The definition of “radio” just got more complicated. Walk into any big-box electronics store and ask for “digital radio,” and they’ll (more likely than not) point you to XM and Sirius satellite receivers – much to the consternation of terrestrial radio broadcasters, who want their “HD” technology to be synonymous with “digital.” Receiver manufacturers are also blurring this boundary – one will soon roll out a receiver which is both XM and HD-compatible.
Now, XM has 
filed for a patent on the process of taking an XM satellite radio signal and rebroadcasting it as one of the channels on an HD-equipped FM radio station. This is actually somewhat easier than it might sound, because the audio encoding algorithms used by HD radio and satellite radio are related – they’re products of Lucent Technologies. Lucent has not only licensed its codec technology to XM and Sirius, but it’s a partial-owner of iBiquity Corporation, the company that owns the HD radio technology.
In fact, during HD’s development, Lucent foisted the codec it licenses for satellite use onto the iBiquity platform, so as to force such lucrative cross-compatibility. But it degraded the audio (on AM broadcasts especially) to an unacceptable degree, which led Lucent to develop a variant of its codec specifically for AM/FM digital broadcasting.
It’s typically easier to convert between two related encoding algorithms than it is to convert between two that are unrelated. You are much less likely to lose data in the conversion process as well. The maximum bitrates of satellite signals is not much more than what’s capable on an HD-enabled FM station.
As an added bonus, since Lucent is involved in the proprietary technology on both ends of the process, XM might not have to pay heftily to engender this sort of compatibility.
Major radio broadcasters, who are the primary investors in iBiquity, win twice. They’re given access to an incredible array of content to carry on their new multi-channel digital signals, which are otherwise not much to write home about. More importantly, one of the radio industry’s two largest competitive threats now holds potential as a revenue stream. XM wins by exposing a larger audience to its wares; though an HD side-channel can (at this point) only carry one satellite channel, perhaps the taste may entice new subscriptions to XM’s full 170-channel spread.
Then again, why restrict satellite to secondary status on the AM or FM bands? Imagine a strategic alliance between XM and Clear Channel. Perhaps a stock-swap, or something, whereby Clear Channel becomes a holding company for stations that are wholly programmed by XM, and receives a cut of all subscriptions generated via over-the-air listening. If a single FM station can broadcast up to four digital program streams, and a single company can own eight stations in a market, there’s a lot of potential to bring much satellite programming down to earth. Implications worth considering.
Skip to content