All-Digital AM-HD Testing Planned

From the doubling-down department: the National Association of Broadcasters is recruiting candidates to test iBiquity Digital Corporation’s all-digital AM-HD Radio system.
So far, Beasley Broadcast Group has offered the use of one of its AM stations for the purposes of experimentation, and reportedly two other broadcast companies are also on board. When the tests will be conducted, and which specific stations will be involved, remains to be determined.
Proponents’ rationales for this experiment are curious. They believe that small to medium-market AM stations – many of which are in significant financial distress – may find economic salvation by going fully digital.
One small problem: small to medium-market AM stations have not invested in HD Radio technology over the last 10 years, precisely because they operate on slim-to-no margins. The primary drivers for the proliferation of HD have been the country’s largest broadcast conglomerates, who’ve invested in iBiquity and thus have a real stake in its success or failure.
(On the FM side, HD proliferation has trickled down into some smaller markets, but in a piecemeal fashion and without any real fanfare. In fact, the number of FM-HD stations may actually be on the decline.)
“Upgrading” any station for HD broadcasting also requires a significant up-front investment. In addition to the license fees iBiquity requires from broadcasters, many radio stations have to make significant improvements to their airchain in order to pass through the best-quality digital signal they can.
When all the costs are combined, a radio station will spend anywhere between $50-250,000 just to implement the technology. Given the complexity of AM antenna systems, these costs can be higher for AM stations than FM stations. Where are beleagured AM broadcasters supposed to find that kind of money?
Furthermore, the national HD Radio receiver penetration rate stands at a paltry 1%, nearly 10 years after the technology was first authorized for use by the FCC. None of these receivers can decode a fully-digital HD Radio signal – they were all designed to work with the “interim” hybrid analog/digital broadcast configuration on the air today. Repeated surveys of radio listeners report little to no interest in the technology, either. Is it realistic for a beleaguered AM broadcaster to forsake their (dwindling) analog audience for a (non-existent) digital one?
From a technical perspective, HD proponents tout the fact that adoption of all-digital transmission will reduce an AM station’s spectral footprint (from 30 to 20 kHz). While true, the fully-digital signal still occupies twice the space of a purely analog AM signal (10 kHz).
Adjacent-channel interference, especially at night, has been a significant problem with AM-HD, and many early-adopters of the technology have backed away from or abandoned it precisely because of this problem. All-digital AM-HD reduces the interference induced by design but does not eliminate it – a relative, not absolute, “improvement.”
This testing, if it occurs, will be interesting, but does not portend some sort of imminent radical change to the use of the AM band. When it first authorized the use of HD technology, the FCC explicitly noted that radio’s digital transition would be governed by marketplace forces, not regulatory mandate.
Marketplace forces have instead led AM broadcasters to invest heavily in chains of analog FM translators to improve their coverage, not into HD Radio. Any test, “successful” or otherwise, of the all-digital AM-HD mode is unlikely to move the FCC away from its noninterventionist position.
Rather, this experiment is more for the benefit of the NAB’s task force on the future of AM broadcasting, which is considering a plethora of options to rejuvenate or repurpose the band for the 21st century.