According to a leaked memorandum from ABC/Citadel‘s executive chief engineer, all AM stations in the company’s stable have ceased broadcasting in digital at night, effective immediately. The memorandum does not give specifics, but follow-on reports cite interference between AM stations on adjacent channels as a major factor for the decision. Interestingly, some suggest Citadel executives knew such a problem might be in the offing, but they went ahead and turned on their digital signals at night anyway.
This is a major setback for the adoption of HD Radio, especially on the AM dial, and Citadel is the first large broadcast conglomerate to back away from full deployment of the HD broadcast technology. Although the company’s gone out of its way not to characterize its move an indictment of iBiquity’s proprietary digital broadcast standard, the problems with AM HD broadcast interference are well–known and -documented.
Apparently, since the FCC’s authorization of nighttime AM-HD broadcasts earlier this year, the number of complaints about interference between stations has risen dramatically, and affects all classes of AM stations – from the 50-kilowatt “clear channel” blowtorches to the smallest operations.
Because the interference potential of HD Radio signals (and especially AM-HD signals) is a fundamental flaw of the technology itself, it’s hard to see how a “workaround” might be produced to fix this problem, outside of going back to the drawing board and redesigning the entire HD broadcast protocol to not be as bandwidth-hungry as it is. HD-capable AM stations have already squeezed the bandwidth of their analog signals in order to accommodate the HD sidebands, even beyond the point of fundamentally degrading analog audio quality. Since a wholesale redesign of the AM-HD protocol is highly unlikely, perhaps AM stations should consider HD alternatives instead? Unfortunately, the FCC does not seem predisposed to consider this.
As radio’s technology of the future, HD could very well be a waste of time: listener knowledge about and adoption of new HD-capable receivers is abysmal (more people listen to Democracy Now! every week than listen to a digital radio broadcast); the price and quality of said receivers is mostly-abysmal; and even broadcasters are coming around enough to openly admit that AM-HD is an afterthought – radio’s digital future will almost entirely exist on the FM band. This is a major factor, I believe, as to why the NAB and its member-stations are pushing so hard for the FCC to freely give FM translators to AM stations.
In a nutshell, HD Radio is far from dead, but it would appear that, in some respects, the writing is already on the wall.
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