To date, only a handful of stations have opted to bear the extra expense and wear on equipment associated with boosting the output on their HD channels — with good reason. Now it seems that part and parcel of that boost is an accompanying degradation of the analog signal, as reported in this post, entitled “Look Before You Leap,” on the Radio World website. Author Dave Hershberger, a senior scientist at Continental Electronics, leads off this way:
FM broadcasters may now increase their average digital signal power, in most cases to levels as high as 10 percent of the analog power. Transmitting more digital power will certainly increase the digital coverage area and reduce digital dropouts. However, there may be some unintended consequences, which every broadcaster will have to evaluate before increasing digital power… One negative effect is the way in which increased digital power will mean increased envelope modulation of the linear sum of the FM and OFDM signal components. Peak-to-average ratio reduction algorithms may be called upon to work harder to reduce the envelope modulation… Elevated digital power will also aggravate self-interference to the analog signal [emphasis added].
Dave then plows into a bunch of engineer speak, heavy going for the uninitiated, but the upshot is that this power boost would mess with the station’s analog channel — contrary to what the claims have always been from those flogging the system. They’ve always claimed that while it may mess some with the AM band, hey, no problemo with FM.
Stick a Fork in It
In other related news, word out of Europe is that iBiquity’s flagging fortunes there took a fatal blow. The one place that experimented with IBOC — Switzerland — just pulled out. The internet brims with stories, but this post on Radio World says it most succinctly: “Swiss HD Radio Project Dead.” The article reports that Markus Ruoss, owner of Sunshine Radio and head of the HD Radio project, “said that for himself ‘the HD Radio chapter is complete.’” He thanked investors for the $1.5 million they invested in the crapshoot.
Jack Hannold sends along links to German coverage, for those who sprechen Deutsch:
For their part, Bob Struble and iBiquity seem to be backpedaling furiously. This post on the website This Week in Consumer Electronics carried this waffle from the master chef:
Radio broadcasters are waiting for further growth in the installed base of HD Radios before they resume a more aggressive pace of station conversions to digital broadcasting, said HD Radio developer iBiquity Digital. “Broadcasters want to see some more eggs before they take the next step,” iBiquity president/CEO Bob Struble told TWICE.
Meanwhile, back at the ranch, Paul Riismandel of Radio Survivor intoned a death knell for HD on the AM band in an article entitled “HD Radio on AM — Not Worth It,” leading off with his conclusion from his test of the FM band (contrary to all the swag broadcast by myriad investors in the scheme):
One of the supposed advantages of HD Radio is improved fidelity over analog. As I observed in my listening test of HD on FM, there’s almost no real improvement for HD over the analog signal.
Paul noted that in Chicago, iBiquity claimed to have seven HD channels broadcast on the AM band, though he was only able to pick up three, even after severe manipulation of his antenna. A comment by Greg Smith led him to a post that showed two of the stations no longer broadcast in HD. His conclusions?
Much more so than with FM, I consider HD Radio on AM to be mostly useless and not worth the effort. It’s especially not worth the loud digital hash noise I receive on my analog-only radios on the frequencies adjacent to the HD stations. It’s like a line of digital litter strewn across the AM radio highway….
While I’m willing to work a little to optimize reception, I’m not really willing to go to great lengths for the purpose of the test. I’m looking at HD Radio not from the standpoint of an average radio listener, who I believe is generally not willing to work too hard to receive an HD signal.
Filed under: The HD Radio scam |