Commentary: Return MW to What It Was Born to Do
     

This is part of a Radio World series in which we share industry opinions about AM revitalization.

The thing about the medium waves is that there isn’t very much you can do with them.

Remote controls, high data rate links, phone calls are all rather useless at MW. Unlike UHF, no one wants to pay anyone to clear out any chunk of any spectrum below 3 MHz for any new technology or service. The whole MW band (300 kHz–3 MHz) is less than half the bandwidth of a single TV Channel.

It seems as if virtually half of all the noise in the entire radio spectrum lands in MW. Efficient MW antennas inconveniently measure in the hundreds of feet.

MW/AM was reinvented at least once before. The original 1920s link budget had a few 250 Watt class transmitters on clear channels being received by long-wire antennas strung up to the silos on radio quiet land. The current link budget is kilowatts being received on ferrite loops and tiny wires buried in windshield glass.

REVITALIZATION

Even MW’s good traits are a mixed blessing.

At night, MW stations can cover the continent. Good if there are desolate places to reach and few stations (think agricultural 1930 America) … not so good if that coverage is just interference for other stations (think today, post urbanization and AM’s birth control issues).

VHF and UHF are much better behaved. They better stay in their markets, are high fidelity with low noise, and exhibit good penetration (MW’s aperture effect won’t even let it go under a bridge or through an open window).

So far, any attempt to “compatibly fix” the AM band with digital technology loads two adjacent channels with digital noise for everyone that it attempts to save, and it doesn’t seem to work that well at distances at night. Any conversion to all-digital would make zillions of radios into decorative furniture.

Besides, listeners looking for more stations to listen to can get an infinite number via the Internet right now, making the idea of running out to buy a new digital MW radio feature seem unreasonable. Oddly enough, if one just has to have more broadcast stations, and too many stations aren’t necessarily a good thing, the old TV spectrum adjacent to the FM band is much underused.

So, let’s just agree that trying to make MW into something that can compete with VHF, Internet and satellite is … well … as silly as building in a flood plain and expecting to not float away periodically. However, moving all AM stations to the old and much underused VHF TV slots works just fine.

Could it be that unwinding the MW/AM service with the goal of providing a few simulcast (from their new VHF allotments), wide area coverage and some really very accessible community low-power services is a more desirable revitalization of the MW band?

MY TWO CENTS

I would do two other things with the MW/AM band.

First, I’d provide space for a low-power AM service with a very low barrier to entry.

There really should be a way that any school, church, travelers information service or what-have-you can broadcast for a few miles for not a lot of money or brain damage, when they want, in such a way that it doesn’t hurt anyone. The top of the MW/AM band is perfect for that. One might even split that unused 1700–1800 between the hams and hyper-band broadcast AM. One might make this unlicensed and lightly regulated.

The other tweak is making all the big AM guys suppress one sideband.

Put a 1000 kHz in New York and Los Angeles, but on opposite sidebands so a good radio here in Denver can select between them. Let every top-100 metro have one or two 250 kW services, and not a lot else. Let every state have another one or two boomers.

Using the sideband technique, we have essentially 200 clear channel stations, giving every location a dozen or so daytime services and of course 200 nighttime. Canada and Mexico, which have more MW needy territory to cover, might play along, considering that a MW radio in much of the world receives nothing at all as MW services have been retired. In fact, Canada and Mexico should have more of a share of MW than the U.S. does in a fair world.

Odds are that this revitalized MW service would result in an interesting and convenient service that better answers the public interest, convenience and necessity. Even marginal AM stations move to better spectral ground too. Even the syndication guys win with FM (or digital) VHF signals in their markets, backed up by the occasional wide-area MW simulcast service for the truckers and denizens of the deserts and north woods. This is a case where we should move from flood plane to hilltop and build nicer places.

But mostly, a world of many interference-free diverse voices (all also available locally on VHF simulcasts) seems a better revitalization of the MW band than does a cacophony of sizzling digital wideband signals battling the laws of nature and nighttime propagation in an attempt to deliver a purely local service into places where MW just won’t go.

