ARRL

ARRL General Bulletin ARLB032 (2004)

SB QST @ ARL $ARLB032
ARLB032 FCC BPL Report And Order stresses interference avoidance,
resolution

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ARRL Bulletin 32  ARLB032
From ARRL Headquarters  
Newington CT  October 29, 2004
To all radio amateurs 

SB QST ARL ARLB032
ARLB032 FCC BPL Report And Order stresses interference avoidance,
resolution

The FCC has released the full BPL Report and Order (R&O) in ET
Docket 04-37 that it adopted just two weeks ago. While extolling the
purported benefits of broadband over power line technology, the
81-page document also declares the FCC's intention to "protect
licensed services from harmful interference."

"We recognize that some radio operations in the bands being used for
Access BPL, such as those of Amateur Radio licensees, may occur at
distances sufficiently close to power lines as to make harmful
interference a possibility," the FCC conceded. "We believe that
those situations can be addressed through interference avoidance
techniques by the Access BPL provider such as frequency band
selection, notching, or judicious device placement."

Notches would have to be at least 20 dB below applicable Part 15
limits on HF and at least 10 dB below on VHF. The FCC called the
ability to alter a system's operation to notch out transmissions on
specific frequencies where interference is occurring "a necessary
feature for resolving interference without disrupting service to BPL
subscribers."

The FCC declined to reduce the Part 15 radiated emission limit for
BPL systems. It maintained that emissions from BPL systems are very
localized and at low enough levels to generally preclude harmful
interference.

The FCC said while it had no evidence before it that BPL operation
would significantly contribute to background noise levels, it seemed
to put some of the onus on Amateur Radio licensees to take steps to
avoid power-line interference--and, by inference, BPL
interference--in advance.

"In addition, because power lines inherently can radiate significant
noise emissions as noted by NTIA and ARRL, good engineering practice
is to locate sensitive receiver antennas as far as practicable from
power lines," the FCC said.

In a footnote, the FCC admonished ARRL that in cases where its
members experience RF noise, "such noise can often be avoided by
carefully locating their antennas; in many instances an antenna
relocation of only a relatively short distance can resolve noise
interference."

BPL operators would be required to avoid certain bands, such as
those used for life and safety communications by aeronautical mobile
or US Coast Guard stations. The FCC R&O makes clear, however, that
similar rules will not apply to the Amateur Service.

"We similarly do not find that Amateur Radio frequencies warrant the
special protection afforded frequencies reserved for international
aeronautical and maritime safety operations," the Commission said.
"While we recognize that amateurs may on occasion assist in
providing emergency communications," the FCC added. It described
typical amateur operations as "routine communications and hobby
activities."

The Commission reiterated its belief that BPL's public benefits "are
sufficiently important and significant so as to outweigh the limited
potential for increased harmful interference that may arise."

Among other specific provisions, the FCC's new rules mandate
certification of BPL equipment instead of the less-stringent
verification, a public BPL database--something the BPL industry did
not want--and mechanisms to deal swiftly with interference
complaints. BPL systems will have to incorporate the ability to
modify operation and performance "to mitigate or avoid potential
harmful interference" and to deactivate problematic units, the R&O
says.

Further, the new rules spell out the locations of "small geographic
exclusion zones" as well as excluded bands or
frequencies--concessions made primarily at the insistence of the
NTIA, which administers radio spectrum for federal government
users--and "coordination areas" where BPL deployments at any
frequency must be "precoordinated by BPL operators." They also
detail techniques to measure BPL emissions from system equipment and
power lines.

The FCC said it expects "good faith" on both sides in the event of
interference complaints. Shutting down a BPL system in response to a
valid interference complaint "would be a last resort when all other
efforts to satisfactorily reduce interference have failed," the FCC
said.

ARRL officials are studying the R&O and considering possible
responses. The ARRL Executive Committee (EC) already has authorized
filing a Petition for Reconsideration. The EC also authorized ARRL
General Counsel Chris Imlay, W3KD, to "prepare to pursue other
available remedies as to procedural and substantive defects" in the
BPL proceeding.

For more information on BPL, visit the "Broadband Over Power Line
(BPL) and Amateur Radio" page at,
http://www.arrl.org/tis/info/HTML/plc/.
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