[South Florida DX Association] Fw: [cq-l] NTIA Reports on BPL Interference Study]

[Tom Lewis]

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Subject [cq-l] NTIA Reports on BPL Interference Study
04/28/2004 03:54 PM


Please respond to w2vu


 From the CQ Newsroom:

The National Telecommunications and Information Administration (NTIA)
has issued its long-awaited report on the interference potential of
Broadband over Power Lines (BPL). Despite a generally-glowing news
release, the report itself identifies significant interference risks
from BPL and concludes that the methods currently used for measuring BPL
noise levels are inadequate and that more study is needed on such areas
as ionospheric propagation of BPL signals.

The full report may be downloaded, either in full or chapter by chapter,
from the NTIA website at: <http://www.ntia.doc.gov/new.html>. Our
summary of the report's major findings follow.

CQ Summary of NTIA report to the FCC on BPL:

NTIA concluded…
1) …that the methods currently used to measure noise levels and
interference potential are inadequate:   “(A)pplication of existing Part
15 measurement procedures for BPL systems results in a significant
underestimation of peak field strength. Underestimation of the actual
peak field strength is the leading contributor to high interference
risks. As applied in current practice to BPL systems, Part 15
measurement guidelines to not address unique physical and
electromagnetic characteristics of BPL radiated emissions.” (Executive
Summary)

2) … that noise levels must be measured from BPL-energized power lines
as well as the “device” coupling the signal to the power lines: “BPL
systems generate the highest electric field strength near the BPL device
for horizontal-parallel polarized signals. However, these systems
generate peak vertically-polarized field strength under and adjacent to
the power lines and at impedance discontinuities at substantial
distances from the BPL device.” (Executive Summary)

3) … that interference to weak-to-medium strength signals is likely out
to 460 meters (1500 feet; more than 1/4 mile) from a BPL noise source at
ground level  and out to a 40-kilometer (25 mile) radius from the signal
source for an airplane at an altitude of up to 6 kilometers (approx.
20,000 feet): “Interference to land vehicle, boat, and fixed stations
receiving moderate-to-strong  radio signals is likely in areas extending
to 30 meters, 55 meters, and 230 meters, respectively, from one BPL
device and the power lines to which it is connected. With
low-to-moderate desired signal levels, interference is likely at these
receivers within areas extending to 75 meters, 100 meters and 460 meters
from the power lines … (I)nterference to aircraft reception of
moderate-to-strong radio signals is likely to occur below 6 km altitude
within 12 km center of the BPL deployment. Interference likely would
occur to aircraft reception of weak-to-moderate radio signals within 40
miles of the center of the BPL deployment area. (Executive Summary)

4) … that results of BPL tests and implementations in other countries
have been mixed: “BPL apparently has been implemented with success in
some countries, while other countries have postponed implementation of
BPL systems until further interference studies are … conducted. Still
others have withdrawn their approval for operation of BPL systems after
experiencing interference problems.” (Section 9, Summary of Results).
One example cited was that “(d)uring an emergency exercise of the
Austrian Red Cross in May 2003, communication was massively disturbed by
(BPL), with interference levels exceeding the limits by a factor of
10,000.” (Appendix B)

5) … that more study is needed in several important areas, including
skywave propagation of BPL signals, that it will conduct further studies
and issue a report later this year: “NTIA will complete a Phase 2 study
later this year that will assess the potential interference risks due to
aggregation and ionospheric propagation of interfering signals from BPL
systems; refine and apply BPL deployment models; and evaluate the
effectiveness of proposed Part 15 measurement techniques.” (NTIA News
Release)

NTIA is recommending more stringent measurement standards and
procedures, along with several interference mitigation techniques  some
not mentioned in the NPRM  although it admitted that the nature of power
lines and of BPL would limit the effectiveness of some of them.
Additional recommendations are likely after the second phase of the NTIA
study is completed later this year. Acting NTIA Administrator Michael
Gallagher called the NTIA recommendations “the technical foundation for
the responsible deployment of broadband over power lines.”

CQ Opinion: It is clear from the results of the NTIA study that the
FCC’s rulemaking proposal is premature at best, and it would be
irresponsible of the FCC to go forward in enacting BPL rules before the
NTIA Phase 2 study is completed later this year.

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