user-friendly.

If a full power analog station (LPFMs and translators need not apply) believes that it is receiving interference within its protected contour from an HD station operating with digital ERP in excess of -14 dBc, the interferee must first attempt to “work cooperatively” with the interfering station to resolve the issue. That is done by progressively reducing the HD station’s digital operating power until a mutually agreeable power is reached.   If cooperation is successful, the HD Radio station must simply notify the Commission of its new digital power. 

If no amicable resolution is reached, the station receiving interference may file a complaint with the FCC. This is not a streamlined complaint process. Rather, the complaint must be supported by at least six reports of on-going (not transitory) interference. Each report must include a map showing the location of the reported interference and a detailed description of the nature and extent of the interference at that location. Interference allegedly occurring outside the station’s protected analog contour will not be considered. 

The Bureau is supposed to act on such complaints within 90 days. As a concession to the likelihood that the Bureau may have difficulty meeting that deadline, the new rules provide that an allegedly interfering station must, when the 90-day deadline is reached, reduce digital power to -14 dBc pending Bureau resolution of the complaint. If complaints continue, the Bureau may order further reductions – first to -17 dBc, later to -20 dBc – pending Bureau action on the complaint.

Such a mandatory reduction scheme may seem helpful to the suffering first adjacent complainant, but let’s think about that for a minute. The mandatory part kicks in only after: (a) the complainant has learned that its protected contour is getting beat up and has identified the apparent offender; and (b) the complainant has tried, unsuccessfully, to “work cooperatively” with the interfering HD station; and (c) the complainant has compiled the necessary showing (at least six on-going instances, mapped and documented); and (d) the complainant has filed its complaint; and (e) 90 days have then passed. If the complainant turns out to be correct, that means that it will have had to suffer months, possibly even a year or more, of harmful interference before getting any relief.

STAs available NOW!

It’s pretty clear from the decision that the Bureau really wants to give HD Radio Nation a big leg up. Further underscoring that is the fact that the Bureau is making the initial 6 dB power increase available to HD Radio licensees even before the new rules have become formally “effective”.

The effective date of the rules will occur as of the later of: (a) thirty (30) days after publication of the decision in the Federal Register; or (b) announcement in the Federal Register of OMB approval of the new rules. But that’s obviously too long to wait, so the Bureau has invited requests for STAs to increase power (by up to 6 dB). The Bureau has even posted a handy-dandy step-by-step instruction on how to file such a request, detailing precisely what information to include in it.

The bottom line here is that the Commission is clearly committed to the concept of digital radio . . . even though that service has been struggling for years, without much apparent success, to gain any kind of traction in the marketplace, and even though broadcasters themselves have been less than enthusiastic about it (at least judging from the dwindling number of stations seeking to take the HD plunge). Still, the Commission is doing its best to prop HD Radio up. That may be just what the doctor ordered, and it may turn out to be a huge boon to the radio industry generally. But if the digital power increase causes substantial interference to analog stations which still constitute the vast majority of the radio industry, that increase could turn out to be just one more unwanted and unneeded difficulty in an industry which is already dealing with a boatload of other difficulties. Time will tell.