All-Digital AM Tests on the Table

Members of the NAB Radio Engineering Committee are pondering testing iBiquity Digital’s all-digital AM system.


The idea is one of several that has been bandied about, I hear, as part of the overarching goal of helping medium- and small-market AMs without a powerful signal to remain economically viable.

Beasley has committed to finding a station to test on and at least two other broadcast groups have as well, Beasley Vice President of Engineering/CTO Mike Cooney tells me.


The key is finding an underperforming station and turning off the analog temporarily in order to test the all-digital system, both day and night.   


Years ago, I remember iBiquity conducted tests of its AM all-digital technology and anecdotally reported an increase in coverage. But that was with the HD gear of several generations ago. It would be interesting to see all-digital AM performance with the HD Radio gear of today.


IBiquity has also said for years that the interference issues inherent with the AM band could potentially be improved with an all-digital system.


Other potential upsides? With all-digital “your bandwidth goes from 30 kHz back town to 20 kHz,” said Cooney, who adds an all-digital AM system also requires less transmission power.


Granted, some AMs may need equipment upgrades to make an all-digital chain work, however, knowing what you’d need would help you plan, I think.


Beasley is especially interested in results, having previously turned off the digital on several of its AMs due to interference concerns, we’ve reported.


The idea of the testing is to get some real-world data over a sustained period of time and quantify the results. “We would do before-and-after signal measurements to compare analog and digital coverage differences,” he tells me. Testing would also determine whether an all-digital signal caused any first-adjacent interference, or improved existing interference.


Drive tests would be conducted in rural and city areas in several markets.


Committee members still need to identify test stations.


The idea of testing the all-digital system is intriguing as struggling AM owners try different things to keep their stations relevant as consumers increasingly turn their attention to FM and online options. While big-market AM powerhouses remain profitable, the economic picture is not so rosy for other AMs, some of which have increasingly turned to rebroadcasting their signal on FM translators.


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Comment List:

Last I saw, AM DRM is alive and well and being deployed in most of the world. In fact, LBA has been delivering DRM antenna systems for a couple of years now. So what's with the Ibiquity system that makes it worthwhile to break with the current world "standard"? Everything an AM needs to broadcast is available now, even a receiver base is emerging. Shortwave has been going strong on a conversion to DRM, as well. I hope this isn't another "not invented here" exercise like our digital television fiasco!
By Lawrence Behr on 7/5/2012
To maintain relevance, and ultimately regain, or at least stabilize listenership at current levels, AM radio as we know it today needs help on several fronts. The best solution would be a package of remedies that could simultaneously add to receiving quality of current stations while most likely transitioning to a new digital broadcast band for the future. Here are a set of suggestions that I believe could in whole, or in part, add health and longevity to the service. 1. We should seriously reevaluate the concept as proposed by Richard Arsenault of an across the board power increase for all AMs Allowing more stations to punch through the interference that so effectively renders stations unlistenable. The FCC was extremely quick to dismiss the proposal without even opening it for comment, yet offers no new solutions either. The power increase may not be the "10 times increase" as wished for, but there may be a reasonable middle ground at which improved signals can be cost effective
By Dave Webster on 7/4/2012
The $5 analog AM radio that will run for days on a 9volt battery has been the last ditch save-all for disaster survivors (aka Hurrican Katrina and WWL). Digital radios thus far have been too expensive and power-hungry and without user-replaceable batteries. As tempting as an all-digital AM sounds, it is a bad idea removing the last inexpensive lifeline to live radio by taking it digital and rendering hundreds of millions of analog AM radios useless. I'm the opposite: I believe we should be moving AM's that want to move to FM to Channels 5&6 and the remaining AM stations all become wide bandwidth AM SuperPower stations of 750KW+ and run analog AM stereo without any digital components other than using the stereo pilot tone for low-speed data for ID and EAS text only.
By John Frank on 7/3/2012
I remember the old XM commercials that said something to the effect of "We're not AM, We're not FM, We're XM". I imagine an medium wave station saying: "We're not AM, We're not FM, We are digital. Digital 1480." That is an interesting idea if the promotion is good, and that means that the promotion would have to be better than the retarded iBiquity promotion of saying "HD Radio". iBiquity is the reason that digital radio has not been very successful.
By Marvin Mysterio on 6/30/2012
Going all digital has drawbacks, too: --AMs with multi-tower DAs might have trouble passing the bandwidth, so a re-build of the DA system might be necessary. --Turning off the amplitude-modulated signal means that all radios currently out there would become obsolete and useless. And there will NOT be a scramble by consumers to buy new radios as consumers would just learn to live without the AM band. In short, a switch to all-digital is more likely to just be the death knell of the AM band (which may be dying anyway). The only clear party to benefit would be Ibiquity, who would make tons of bucks selling all that equipment and raking in the royalty fees. This is a really bad idea.
By Phil Boersma on 6/29/2012

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