Truckers, campers, DXers, arm chair travelers, ultra rural residents and owners of antique furniture-quality AM radios, two dollar transistor radios and marginal MW stations … all win. That leaves only the digital-on-MW folks in the cold. Let’s hope they will be happy with being able to do all-digital on the VHF expansion and migration.

Let MW return to what it was born to do: a handful of low-fidelity services with divergent voices to the distant corners of the continent ... a place for the unique voices of distant lands. MW is not incurably sick, and extraordinary high-tech resuscitation is not indicated.

The author is a broadcast engineer active in industry education and cutting-edge technology, mostly on the streaming and video side. His first love is AM radio. He says he has four 1,800-foot Beverage antennas and is “rebuilding a Gates BC-1F like some people rebuild old Mustang convertibles.”

Comment on this or any story. Email radioworld@nbmedia.com with “Letter to the Editor” in the subject field.


Rating People: 14   Average Rating:     
Comment List:

I agree let AM do what it does best. Consider doing way with directional arrays and relax the rules on antenna efficiency and instead base compliance on measured signal strength. Allow natural attrition on AM and encourage the high power stations to improve quality of emissions. Low power community radio should be allowed to operate with simple antennas but provide sufficient geographic separation and enough radiated power to serve the community at night and overcome sky wave interference. AM broadcasting has become over complicated and many of the technical regulations seem to cause more problems then they cure. Its like taking more and more drugs to overcome the side effects of the original drug...! European AM local and regional stations do not require DA's and reduced nightime power!
By Chris Turner on 3/26/2014
If the Commission decides that it cannot accommodate low power stations on the AM broadcast band, it still can provide such a neighborhood service using the following aspect of the ionosphere. There are several of the short-wave broadcast bands that provide world-wide shortwave propagation during the day time. At night, these bands do not provide this long distance broadcasting. The Commission could allocate specific frequencies in these daytime short wave bands for nighttime local broadcasting by local residents. Thus while the short wave bands were inactive at night, the local communities and neighborhoods could broadcast locally using very simple low-power short wave AM transmitters. Neighborhood residents would operate and maintain the stations.
By Nickolaus Leggett on 2/20/2014
Great minds think alike... We should craft our own NPRM!
By Scott Clifton on 2/19/2014
If you want to mandate something for AM I would bring back AM Stereo. As a chief engineer of a former Kahn AM Stereo station I know first hand just how good AM can sound - of course you'd have to get rid of the NRSC-1 mask, too. The low power AM would be idea for schools. I ended up building a Part 15 campus limited station for a high school while a local NPR affiliate occupies 3 AM's covering 20 miles plus and this is besides two main FM signals and a barrage of translators. Let the kids provide a local radio voice that will actually serve the townies!
By Bill DeFelice on 2/1/2014
I'm happy to read an intelligent prospective on the AM band. Turning the AM band into an all-digital wasteland not only turns every analog AM radio into a doorstop, but likely leaves the elderly and everybody else without a way to get local news and information outside of having to rely on the FM music stations. It also seems a bit disingenuous that the manufacturer of such digital technology is lobbying for its acceptance, knowing quite well that they will be on the receiving end of forced royalty payments if their system were to become mandated.
By Bill DeFelice on 2/1/2014
Let MW/AM radio do what it does best! Yes, but two things get in the way. 1) AM radio doesn't have to be low fidelity but it is trapped by the limited bandwidth of most AM radios. So any investment in the transmit chain will fall on deaf ears. So this still condemns AM to sports talk & news with music on FM or more likely Spotify 2) 200 nightime channels sounds a great idea until programme syndication occurs. What's the point of 200 distant copies of Coast to Coast AM simultaneously filling the band. This could be addressed as part of a revitalisation plan that limited the role of national syndicators at night. But of course that leaves each station with the increased cost of programming....
By Steve Whitt on 1/31/2014

Post your comment

Your Name:  Required
Your Mail:       Your email will not be published.
Your Site:    

max. 800 characters


Posts are reviewed before publication, typically the next business morning. Radio World encourages multiple viewpoints, though a post will be blocked if it contains abusive language, or is repetitive or spam. Thank you for commenting!