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Commentary: AM Efforts Should Include Tech Solutions

Revitalization attention is welcome; DRM should be considered too

Paul Thurst The effort by at least two FCC commissioners to do something about the lagging quality of the AM broadcast band is laudable. Since the subject was broached before the spring 2013 NAB, many ideas on exactly how to make a meaningful improvement to the AM band have been put forward.

The FCC is currently circulating a NPRM on the subject, which includes the following basic ideas:

1. Open a one-time filing window for AM license holders to acquire an FM translator.
2. Relax community coverage rules for AM licensing, allowing greater flexibility for transmitter siting.
3. Eliminate the “Ratchet Rule” used in nighttime allocation studies for new facilities.
4. Permit more widespread use of modulation-dependent carrier level technologies by eliminating STA requirements.
5. Reduce minimum field strength requirements by 25 percent, allowing the use of shorter towers.

Those proposals may indeed save an AM license holder some money, but none of them do anything to improve the technical quality of AM broadcasting.

Placing electrically short towers further away from population centers will reduce signal levels. MDCL will also reduce signal levels somewhat, depending on how aggressively it is used. Since one of the main technical flaws with AM broadcasting is the prevalence of electrical interference, taking steps to further reduce signal strengths over population areas seems counter-productive.

Of the three, MDCL is reversible, whereas poor transmitter siting and short towers are more likely permanent flaws in a station’s technical facilities.

These ideas were first put forward in 2009 by the Minority Media Telecommunication Council as a rescue plan for radio. Reducing costs for AM broadcasters is generally a good idea, but it is not synonymous with saving the AM broadcast band.

Some people have been excoriated for pointing this fact out. Sorry, it is beyond unhelpful to say nothing. Rather, I would posit that the industry regulators might want to know exactly what they are doing before they change the regulations.

One simply has to look at the history and the current state of the AM broadcasting band for an example of what effect technically flawed regulatory decisions can have.

The use of FM translators to simulcast AM stations is not necessarily a bad idea, especially when it comes to Class C and D stations that have little or no nighttime coverage. In those situations, the increased service to the city of license would be a good outcome.

The other idea that is being talked about is the conversion of the AM band to all-digital HD Radio. While some type of digital radio may be inevitable, there are some serious issues with iBiquity’s HD Radio. It is proprietary and will remain proprietary in the foreseeable future.

If broadcast station licenses are indeed a trust granted in the public interest, how can one company, by way of controlling patents, control all radio broadcasting transmissions within the country?

If all-digital transmission is seriously being considered as a way to improve the AM band, other technologies should be investigated. DRM (Digital Radio Mondiale) has been in development in Europe since the early 1990s and is specifically designed to fit into 9 kHz channel spacing without creating copious sideband interference. Further, DRM is non-proprietary. Since so much hangs in the balance, would it make sense to at least test DRM and compare it to the HD Radio test results?

Paul Thurst is a broadcast engineer with 25 years’ experience working in the greater New York area. His blog

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