[HCRA] Fw: [emergcomm] Digest Number 787
[email protected]
[email protected]
Mon, 19 May 2003 08:35:41 -0400
Some interesting reading in the second article.
Eric Tuller N1QKO
flash floods+warlords+winter storms+callisto+tornados
WHEN ALL ELSE FAILS.....AMATEUR RADIO !!
earthquakes+monsters+hurricanes+evil gods+public service
CT+ MD+ VT+ King Richards Ren Faires
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Date: 19 May 2003 08:52:05 -0000
Subject: [emergcomm] Digest Number 787
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There are 2 messages in this issue.
Topics in this digest:
1. Reminder - Oakville REACT Executive Meeting
From: emergcomm
2. Sounds Ominous... FCC Broadband over Power Lines
From: "Rick Harrison" <[email protected]>
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Message: 1
Date: 18 May 2003 23:32:28 -0000
From: emergcomm
Subject: Reminder - Oakville REACT Executive Meeting
We would like to remind you of this upcoming event.
Oakville REACT Executive Meeting
Date: Wednesday, May 21, 2003
Time: 7:30PM - 9:30PM EDT (GMT-04:00)
In the United Way boardroom, 466 Speers Rd. Suite 200, Oakville,
Ontario.
________________________________________________________________________
________________________________________________________________________
Message: 2
Date: Mon, 19 May 2003 00:22:19 -0400
From: "Rick Harrison" <[email protected]>
Subject: Sounds Ominous... FCC Broadband over Power Lines
Borrowed from another list.
----- Original Message -----
Thought the SARA, SVHFSociety, and RadioJove list-servers might be
a
good place to mention something currently making the rounds as a hot
topic
for comment to the FCC. This FCC Docket No.03-104 for using the nation's
power lines for data communications is the subject of my "President's
Page"
editorial letter in the upcoming SARA Journal. But with the comment
period
ending in mid June many might not have a chance to read about it and
research it on the Internet in time. So I'm including the article and
some
hyperlinks below.
Its also the subject of the June 2003 QST "It Seems to Us.."
Editorial
now hitting our mailboxes. After all, whenever anyone has TV
interference..
who gets blamed? The neighbor with the big antenna. This may really stir
up
a hornet's nest of trouble like none we've ever seen, with innocent hams
taking the blame for Broadband Internet services the neighbors themselves
unwittingly purchase.
One thing I've found out since writing this is that the frequency
range
for the primary modulation involved is a bit higher than I allude to
below.
Its design frequency range is 2-80 MHz. And this is more than just "last
mile" infrastructure. They're talking about also using this on much of
the
distribution side of the power grid, as in substation to home. Do some
reading. A search on "Broadband over Power Line" already catches almost a
thousand hits, and its growing fast.
Sounds like a real coast to coast RF noise and interference
generator.
But with changes in FCC... the attitude seems to be "So?". Have a look.
Most
of us who've done RF design, hams or not, are both afraid, and
incredulous,
that this kind of thing could ever get to this stage of discussion.
Regards,
Charles S. Osborne, K4CSO
Society of Amateur Radio Astronomers, President
Technical Director
Pisgah Astronomical Research Institute
1 PARI Drive, HC 73, Box 638
Rosman, NC 28772-9614
http://www.pari.edu
828-862-5813 direct
828-862-5554 main
828-862-5877 FAX
[email protected]
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--
Broadband Over Power Lines (BPL)
This month's hot topic is an FCC Notice of Inquiry called
"Broadband Over Power Lines" [FCC ET Docket No.03-104]. Most of the time
I
ignore FCC NOI and NPRM (Notices of Proposed Rule Making) that are
clearly
going to generate a maelstrom of negative comments. They usually
disappear
for six months and get reintroduced after radical changes. But let's not
trust that to happen in this case. See
http://www.arrl.org/news/stories/2003/04/30/2 for further info on how to
file comments with the FCC electronically.
You see the FCC has touted BPL as a potential way to get
high
speed Internet to the masses. Cable-TV and DSL are only available to
citizens located close to cities and high speed points of presence for
the
phone company. But everyone has AC power lines. So the FCC thinks this
will
be the answer to getting the Internet to more people who are still on
slow
speed dial-up. Politically this sounds great. Technically it has ominous
implications. Early tests indicate it could raise the noise floor +30 dB
above galactic background at HF. You won't be doing much JOVE / Solar
20MHz
work, or even regular ham radio under those conditions. The chances for
regular ham radio stations to interfere backwards into such a network is
also enormous.
