Hidden stations on the North American FM dial

Recently I purchased a second-hand, portable, AM/FM radio. I paid more than you'd expect for it, around $50 USD, because this model (the Sangean HDR-14 from 2018) is one of very few standalone consumer radio receivers on the market that can decode HD Radio signals. It's a decent radio, but this isn't an equipment review. What I want to talk about is the HD Radio standard itself.

Digital radio: radio, but digital

Like its analog counterpart, digital radio provides unencrypted signals you can receive anywhere within antenna range as long as you have the right equipment, no telecommunications provider subscription required. But it comes with the added advantage of signal redundancy and audio clarity; under conditions that would muddy the sound of an analog signal with static and interference, you can still get a digital signal that exactly replicates what is being broadcast from the station. The Digital Audio Broadcasting (DAB or DAB+) standard is used in Europe and to a more limited extent elsewhere to provide digital radio broadcasts on specially allocated frequency bands. Some stations in Europe have even switched off their analog FM broadcasts in favor of DAB+ only. Another standard, Digital Radio Mondiale (DRM), is used for some far-reaching shortwave news broadcasts. For regulatory reasons I don't understand, Digital Audio Broadcasting is not presently used at all in North America, and Digital Radio Mondiale is only used here in the shortwave band, not in the medium wave band most radio receivers support for receiving AM broadcasts.

A portable radio receiver featuring the HD Radio trademark logo

HD Radio: the American way

The only form of public digital audio currently broadcast over the air in Canada, the US, and Mexico is called HD Radio. HD Radio is a proprietary standard that equipment manufacturers license from iBiquity Digital Corporation, which kinda bugs me because I suspect that might contribute to the relative scarcity of HD Radio receivers on the market, which contributes to slow consumer adoption, which in turn disincentivizes manufacturers from licensing more HD Radio receivers in a vicious cycle. But I'm no economist, and maybe someone who knows more about the market could produce contrary evidence.

The major feature that differentiates HD Radio from DAB, DAB+, and DRM is its implementation of in-band on-channel (IBOC) broadcasting. This means that unlike a DAB/DAB+ signal broadcast in a frequency band reserved for that standard, or a DRM signal broadcast in shortwave band without any analog component, HD Radio digital signals are broadcast on frequencies directly adjacent to an analog signal and carry the same audio stream simultaneously. The in-band on-channel model is aided by the greater bandwidth available to FM broadcasts in International Telecommunication Union Region 2, where they are centered on frequencies 200 kHz apart, unlike in other parts of the world including Europe that use an FM band spacing of 100 kHz. It makes the introduction more transparent to the listener, who only needs to tune to the same old FM frequencies they're used to and let the HD Radio decoder produce a static-free audio stream from the digital signal that a digitally-tuned analog receiver would essentially ignore. If the digital signal momentarily drops out, the radio can temporarily and almost seamlessly fall back to the adjacent analog signal. For the most part, listeners discover HD Radio because they're driving one of the recent-model cars that are equipped with an HD Radio receiver—though manufacturers are not mandated in any way to implement one. The IBOC model allows these listeners to experience digital radio without seeking it out or doing anything new.

Secret gay radio

For free, broadcasters get a license to add an HD Radio transmission that provides a synchronized duplication of the analog broadcast. These broadcasts are identified by the call sign of the analogue broadcast suffixed with “HD1.” It's HD1 because, depending on factors like the digital bitrate used for the lossily compressed audio stream, there could be as many as four digital transmissions flanking an analog FM broadcast. HD1 is, by regulatory fiat, always the same audio stream as the analog signal. But the other, additional digital signals could be anything else that can be lastly broadcast on FM radio. Often these are used to simulcast or repeat a station from another geographical area, or the programming of an AM talk radio station owned by the same broadcast licensees, but sometimes they carry stations that are not broadcast as analog over-the-air signals anywhere. Since most listeners still don't have HD Radio receivers, these digital-only stations feel almost secret.

Two such stations I can receive here are dedicated LGBTQ-focused music and news programming: Channel Q, broadcast locally on WZMX-HD2, and Pride Radio on WKSS-HD2. Both are syndicated nationally across the US, but only as these extra digital signals. They're not really secret, because both are available for internet streaming, but an analog radio listener wouldn't find either of them on the dial. Both of them play a lot of fun, dancy music; this is where I first heard “Unholy” by Sam Smith and Kim Petras.

