NTIA Tips Hand on its Additional BPL Findings:

National Telecommunications and Information Administration (NTIA) Acting Administrator Michael Gallagher says his agency's complete Phase 2 broadband over power line (BPL) study is targeted for release later this year. In remarks May 17 at the United Telecom Council's "Telecom 2004," Gallagher hinted at some findings in the Phase 2 study, which NTIA says will provide "additional guidance" on contending with BPL interference. The NTIA advised against putting the present FCC rule making proceeding on hold until release of its full Phase 2 report, however.

"Key Phase 2 technical analyses have been completed," Gallagher told the UTC gathering, "and the findings are appended to NTIA's comments on proposed rules." The NTIA has posted its Phase 1 BPL study on the proceeding, ET Docket 04-37, and has indicated to the FCC that it will file its comments on or about May 28.

Responsible for developing telecommunications policy for a White House that's promoting BPL, as well as for administering federal government radio spectrum that could be affected by the technology, the NTIA finds itself with a stake in both sides of the BPL controversy.

The principal concern, Gallagher acknowledged, is that BPL systems might interfere with federal government and other radio services. The NTIA's Phase 1 study showed that interference risks already are high under existing Part 15 rules. Among its recommendations for reducing interference were frequency shifting and notching as well as "refined compliance measurement procedures."

Gallagher says the NTIA's Phase 2 study has determined that BPL aggregation (ie, total emissions from multiple BPL systems) and ionospheric propagation "is not a potential near-term problem." The agency predicts that millions of BPL devices can be deployed under the rules the FCC is expected to adopt--probably later this year--before ionospheric propagation and aggregate BPL emissions become an interference issue.

ARRL CEO David Sumner, K1ZZ, says he's curious to hear the NTIA rationalize its "near-term" assertion. "Does this mean it's okay to go ahead with a bad idea if the problems it causes are sufficiently far in the future?" he asked.

The Phase 2 study also will evaluate the effectiveness of proposed Part 15 measurement techniques and recommend a "height-correction factor" of 5 dB to BPL measurements made at a height of 1 meter, Gallagher said. The NTIA acknowledges that peak field strength is as much as 20 dB higher--a factor of 100--than the peak measured at a height of 1 meter under current Part 15 rules. Because the peak does not occur consistently at a particular distance from a BPL device along the power line, the NTIA will advise requiring a peak field strength measurement search along the entire power line at a distance of 10 meters and at a height of 1 meter.

The agency has determined that a moderate-to-high probability of interference exists to a fixed station from BPL power lines at a distance of 450 meters--approximately 1480 feet--and to a mobile station at a distance of 55 meters--approximately 180 feet.

To "fulfill special protection requirements," Gallagher said, the NTIA will suggest "minimal" coordination areas--where a specified authority would coordinate all planned BPL deployment--plus excluded bands and exclusion zones. The NTIA recommends "voluntary coordination" with respect to other radio operations plus "mandatory Access BPL power control, frequency agility and shut-off capabilities" to reduce interference risks and to expedite interference mitigation.

The NTIA further proposes that BPL rules provide for "prompt response to complaints of suspected interference," recasting the FCC's Part 15 shutdown requirement as "a last resort."

"Our BPL study of more than 10 million signal samples shows that solutions exist to all identified BPL technical issues," Gallagher concluded.

That's true, Sumner said, "but only if you include shutting a BPL system off and keeping it off as a 'solution.'"

During a White House meeting May 20, ARRL officials asked the Bush administration to heed its own NTIA experts and back away from its support of BPL. The League also has called on the FCC to put its BPL proceeding on hold to allow more thorough research of its interference potential.

For additional information, visit the "Broadband Over Power Line (BPL) and Amateur Radio" http://www.arrl.org/bpl page on the ARRL Web site.

Source:

The ARRL Letter Vol. 23, No. 22 May 28, 2004

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