This begins HD Radio’s 13th year as the de facto U.S. digtital radio standard. With a broadcast penetration rate still hovering at around 15 percent and listener uptake at a third of that, there’s still a long road ahead before the technology reaches any semblance of marketplace criticality. That said, HD proponents have many narrative threads in play, all of which will bear watching in the coming 12 months.

The Coattails Effect. Broadcasters have demurred investing in HD transmission technology until listeners have receivers. By and large, they still don’t, but HD proponents are hanging their hopes on two primary vectors: the car and the phone.

According to iBiquity, nearly half of all new cars sold in the U.S. have an HD receiver onboard, but there’s no way to verify this claim. Realistically, just because an automobile has HD reception capability doesn’t mean it gets used, and following listener complaints some models now provide the option to disable HD reception. With listening attention continuing to splinter in the dashboard, HD Radio is playing catch-up ball.

However, iBiquity’s strategic alliance with Emmis Communications’ NextRadio app stands to raise HD Radio’s profile. NextRadio is the closest thing the broadcast industry has to offering a uniformity of listening experience across digital devices. Coupled with NextRadio’s partnership with RadioDNS, broadcasters now have the potential for a platform that may allow for seamless switching between over-the-air and streaming signals (provided broadcasters can be convinced that such functionality is desirable). NextRadio has also made more headway into the dashboard, and on mobile phones, in the last two years than HD Radio has in the last decade.

From the app’s perspective, the HD signal is just another data stream that adds relatively minor overall functionality, so no harm done having it along for the ride. But can NextRadio alone turn the adoptive tide for digital radio more broadly? Opinions differ on the meaningfulness of its uptake, and so long as U.S. wireless carriers continue to resist installing/enabling FM chips in their phones, this will be an elusive market at best. In this alliance, HD Radio is without a doubt poised to ride NextRadio’s coattalis, but it remains to be seen if the app’s even sporting a jacket yet.

AM Tech. 2014 was a busy year for broadcasters experimenting with the all-digital variant of AM-HD broadcasting. Major findings: digital sounds better than analog, but reception is still compromised at night and by many of the usual suspects that mangle analog AM listenability. Going all-digtital might be an improvement for, say, 15% of existing AM broadcasters, but many stations won’t be able to make the upgrade, for financial or technical reasons.

A principal in the all-digital tests thinks the future of AM is on FM—but if broadcasters are serious about maintaining some semblance of relevancy on the AM dial it may very well require mandates on both broadcasters and listeners to force a digital transition. A non-starter in the current political climate, but policy debates have to start somewhere, and staking out a radical position leaves plenty of room for “compromise” down the road.

FM Tech. Clear Channel iHeartMedia’s been running the numbers to see if there’s any headroom to allow a blanket 10-fold power increase for FM-HD radio signals. It’s important to remember that broadcasters agreed to a four-fold increase five years ago , but only after contentious debate and out of caution to the fringe signals of analog neighbors to a beefed-up FM-HD station.

In approving the compromise, the FCC left open the door for FM-HD stations to increase their digital power by 10x, but only after showing that they would not cause interference to other stations. Then, it set the bar so high for determining what constituted interference that it effectively gave stations the green light to jack their power to the maximum extent they could.

Five years later and perhaps half of eligible FM-HD stations run with some degree of elevated sidebands. Considering that interference complaints are all but impossible to file, it’s no surprise that Clear Channel iHeartMedia is now advancing the notion that the FM-HD power hike was an unqualified success and even more power is necessary.

This is an excellent example of the compromise-by-design that HD Radio as a system represents. Cramming digital sidebands into already-crowded analog spectrum required the system’s designers to compromise on the power level of the digital signal. Congestion on the FM band has increased over the last dozen years, with the onslaught of FM translators primarily to blame. [The fact that HD Radio is in large part responsible for this onslaught has not helped matters.] Furthermore, although a third party claims to have technology that would significantly improve HD signal reception on the receiver side, iBiquity seems content to freeze them out of system development.

Whether or not FM-HD stations get another digital power increase will be (much like AM-HD) determined by just how much the FCC gives a sh*t about broadcast policymaking in the new year. The agency’s got many other policy projects teed up of infinitely higher importance, and is likely (as in the past) to be swayed by whatever broadcast constituency speaks the loudest and most coherently, facts or no. Within the HD policy realm, an FM-HD power increase is relatively small potatoes compared to the potential overhaul of the AM dial that all-digital broadcasting might portend. But of all the technical initiatives in play, it’s those on FM that will ultimately have a greater impact on radio over the long term.

Independent Variables. In addition to the major balls HD Radio proponents must juggle, there are some other issues on which they would like to see resolution. A patent troll’s lawsuits against iBiquity and several broadcasters remain outstanding, though consolidation is likely. The troll’s case is specious, but even the semblance of uncertainty surrounding the system cannot help but temper what little enthusiasm broadcasters have for HD Radio. Meanwhile, a key supplier of automotive electronics continues to protest iBiquity’s license-fee business model. Within the last year, some broadcasters have even publicly broached the notion of considering HD alternatives, such as Digital Radio Mondiale, for tandem adoption as a way to breathe new life into radio’s digital transition.

Like in previous years, there’s no breakout story on the horizon for HD Radio. Instead, there are many threads to track. Will any of them provide us with any glimpse into the system’s long-term end-state?