If I told you I'd been listening to “secret gay radio” you might reasonably imagine this as a sort of underground cultural project of the LGBTQ community, maybe a pirate radio program broadcast from a network of unlicensed shortwave stations. But the reality of it is much less enchanting. Channel Q is produced by the second-largest radio company in the US: Audacy, Inc. Pride Radio is run by iHeartMedia—the largest US radio company. Both Audacy and iHeartMedia run a mix of mostly music FM stations and mostly “news talk” AM stations.

Something you have to understand when discussing the news talk radio programming format in the United States is that it is almost exclusively the domain of what passes for “conservative” media punditry here, which has veered ever further into ultra-reactionary provocation, as chronicled recently on The Divided Dial.

An iHeartMedia-owned network syndicated Rush Limbaugh's show until he died in 2021. Limbaugh is widely credited with creating the conservative news talk format as we now know it: essentially a few hours at a time of riffing on the news, taking phone calls from listeners whom he would compliment or denigrate as he pleased, and mocking anyone and anything he could associate with his political opponents. Emblematic of his style was a recurring “AIDS update” segment that ran in his show during the height of the HIV/AIDS crisis in the United States, in which he would share the latest news of people contacting HIV and dying of AIDS-related illness over a background of music selected for lyrics he found to provide comical double-entendres about gay men. This was perhaps one of the last things in his life he was ever forced to apologize for, after ACT UP essentially bullied him into discontinuing the segment and making a token donation to a children's AIDS charity. He would continue to mock the personal tragedies of anyone he could paint as a clueless liberal.

Audacy has its own roster of conservative news talk stars. I recently tuned into their local WTIC AM news talk affiliate out of curiosity and tuned in just in time to hear host Dana Loesch a deliver a prolonged, mocking complaint about the “woke” World Health Organization ditching the word monkeypox in favor of mpox. She even artfully worked in a transmisogynist joke, comparing what she considered the delusion of the WHO attempting to destigmatize a viral disease she pretty explicitly associated with gay men to woke libs insisting that trans women are real.

It's exactly these same two companies that run the secret gay radio stations I can pick up on HD Radio. But that's consistent with the way they've done business all along. The deeply anti-LGBTQ news talk programming and the fun gay club music both generate advertising revenues, and from a corporate perspective they are not in conflict with each other. They simply run on separate stations targeted to separate audiences. The news talk stations have a large enough audience to make dedicated local analog stations profitable, while Channel Q and Pride Radio generate less profit, but still enough to find a national radio program repeated on these extra digital broadcasting slots across the country. It's cynical culture war profiteering. “Unholy” really slaps, though.

What it actually sounds like

The rural Connecticut town where I live is not the best place to receive certain local stations; a lot of those broadcasts are targeted to larger population centers surrounding us at various distances. For example, the regional National Public Radio news station, WNPR, comes in a little spotty, and if I drive a short distance west for any reason I need to tune in to a different NPR affiliate.

Given what I've said about the signal redundancy and improved signal resiliency of digital radio, I hoped the digital signals might prove more reliable than analog. In practice, it hasn't quite worked out that way. In some cases, though I can consistently hear the analog broadcast more or less clearly, with just a hint of static, I struggle to pick up enough digital signal for the radio to build the audio buffer it needs to switch from analog sound to digital.

For one thing, the digital signals are sometimes broadcast from a different physical location than the principle, analog signal. But what I hadn't really banked on was that regulations require that HD Radio digital signals be broadcast at a much lower wattage than their analog counterparts, to the point that they sometimes don't really carry as far as the analog signals. My understanding is that this might be a compromise around in-band on-channel broadcasting to prevent these digital signals from causing audible interference to analog reception. Or maybe it's that digital signals powerful enough to carry beyond the reach of analog counterparts on the same center frequency would wreak havock upon the delicate system of frequency allocations intended to prevent the geographic overlap of disparate broadcasts on the same frequency. But it makes me a little sad for what we miss out on by not having a dedicated DAB+ band; perhaps with that kind of signal resiliency at broadcast power on par with analog, more broadcasts could cover these sorts of gaps between major population centers, like where I live.

When the digital signals actually do come in consistently, I'd say they sound pretty good. I'm not an audiophile, but I think occasionally I notice certain subtle artifacts or qualities associated with lossy audio compression, similar to MP3s encoded at a slightly less-than-ideal bitrate. Cymbal crashes that sound just slightly off, in a barely perceptible way, for example. This effect is much less noticeable on some of the digital broadcasts than on others, and I suspect on the whole it's a bigger problem wherever the broadcaster had tried to fit a whole four digital signals into the sidebands of a single analogue channel. There are certainly some broadcasts where I can sometimes forget that compression is there. But even at its most noticable I find it preferable to the waves of static and interference I get on most of the analog broadcasts I can receive here.

