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Amplitude Modulation

I recently purchased a Sangean HDR-141 compact HD Radio receiver after the local station that broadcasts baseball decided to move their AM/MW2 station (and most of their FM stations) exclusively to digital HD Radio broadcasts. In their announcement, they established that the time was right now that 20% of their audience was equipped to listen. That’s… an astonishingly low percentage, especially given that the technology was approved as the U.S. digital radio broadcast format over fifteen years ago. I, myself, was able to find one acquaintance capable of receiving HD Radio (in their car), and this receiver only handled FM.

Adoption has seemingly been low in the other direction as well. Though the airwaves near me seem flooded with broadcasts, the only HD Radio content is coming from the aforementioned station. Part of this is almost certainly because the standard itself is patent-encumbered bullshit from iBiquity3 instead of an open standard. Transmitting requires not only the encoder, but licensing fees directly to iBiquity. The public-facing language is very vague on the HD Radio website, but receivers also need to license the tech and I imagine if this was free they’d make a point of it (and there’d be more than three portable HD Radio receivers on the market).

It’s ludicrous to me that one company gets to bank off of having a proprietary standard accepted by the government. This would be bad enough on FM, but it’s downright heartbreaking on MW. Radio, especially AM, belongs to the realm of tinkerers. It’s about the most open form of distant communication beyond shouting from a mountain. By its very nature, a receiver can be built from a tiny handful of parts, and it won’t even require power. HD Radio on MW changes all of this. I can’t build a receiver without a power source, a licensed decoder, and a DAC at the very least. On top of that, MW HD Radio transmissions require additional bandwidth, and partially overlap with neighboring frequencies, polluting the airwaves. All of this for what? What iBiquity describes as ‘FM quality sound’. We have an existing technology for that: analog FM radio.

There’s an argument that broadcast radio usage is on the decline, particularly MW. I can’t see how HD Radio is going to do anything to remedy this; though I believe opening up the airwaves would. Most MW radio has historically been talk-based, which does not need anything approaching high fidelity. If there’s a concern over music stations running out of bands on FM, that actually is solved by HD Radio with the advent of multicasting. And again, while I don’t love the idea of FM going digital, I’d prefer a bunch of multicast nonsense in that band over MW losing its essence. And when I have DXing radios3 that pull in MW from 400 miles up the coast and SW from China, I’d definitely prefer that stations spouting digital noise that interferes with neighboring frequencies stay out of the MW spectrum.

I suppose I’m bitter about this whole thing because I didn’t see it coming. As mentioned, iBiquity’s proprietary format was approved for U.S. broadcasting in 2002, and anecdotal evidence suggests it hasn’t really taken off. Even in markets where it has seen adoption, I’ve fortunately mostly seen it on FM. For the intellectual-property-burdened, license-waving capitalists at iBiquity, I’m sure it makes perfect sense. For consumers, for radio enthusiasts, for believers in open communication… it’s not only a travesty, it’s entirely illogical. Nobody listening to MW has ever expected CD-quality transmissions – that just isn’t the point. I would imagine iBiquity’s adoption boasts are what they are not because consumers give a shit, but because their car has an HD Radio receiver and the FM station they already knew happened to start a simulcast. Coincidental consumption is not a great metric.

I hope this experiment fails for my local station. I hope FCC licensing is opened up to remove the burden for amateur broadcasters on MW, if there’s any genuine concern out there about the airwaves falling out of favor. If iBiquity wants to leach money from the air, let them leach it from FM. Free and open AM is too precious.


  1. I may review the radio later, but so far my take is that the UI is poor compared to the C. Crane Pocket I used in the bed/bath before, but reception is very strong. It seems sensitive to placement, though, easily wiped out by nearby electronics. The quality of HD Radio is so unimportant, but the noise floor is noticeably silent which may be appreciated. RDS is certainly nicer than Shazaming everything. ↩︎
  2. For folks who aren’t radio nerds, AM (Amplitude Modulation) is the manner in which the signal is broadcast, whereas MW (Medium Wave) is the band of frequencies typically associated with ‘AM Radio’. Since amateur/shortwave transmissions also use AM, this is a distinction I will be making throughout this post. I won’t be discussing FM (Frequency Modulation) enough to need to distinguish technology from band. ↩︎
  3. iBiquity was a merger of USA Digital Radio and Lucent Digital Radio, now owned by DTS (a brand of Xperi). I don’t want to link to any of their sites, though it’s tempting because they’re so comically shit. Completely transparent buzzword-laden marketing nonsense and intellectual property wankery. ↩︎