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 Previous: In Brief |  Next: Illinois Amateurs Support Tornado Relief, Recovery Efforts; UPDATED: |
 A BPL medium-voltage connection and box. This one is in Cedar Rapids, Iowa. [Alan Erickson, WB0OAV, Photo] |
NEWINGTON, CT, Apr 22, 2004--In an e-mail to the FCC, an electric utility testing broadband over power line (BPL) systems in the Raleigh, North Carolina, area has drawn a virtual line in the sand on how far it plans to go to mitigate interference to Amateur Radio. Responding this week to the FCC about BPL interference complaints from hams, Progress Energy Corp (PEC) told the FCC that his company has, for all intents and purposes, eliminated any harmful interference from its BPL trial site and now complies with FCC rules.
"It is PEC's position and interpretation of the FCC's rules with regard to 'harmful interference' that any interference that may still exist is not 'harmful' as that term is defined by the FCC's rules," Len Anthony, PEC's attorney for regulatory affairs, told James Burtle, chief of the FCC's Experimental License Branch. "This level of interference does not seriously degrade ham radio operation or transmissions or cause repeated interruptions." Some, but not all, of PEC's BPL field trials are covered by an FCC Part 5 experimental license.
The FCC defines as "harmful" any interference that "seriously degrades, obstructs or repeatedly interrupts a radiocommunication service operating in accordance with the Radio Regulations."
Anthony noted that since PEC can modify its Amperion BPL system to totally eliminate interference to fixed stations, "the only impact of any kind upon ham operations is upon mobile operators." PEC concluded that since BPL interference to mobiles would by "very short lived," the company is not causing harmful interference and is in "full compliance" with FCC Part 15 rules.
ARRL North Carolina Public Information Officer Gary Pearce, KN4AQ, suggested this week that PEC has a bit more work to do. He is among local amateurs closely monitoring BPL deployment in the test zones and cooperating with PEC and Amperion to work out any interference issues. Pearce says interference remains on the top end of 20 meters in an overhead-line field trial neighborhood where PEC recently had tweaked its system, but it has not been mitigated at all in neighborhoods with underground power lines. When he visited the neighborhood in the wake of Anthony's e-mail, Pearce said he at least expected to find that PEC had eliminated the 20-meter interference.
"Nothing had changed," he told ARRL. "They were still covering up the top end of the 20-meter band." Interference to 17 and 12 meters had been notched out, but beyond that, BPL interference persisted from 14.290 to nearly 17 MHz, he said, and "fringe" carriers still encroached some 100 kHz into the bottom of 15 meters.
"The signals on the underground lines have not changed at all," Pearce continued. "They were still full-strength across virtually every ham band if you look across the whole neighborhood."
Progress Energy has been operating its "Phase II" trial in three neighborhoods south of Raleigh since early January. The area, in Wake County, is largely rural or lightly settled.
No hams live in the underground-wired neighborhood, so none complained, Pearce said. Early on, no hams in the vicinity of the BPL trial areas filed formal complaints "because they didn't know what the signals were," Pearce said. The handful of BPL interference complaints eventually lodged with the FCC came from Amateur Radio licensees living closer to the overhead-wired neighborhood, and some came from mobile operators.
Pearce said PEC's stance regarding mobile stations "sets a new bar" in interpreting harmful interference. "If you're driving by a power line, you can hear the signal for a mile or so," he added. "It is hardly something that is just going to be transitory."
"Hams have never been asked to accept that level of
interference before," he said.
 (L-R) During a January visit to a Raleigh-area BPL test zone, Bill Godwin and Will Roberts, AA4NC, of Progress Energy; Wake County EC Tom Brown, N4TAB; North Carolina Section Technical Specialist Frank Lynch, W4FAL, and Gerrett Durling of Amperion check out the display of a portable spectrum analyzer during BPL testing. [Gary Pearce, KN4AQ, photo] |
The ARRL's BPL strategy, okayed at a March 13 Executive Committee meeting, calls for the League to seek a radiated emission limit sufficient to protect the estimated 70,000 Amateur Radio mobile stations in the US. The FCC's BPL Notice of Proposed Rulemaking (NPRM) in ET Docket 04-37 is silent with respect to mobile operation, which typically occurs in close proximity to medium-voltage power lines. ARRL field observations using typical amateur equipment have documented BPL interference to mobile stations located hundreds of meters from a BPL interference source.
To date, Pearce says, PEC has not demonstrated the ability "to completely eliminate any interference with fixed ham operators," as it claims it can do. Amateurs in his area remain concerned about the so-called "fringe" carriers at the edge of the BPL spectrum blocks that still fall inside amateur bands at reduced amplitude, he said. They're also troubled by incomplete BPL signal notching in 17 and 12 meters, where, he says, weak BPL carriers remain audible.
Pearce says the North Carolina hams will respond to Progress Energy and the FCC to "disagree with their interpretation of 'harmful interference' and disagree with their conclusion that this doesn't cause interference to a mobile."
While Pearce maintains that controlling BPL in a small trial area like his should not be that difficult, "having BPL buzzing across all the power lines in a large city is another story entirely, and that's what we're worried about."
ARRL CEO David Sumner framed the situation another way. "From the very beginning, the fundamental problem with BPL has been that its proponents have no understanding of the low signal levels that are commonly and effectively used by radiocommunication services," he said.
"If BPL emissions block weak signals that otherwise would be usable, that is harmful interference and they must remedy it. Progress Energy has as much as admitted that they can't. The only thing left for them to do is to shut their system down and get back to their basic business of supplying electrical energy."
For more
information on BPL, visit the "Broadband Over Power Line (BPL) and Amateur Radio"
page on the ARRL Web site. To support the League's efforts in this area, visit
the ARRL's secure BPL Web site.
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