Media Access Project: One Page Summary of Technical Low Power Radio Issues Considered by the FCC

One Page Summary of Technical Low Power Radio Issues Considered by the FCC

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January 2000

Background.  Many incumbent broadcasters claim that, although they support 
low power radio in theory, they fear these new stations will harm current 
broadcasts or interfere with conversion to digital radio. Although broadcasters
spent hundreds of thousands of dollars on technical studies, they have not
proven their doomsday claims. The technical debate centers on the Federal 
Communications Commission's (FCC's) interference protection standards, 
which govern the spacing, similar to cushioning, between radio stations.  
The FCC proposes to alter these standards by relaxing both "second adjacent" 
and "third adjacent" protection, but leaving all other protections in place.  
Broadcasters oppose all changes.  Other parties agree that the FCC's current 
rules are probably outdated, and may be safely altered.  

Technical Proponents.  A coalition of national religious organizations, led by 
the United Church of Christ, Office of Communication, hired a nationally-
prominent radio engineer, Dr. Theodore Rappaport of Virginia Tech to study 
low power radio and to conduct rigorous review of the technical documents 
submitted to the FCC by LPFM opponents.  

Dr. Rappaport found that low power radio was technically feasible.  While he 
agreed that the largest proposed stations, 1000 watt stations, require full 
interference protection, he concluded that, because stations of 100 watts 
and fewer are so small, no harm would occur if both second and third adjacent
protection is relaxed for those stations.  

He also concluded that:

Over 600 low power radio stations under 100 watts can be deployed in the top 60 markets in the United States without harming current radio broadcasts,
under the worst scenario, 1.6 percent of the listeners served will experience interference, and
the listeners that experience interference may be able to avoid any difficulty by repositioning their radios.

Dr. Rappaport also criticized several aspects of the broadcast industry's studies.  
Some of his findings are:

The National Association of Broadcasters study tested radios that were doomed to fail -- they selected radios that did not meet their own performance standards in the absence of new low power radio stations or other interference.
The NAB produced maps of potential interference based on a radio that does not exist.
The Consumer Electronics Manufacturers Association tested a sample of radios that was not representative of the radios in use today, according to its own data.
The NAB inflated the number of listeners who would experience interference by double, triple, and quadruple counting individuals.

Conclusion. The modified proposal that the FCC adopted -- relaxing third adjacent but not second adjacent protection and no 1000 watt stations -- contains a wide margin of safety for current broadcasts. It responds to all concerns set forth by digital radio proponents. Moreover, the FCC has experience with relaxed third adjacent protection in tight markets in the northeast, such as New York City. While the FCC could have gone further, it cannot be accused of failing to safeguard the spectrum.

More detailed technical information, including the complete study, is available here.

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