The author is shown in 2010 conducting an inspection at the top of KRKO’s newly replaced radiator. The year prior, two towers had been brought down by a vandal using an excavator.The author is licensee of 50 kW AM stations KRKO and KKXA in the Seattle market, incoming chair of the Washington State Association of Broadcasters and a former NAB board member. He participated in the recent NAB Labs driving tests of all-digital on the AM band. Opinions expressed are his own.
All-digital transmissions on the AM band are better than analog. However, all-digital operation, if adopted, would only be a Band-Aid for the unstoppable rising tide of electromagnetic erosion that ultimately will wash away the coverage and signal improvements of digital.
History weighs against achieving the consumer receiver adoption levels necessary to realize the benefits of all-digital ahead of this electromagnetic tide. Further, a majority of directional AM licensees will be unable to participate in its benefits for reasons unrelated to the technology.
For those who seek a permanent solution, migrating occupants of the band to vacated VHF spectrum remains the only option anyone should consider truly “permanent.”
TIME IS AGAINST US
In the 1920s, our station’s signal, then at 250 watts, received daytime reception reports from Vancouver, B.C., to Portland, Ore. Today, we need 50,000 watts to reach 60 miles from our studios in Everett to listeners in Tacoma and Bellingham. Electromagnetic noise in the AM band is getting worse. In-car cell phone chargers, computers, LED lighting and a host of other electronics interfere with the band and shrink coverage areas.
Digital overcomes some of these issues for now; but how long will it last against an electromagnetic barrage that is indifferent to analog or digital on the AM band? The industry appears poised to forge ahead with AM digital, as opposed to VHF migration; so, the next question becomes whether consumer adoption can occur quickly enough to realize the benefits.
We tried to buy consumer tabletop AM HD Radio receivers ahead of our all-digital test broadcasts. None were available — not at Best Buy, not on Amazon, nor were any used radios available. Zero. And there has never been a portable HD Radio-enabled AM receiver.
No digital AM band receivers (let alone analog) will ever appear in cell phones because of chip interference and lack of real estate for an antenna.
Meanwhile, in Seattle, receivers with HD Radio technology of any kind represent only 5 percent of the market after 10 years of effort.
Consider that for analog FM, consumer adoption and receiver penetration took nearly five decades. Given the current trajectory of HD Radio-enabled receivers — and absent a digital receiver chipset mandate, or at least an FM digital transmission mandate that brings AM chipsets on its coattails — we likely would need three decades to achieve critical receiver mass so AM stations could go all-digital with a sufficient installed base of receivers.
Further, even if 100 percent of Americans today had a radio with an HD Radio chip, a mandated conversion to all-digital on the AM band would be an immense burden on licensees of directional stations.
Compared to omnidirectional stations, AM digital implementation on directional stations is far more costly depending upon the age of the facilities and the number of radiating elements in the array.
And digital implementation costs are asymmetrical from one directional facility to the next. For example, there are directional AM stations with short-spaced radiators that would have to relocate their radiators physically to make digital work. That’s like building a new directional antenna from scratch, an awful proposition.
These issues are not insurmountable; but a mandated all-digital implementation could cause a significant number of directional licensees to turn their stations off when faced with the specter of investing to make their facilities ready to pass digital.
SUNRISE OR MIGRATION?
What about an AM “digital sunrise” process, in which all-digital stations would operate on the band alongside analog signals, at least for some period of time?
This would be a mixed bag at best. All-digital is far more robust than current hybrid transmissions. But the sunrise scenario could make the band sound worse to listeners with analog-only radios and could hasten audience flight.
All-digital signals on the AM band sound like 1990s phone modem noise to analog radios (remember the “whoosh” sound after the handshake?). The sound is audible in the sidebands of stations using the technology now. The benefits of stereo separation, better coverage and signal consistency would be realized only by the small portion of the population capable of receiving the all-digital transmissions.
A more elegant solution would be to use the next four decades to migrate occupants of the AM band to abandoned VHF spectrum, meaning current Channels 1–6, and simplify the user experience.
How might this work? The commission could require licensees to broadcast in digital on the FM band from the moment they turn on their new transmitters as the “spectrum cost” of migration. Stations would be allowed to simulcast their AM signals until some future day that the FCC retires the AM band. This would provide further incentive to receiver manufacturers to produce chipsets capable of receiving HD Radio or Digital Radio Mondiale, a topic for a later discussion.
FM ANALOG SUNSET
But if vacant VHF is off the table for licensees of the senior band, then we need to pursue the idea of an all-digital transition, and there are some ways to get AM stations to the all-digital altar.
An “analog sunset shot clock” for the FM band is the fastest way to drive receiver manufacturer implementation and FM adoption. Digital technology works really well on the FM band and takes little to implement. How does this help AM stations? A mandate that all FM stations go digital would facilitate more rapid receiver deployment (presumably with mandated digital AM chipsets). This can set the stage for addressing the needs of the AM band. While the commission is at it, AM auction windows should be ended permanently.
An all-digital mandate on the AM band could push a large number of directional operators — half or more — out of business, depending on the timing; because the bulk of AM stations in the United States are running with worn-out equipment and transmitter sites, and the revenue supporting those stations is too thin in many markets to justify new investment. The mandate would cull those who can’t or won’t make the upgrade, helping the transition.
But while all-digital on AM will make the band competitive, licensees shouldn’t be forced into bankruptcy to do it; incentives would be required.
If we decide digital is the future of the band, we will need to craft a plan to push for significant tax incentives or other rewards for licensees who don’t wish to go digital to turn in AM licenses. We can’t bifurcate the AM band into digital and non-digital stations.
Perhaps the incentive is some form of deferrable, dollar-for-dollar reduction in tax payments, predicated upon the population of listeners within the daytime 0.1 mV/m contour of a station based on M3 conductivity multiplied by a cost-per-listener based on FM valuations. AM licensees would turn in their licenses for this kind of lucrative incentive. Licensees who turn in their licenses deserve meaningful compensation to exit.
Licensed AM spectrum surrendered for tax incentives should never be used for radio again. When the surrender period is over, remaining stations should be allowed to improve their facilities by increasing power or moving where possible. And it’s been suggested some kind of low-cost industry financing could be put in place to get the equipment out to stations and facilitate upgrades.
With these kinds of plans in place and with national digital receiver penetration presumably by that time above 75 percent, an analog AM sunset could be implemented 20 to 30 years from now and licensees could weigh which way they want to go, meaning they’d have a choice of migrating or taking the incentive to go silent.
Frankly, if we got lucky and went from 4,700 AM stations down to 700 stations, the AM band, and radio, will be more sustainable.
Sounds a little crazy doesn’t it? Getting to an all-digital AM band is crazy, and it’s why we should advocate for migration, and a digital mandate on the other end. Once you get FM spectrum for your AM, you should be required to implement HD; it can be HD the way it is now, with an analog main and digital HD1; but digital has to be baked-in from the start.
There is no doubt after our experiences with the testing that digital on AM is better than analog AM, for reasons you’ll learn at the NAB Show in April. But the question remains: How long will that advantage last?
We’ll continue our digital broadcasts because the warm sound quality, stereo separation and consistency of the digital signal benefit our listeners who have HD Radio-enabled receivers; but as an industry, we should only “go there if we must” because a better, truly permanent solution is before us in migration.
What do you think? Comment via email to firstname.lastname@example.org with “Letter to the Editor” in the subject field.