I find it amazing as well that Utilities think that there will be a day
that when interference is detected, it will move channels automatically.
In other words, when a ham fires up on say, 20 M, it will move to protect
that frequency band. All of this depends on someone transmitting a signal
first, before the interferring BPL signal moves to another channel. So for
the casual tuning of the band, without transmitting, expect the
interference to continue. First, I can even imagine such an intelligent
system that would do this on a transformer by transformer basis. Rather
cost prohibitive I would say for the BPL vendors, not to mention at what
level of signal reduction would you actually see? 30 dB down, 60 dB? or
would it just completely vacate the 20 M band? And when would the noise
reappear, after say 5 minutes, 3 days or ? I have been told that if 4
channels are dropped from the 80 channels possible with BPL, the throughput
is still very good and protects the ham bands. Not sure how true that
statement is - both from an interference perspective or from the throughput
point of view.
Apparently there are ways to notch out the ham bands with certain BPL
vendor supplied hardware, using software, but I can't imagine how much real
rejection is possible. Is 20 dB or 40 dB enough to protect you from that
transformer-located, BPL system at the end of your road? Can someone do
the testing that KB9CRY is suggesting at locations where Amperion or
Main.net have supplied equipment? Rumor has it Main.Net is the better,
more agile system over Amperion. The Pan Yen installation in NY is built
on Amperion where the Manassas, VA site is built with Main.Net. I have
heard the mpg file made by the Rochester VHF club of the Pen Yan site,
very bad. What are the Manassas folks saying from the Ham community? Has
anyone recorded any examples from this location? Assume Ed Hare from the
ARRL has got some details here.
Regards,
Mark, K1RX
kb9cry@comcast.net@contesting.com on 04/26/2004 11:20:24 AM
Sent by: towertalk-bounces@contesting.com
To: towertalk@contesting.com
cc: antenna-discussion@antennex.com
Subject: Re: [TowerTalk] BPL article.... amazing....!!!
I haven't yet submitted my comments but I'd like to point out one flaw in
all of this BPL discussion and "testing" that is being performed. Let me
quote from the original article mentioned in this thread:
"While the radiation from the power lines will be real, I suspect the
signal level to be pretty low."
"The FCC says that there may be some interference.."
"If a ham's station and antenna are
close to the power lines, there may be some interference. How many
hams will be impacted? Hard to say, but probably not many."
"Not really, simply because the Part 15 radiation levels
are so strict. I predict that the same will occur with BPL."
If you read carefully through these lines and the FCC's NPRM and other BPL
comments by BPL providers you will see a common theme. Everyone is
believing or predicting or suppossing but no one, even the FCC, is
stating anything. The following rant will be the basis of my NPRM
comments. Last time I went to a physics class, electro magnetic theories
were proven scientific facts that could be predicted and measured. How
many of these BPL test do you see a BPL network put into service and then
the BPL provider just waits for complaints. If no complaints come forth,
then the test is deemed a success and interference is deemed to not exist
nor be harmful. How un-scientific (or is that non-scientific) testing is
that. The BPL testers can obtain HF receivers or even use a spectrum
analyzer to measure for themselves the degree and levels of interference.
And, I think that the FCC should mandate that this be done by the BPL
providers. If properly designed and executed scientific
testing was performed then BPL providers as well as the FCC can then say
"We know..." rather than theorizing. This is a science not a religion.
One can actually have proof. Phil KB9CRY
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|