When HD Radio was under development and policy-discussions on the technology were in their infancy, proponents of the system bragged about all of the game-changing features it would have. This included audio quality that sounded better than CD and the ability to broadcast a plethora of digital data beyond audio itself.
They also told us that digital radio signals would be more robust and easier to receive than their analog counterparts. This was a critical assertion, because HD Radio works by shoehorning digital signals onto the existing AM and FM bands, right next to analog ones, and thus to avoid interference the HD signal can only be broadcast at just a fraction of a station’s analog power output. But proponents said that was okay: HD Radio only needed a fraction of the power to kick ass and blow minds.
Then came reality. Broadcasting at just 1% of a station’s analog power, HD Radio signals can be difficult to receive. Not only can they drop in and out when you’re on the move, but HD signals have a hard time penetrating some buildings. These problems are especially noticeable on the FM band.
Starting in the mid-2000s, HD Radio proponents embarked on a quest to build the case for increasing the broadcast power of FM-HD signals from 1% to 10% of analog power. The process was quite controversial, with public radio broadcasters very concerned that increased digital power would cause increased interference between stations, while commercial broadcasters said it would be no big deal.
After months of slagging each other, National Public Radio and HD Radio’s commercial-broadcast backers came to a back-room compromise on an FM-HD power hike, and in 2010 the FCC approved it. FM-HD stations could raise their digital power to anywhere between 4% and 10% of their analog output. The FCC also implemented rules that made it nearly impossible for a broadcaster or listener to lodge complaints about any increased HD-related interference between stations.
Generally speaking, these slightly beefier signals are somewhat easier to lock and listen to, and they are somewhat more receivable in buildings. However, very few stations have actually applied for and implemented any digital power increase, which the FCC calls "disappointing." Additionally, increasing FM-HD power has indeed led to actual increased interference between stations—the FCC may be in denial, but examples abound on YouTube.
What do you do if your controversial solution to fix a design flaw in FM-HD doesn’t work? Apparently, you double down.
In June, Clear Channel senior operations engineer Alan Jurison published a white paper about increasing FM-HD power, designed to "add to the technical record the tangible benefits of elevated digital power." After mouthing the standard industry-lines about the technology (HD is great, it has traction in the marketplace, and increasing FM-HD power has been painless and fruitful), Jurison provides a report on some listening-tests he’s conducted on Clear Channel FM-HD stations in New York and Los Angeles.
In a nutshell, Jurison drove the major highways of the metropolitan areas with reception and logging equipment and compared FM-HD signal robustness at 1% of analog power and 4% of analog power. No real surprise that increased power leads to better digital reception—but it still falls short on many stretches of roads, especially in the more affluent suburbs of New Jersey and Connecticut.
In the LA metro, the terrain and density of stations on the FM dial means that most are limited to running at the minimum FM-HD power (1% of analog). But no two radio stations are exactly alike, so there’s some variation in the amount of digital wattage Clear Channel’s stations can put out. For example, both KBIG-FM and KIIS-FM are, in FCC parlance, "Class B" stations that run their FM-HD signals at 1% of analog output. But KBIG is licensed to broadcast with more power, and thus can broadcast a stronger FM-HD signal (650 watts) than KIIS (80 watts).
Again, no surprise that it’s easier to receive KBIG’s digital signal than KIIS’, but the area’s terrain exacerbates reception challenges for both stations. This problem is inherent to HD Radio’s design, and reflects an early-held (and wrongheaded) belief that just because a signal is digital, it will outperform analog.
Jurison lays some blame for this at the feet of auto manufacturers, who have sacrificed antenna functionality for vehicle design aesthetics. Over the last two decades, stock radio antennas in automobiles have morphed from external whips mounted on the front of the vehicle to little nubs that can be located anywhere. In many newer cars, the antenna is now a small wire often buried in the rear window. Result: radio reception has been degraded in the car, and this is especially noticeable with digital radio.
The primary takeaway of Jurison’s paper is that the 2010 FM-HD power hike from 1% to 4% of analog power has not been a meaningful solution to HD’s listenability problems, "almost always fall[ing] short in replicating a station’s analog coverage." Considering that radio faces increased competition in a networked world, this is an existential threat, and something must be done:
Many complaints are logged by people regarding the underperformance of their digital radios. Those complaints and the dissatisfaction of listeners will only increase as millions of additional digital radios are sold each year. If current trends continue, by the end of the decade, digital radios will reach critical mass. I feel the industry is woefully underprepared for how inadequate [4% FM-HD power] coverage can be.
Jurison then suggests that the industry work to renew research in broadcasting FM-HD signals at 10% of analog power. The FCC’s digital radio rules limit many stations from adopting the full FM-HD power increase, in order to reduce the chances of interfering with their neighbors on the dial, especially in crowded markets. But Jurison says these concerns are overblown, and points to the lack of official complaints about FM-HD interference.
"Why should we hold back and harm the entire industry from having a successful digital transition based on concerns that still, to this date, have not materialized?," he writes. "Let us ensure there are safeguards in place to mitigate any interference on a case-by-case basis." But "the time has come" to push for a full-on, broad-spectrum 10% FM-HD power level for all stations.
Of course, Jurison ignores the fact that the FCC’s rules set the bar so high for making a complaint about digital radio interference that you really can’t file one—the regulatory equivalent of plugging your ears and singing "la la la I can’t hear you." This, too, was done by design. It’s not an honest rationale.
I expect we’ll see increased presentations on this subject at industry conferences, including the annual NAB Radio Show in September, and in the broadcast engineering trades over the next year. Clear Channel will work with iBiquity and the National Association of Broadcasters to produce the necessary "science" to justify the change, and a plethora of broadcast-investors in HD Radio will endorse the results without qualification. Then it’s on to the FCC to press for a blanket 10% FM-HD power increase (at a minimum), with little oversight or recourse.
Although other avenues exist to improve FM-HD reception without dramatically raising broadcast power, it appears HD proponents prefer the brute-force option.
The interesting thing to watch will be whether the industry splits again over the idea. The driving force behind NPR Labs, public radio’s primary HD innovator, has since retired, his replacement was just canned, and financing and oversight of the Labs have been folded into NPR’s Technology and Operations division. Thus there will likely be fewer thoughtfully critical voices engaged in these future projects and policymaking. More’s the pity.