I've worked with Mike before on power line noise locating. Tell him I
said "Hi" if you see him later.
I'm curious, how would he know that BPL was "in use" while he was
driving around? If you aren't hearing anything and it's a main.net
system, that can also mean that no one is actively using a modem on the
system.
We just tested a Generation One Main.net BPL system here with only 5
possible users on it. With no one actively using the system, the system
is in idle mode and is indeed VERY QUIET. There's only a very faint
clicking for each modem, so with only a few modems you might not hear
them unless you stood directly beneath the power line like I did.
BUT, the minute you start using the internet and downloading files like
MPEG or WAV files, the noise starts. It sounds just like power line
noise so I'm sure Mike will be able to recognize that when he hears it!
;-) Without any notching it was VERY STRONG (s9+) in a mobile parked in
the street in front of the house using an antenna not tuned for the band
we were listening on. With notching, it was still moderately strong
(s2-5) .
Initially the utility's BPL consultant tried to convince us that he was
simulating loading by sending 200 byte packets every 50 msec was loading
the system at 60% or more. The system has a 1.536 Mbps (single T1) max
capacity as installed. Perhaps my math's rusty, but 200 bytes should be
1600 bits every 50 msec; this gives 32000bps. Percentage loading would
only be 2.1% on my calculator.
Even with the system downloading files, they admitted there's a 300Kbps
cap/limit of each user. That's 20% MAX with only one active user. The
signal levels above were for this level of loading which is really
broadband by today's definition.
So the point of all of this is the BPL folks can pull a fast one on you
if you let them. If you're going to participate in any of these trials
and make such reports, get educated what "wool" looks like so when they
pull it over your eyes you'll be able to "see" what's really happening.
For more info, join the BPLandHamRadio reflector on yahoogroups. If you
have a trial in your area and you're local club has a BPL committee,
contact Ed Hare at ARRL and ask about getting more detailed information
on other trials.
73,
de ed -K0iL
-----Original Message-----
From: rfi On Behalf Of Alan NV8A (ex. AB2OS)
A group of us met last night with Mike Martin K3RFI, who is an
interference investigator by profession (he was in town for
consultations with the Holland Board of Public Works, which ran
fiber-optic cable through the whole business district years ago and has
not the slightest interest in doing BPL) and often helps other hams with
RFI issues.
He said that he has driven through areas where BPL is in use, but with
his sophisticated and expensive equipment has never detected anything
other than the normal power-line noise to be found anywhere.
FWIW.
Alan NV8A
On 10/22/04 01:37 pm EDWARDS, EDDIE J put fingers to keyboard and
launched the following message into cyberspace:
> Once BPL is installed in enough cities you will have to have an amp if
> you want to be heard above the new noise floor; otherwise no one will
> hear you calling even if you don't have BPL in your area.
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