You'll notice I haven't talked much about HD Radio in the AM band. That's because I haven't managed to listen to it yet; I can't seem to pick up a single AM broadcast augmented by HD Radio at home, though I've found some local AM stations repeated as additional HD Radio subchannels on an FM broadcast. I gather that at one point I might have been able to receive a number of HD Radio signals on the AM band, but now most of those broadcasts have been discontinued. The spacing of AM broadcast center frequencies is narrower and the HD Radio broadcasts in that band were therefore encouraged at lower bitrates than their FM band counterparts, producing lower-quality audio. But AM stations are more likely to carry news talk programming where high-fidelity audio is less important. I suspect what really drove AM broadcasters away from HD Radio in their band is that the relatively low power allowed in HD Radio broadcasting, combined with the requirement for listeners to use one of the relatively expensive minority of radio models that can decode HD Radio signals, put the standard at odds with the audience these broadcasters target. AM signals tend to carry farther than FM and can therefore cover rural areas more effectively. The rural listenership of AM stations are likely to be too far from the broadcast antenna to pick up the weaker HD Radio signals, and perhaps less likely to seek out more expensive HD-capable receivers that might not pick up any digital signals where they live anyway.

Wither the HD Radio revolution?

The Federal Communications Commission of the United States, which as a practical matter also effectively sets broadcast regulations for Canada and Mexico, selected HD Radio as an official digital radio standard in 2002. Now, 21 years later, I think I'm pretty much the only person I know who listens to it, while plenty of people I know are still listening to analog radio, if only in their cars. So, what gives? Is HD Radio a failed media format?

I've already outlined my thinly substantiated theory that the proprietary nature of the HD Radio standard locks manufacturers and radio listeners into a vicious cycle of scarce equipment and slow consumer adoption. But I suspect that problem is compounded by a marketing weakness of the in-band on-channel model. Consider that a DAB+ receiver has access to a whole other frequency band that an analog-only AM/FM radio does not receive. This makes it very obvious to someone shopping for a receiver that DAB+ models will allow them to listen to receive signals they can't get with analog models, and perhaps even entire stations they can't receive on an analog radio where they live. HD Radio also allows listeners to listen to stations they can't get on analog, but that feature isn't nearly as obvious up front. An HD Radio receiver does not feature a new, special, digital frequency band. It just tunes into the same frequencies the analog models do—only, with an HD Radio model those frequencies can carry extra audio streams you wouldn't otherwise get. But that's not obvious just from looking at the receiver controls. So consumer adoption continues to be driven largely by listeners accidentally buying into HD Radio when they happen to purchase a new car that has a capable receiver. And a lot of people aren't buying new cars in this market.

But despite the near-total abandonment of HD Radio on the AM dial, FM broadcasters don't seem in a hurry to ditch the idea. So I think HD Radio will not fizzle out now, but continue to grow at a snail's pace for years to come.

Digital radio is not internet radio

Radio is an interesting medium to me because of the lack of moderation between broadcaster and listener. Connecting to the Internet, for example, requires more than just a computer; it's a process gatekept to some degree by internet service providers, who can passively collect precise information about your individual network history—what servers you connected to, when, and typically what URLs you were requesting, too, as these are still not consistently encrypted. Those ISPs also have to contend with government agencies who can request or demand that they censor certain content or report on certain activities. By contrast, radio has higher barriers of entry for public speech (because not everyone can access high-powered broadcasting equipment or get regulatory approval to use it) but also provides for totally anonymous listening; broadcasters and governments don't just passively collect records of what stations you've been tuning into; advertisers have had to rely on consumer surveys and the like to estimate audience sizes.

Internet audio streaming—internet radio, personalized music streaming services, podcasts, etc.—has come to dominate audio media consumption for a lot of us. But it doesn't entirely replace over-the-air radio, and not only for the complicated reasons I just described, having to do with the role of ISPs in internet access. The fact is that there are still enough people who want to be able to just flip a switch, wherever they are, and hear whatever their local DJ is doing, to sustain radio as a medium.

As long as radio is going to be around, HD Radio is a huge improvement to the listening experience it can offer. But it is also an improvement frustratingly limited in its impact by regulatory decisions and its surprisingly difficult consumer adoption model. And it can do nothing to touch the deeper, less technical problems of the radio landscape in the United States: corporate consolidation, rampant hate speech, and the far-right project to build a more reactionary cultural hegemony.

Where not otherwise noted, the content of this blog is written by Dominique Cyprès and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.