Jeffrey Krauss
Jeffrey Krauss
President of
&Technology Policy
The newly-elected Congress is in session, and as always, the first thing it does is to introduce new legislation. Some of the bills deal with "old favorites" like net neutrality. But some get into complex technical matters like radio interference. The sad thing is that our elected officials have neither technical training nor technically-trained advisors, yet they want to meddle in these complex technical issues. The FCC and other regulatory agencies DO have both the technical training and technically-savvy staff who can deal with these complex issues. Here are two pieces of legislative meddling that caught my eye.

I wrote about the FCC's "white spaces" proceeding in my November 2006 column. The FCC expects to start deployment of unlicensed transmitter devices on unused TV frequencies starting in February 2009, coincident with the end of the digital TV transition. But there are serious unresolved interference issues. These unlicensed transmitters will have to be designed so that they don't cause interference to TV reception, to unlicensed wireless microphones, or to cable headends that receive weak off-air signals from distant TV stations. Nobody has shown that it is possible for inexpensive unlicensed transmitters to sense whether there are TV receivers or wireless microphones in use nearby. The FCC is asking for comments on possible approaches, and at the same time, testing the interference rejection capabilities of digital TV receivers. So it seems like the FCC is doing a pretty thorough investigation of a pretty complicated issue.

But now we have bills introduced by Senators Kerry, Sununu and others that would force the FCC to adopt rules that make this spectrum available, even if the technical investigations haven't been completed. According to Kerry's press release, the Wireless Innovation Act "specifically requires the FCC to permit license-free use of the unassigned broadcast spectrum between 54 MHz and 698 MHz within 180 days of enactment," regardless of the status of the technical investigations.

The press release also says, "In the spirit of President Franklin D. Roosevelt's New Deal 'Rural Electrification' package, which expanded access to electricity for thousands of American families, Kerry's bill would serve communities large and small, enabling the delivery of broadband that will connect business owners with their customers, students with dynamic new learning resources and first responders with victims in crisis." Wowee!

And then there is the Emergency Amateur Radio Interference Protection Act, introduced by Congressman Mike Ross. This deals with power line communications, or Broadband over Power Lines (BPL), as the FCC calls it. The FCC started an inquiry on the technology in 2003 and adopted technical rules in 2004. BPL technology can be used within a home to provide a local area network, competing with WiFi, and can also be used over outdoor power lines to provide an Internet access service, competing with cable modems and DSL. BPL technology generally operates on the frequencies between about 4 MHz and 50 MHz. Electric power lines were not designed to carry radio signals at those frequencies, so some radio energy leaks out.

FCC rules impose the same radio emission limits on BPL as already apply to personal computers and other digital devices. They require that companies operating Internet access service using outdoor BPL technology must take a variety of measures to eliminate interference if it should occur, including using adaptive filtering to notch out particular frequencies. The amateur radio community opposed BPL from the very beginning, and was not satisfied with the FCC's technical rules.

Congressman Ross' bill requires the FCC to re-study some of its 2004 technical decisions. It requires, for example, that the FCC re-study "the variation of field strength of BPL service signals with distance from overhead power lines, and a technical justification for the use of any particular distance extrapolation factor." This is an attack on the FCC's decision to use a 40 dB per decade factor for the decrease of field strength as the distance from the power lines increases. The radio amateurs wanted the FCC to use 20 dB per decade, which would imply that BPL emissions cause interference at a greater distance from the power lines, but the FCC decided that the existing extrapolation rule that applies to PC emissions also applies to BPL emissions.

And it requires a re-study of "the depth of adaptive, or 'notch' filtering for attenuating normally permitted BPL service radiated emission levels that would be necessary and sufficient to protect the reliability of mobile radio communications." This is an attack on the FCC's decision to require 20 dB of notch filtering; the amateurs wanted more than that.

I think it's reasonable for congressmen and senators to introduce legislation on policy issues like net neutrality. But radio interference? Give me a break. Do you think that Rep. Ross knows what notch filtering means? Congress should leave these issues to those expert agencies that are trained to deal with them.