One overlooked problem is feeding the bandwidth into your
area.
Every transformer constitutes a block to high speed signals. So somewhere
close to the end users, even higher bandwidth needs to be available to be
divided out. Sounds like a job for fiber. Yet the locales that this is
really targeting probably don't have fiber or they'd have DSL. This may
be
yet another idea that works at small scales, but becomes a real mess,
system
engineering wise, when widely deployed. Give it ten years, and 2.4 GHz
wireless could also be an example of that.
Ever walked by your PC monitor and picked up buzzing
interference on a ham handie talkie, scanner, or AM radio? Monitors have
steadily become faster and higher bandwidth devices themselves. But as
their
bandwidths passed 100 MHz the SVGA cables started looking like good
antennas. Ferrite beads on the cords today help make them pass FCC
Part-15
emission specifications.
But what if the antennas become power lines, distributed
over
your whole neighborhood via everyone's AC wiring? The local pole to house
wiring could look like a pretty good HF antenna. Anything more than a
tenth
wavelength or with significant VSWR will start to radiate signal. This is
very obvious to those of us who have designed RF circuit boards, finding
that compact circuits, matched impedances, and ground planes for
shielding
are needed to keep the signals from jumping from one trace to another or
radiating. Aside from using all underground wiring to get to the house,
there's very little we can do to stop a 1 MHz or 10 MHz signal from
radiating from house wiring. In fact there are significant regulations on
computers and appliances to keep them from radiating back out into that
same
AC wiring at low frequencies.
In an odd twist the FCC turned down a request to create a
new
ham band at 136 kHz due to pressure from the power utilities who already
use
VLF to send control and monitoring signals between high tension line
substations over the powerlines. The utilities were afraid that a few
hundred 50watt ham stations scattered across the country would interfere
with their substation controls. Guess they weren't consulted about BPL.
With
millions of potential interferers coast to coast, once they figure this
out
the utilities will likely also be on the FCC's back for even proposing
the
idea.
Cable TV systems constantly fight broken shields,
unterminated
lines, or poorly crimped F connectors turning the cable into an antenna.
When this happens, FAA airport approach frequencies, and local television
stations are jammed by the cable system signals on those frequencies.
With
BPL the AM radio band could easily become unusable for over the air
reception of all but the strongest signals.
Digital signals are insidious for making harmonics. A 48
MHz
PC
clock crystal can easily be received all the way to 10 GHz and beyond. So
what's to make the BPL low frequency signals and all their harmonics stay
on
unshielded wire? There are products out there specifically made to use
house
wiring as a hidden ham HF antenna. In the case of BPL, by some mystery
the
FCC thinks it will not cause harmonics and excessive radiated
interference.
Tests show significant effects even in the 327 MHz radio astronomy
frequencies.
The evaluation tests on typical house wiring indicate that
one
would have to be 219 km away to drop below the ITU-R RA769-1 recommended
signal levels in the radio astronomy bands at HF. House wiring looks
like
a -30 dBi antenna. Worse, if everyone in your neighborhood is on this
system, the noise power from many sources will add. The overall effect
the
FCC is shooting for is that everyone's noise floor gets degraded just a
little. But with radio astronomy being down in the -200 dBm range, the
desired to undesired signal to noise ratio will be at a disadvantage.
I'm hoping some of you will send comments to the FCC in
response to this NOI. Do not call them idiots, or make irrational "You
can't
do
this!" statements. They are the FCC. They can do it, with a simple stroke
of the pen. Arguments saying it will violate Part-15 limits have been met
with FCC comments like "Well, we'll change part 15." So expect anything
that
provides: "economic stimulus", "looks good politically" to the most
constituents, and adds "competition" to the market place to get a speedy
route through the regulatory process. We have until mid June for your
well
thought out, cleverly articulated comments to reach the FCC.
Charles Osborne, K4CSO, SARA President
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Links:
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-03-100A1.pdf
http://www.arrl.org/tis/info/HTML/plc/
http://www.computerworld.com/printthis/2003/0,4814,80616,00.html
http://www.computeruser.com/news/03/04/25/news5.html
http://www.southern-telecom.com/pr08072002.asp
http://www.eweek.com/print_article/0,3668,a=40772,00.asp
http://www.gsblaw.com/practice/practice.asp?ID=21
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