[SOC] FW: [cq-l] NTIA Reports on BPL Interference Study

Thu Apr 29 08:59:46 2004

FYI

73 de N8AU, Jim in Raymore, MO

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From: [email protected] =
[mailto:[email protected]] On Behalf Of =
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Sent: Wednesday, April 28, 2004 2:55 PM
To: [email protected]
Subject: [cq-l] NTIA Reports on BPL Interference Study

>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:=A0=A0 "(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=A0 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=A0 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=A0 =
some not mentioned in the NPRM=A0 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.=20

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