On Thu, 16 Oct 2003 16:00:39 GMT, Dave Shrader
wrote:

Look at that BPL antenna in the foreground!!!!
That's nearly half a mile away and probably not the type of lines
they'd be using. I think they need their feed points closer together
than those towers.

So far I get very little noise from that line, but the one feeding the
neighborhood comes in from the south through a mile of woods. It has
some very noise spots, but of the intermittent variety.



Roger Halstead wrote:

On Wed, 15 Oct 2003 20:20:31 GMT, "Jim Hampton"
wrote:


Brian,

I don't know about you, but I received a whole week pass from Belleveu

I'm not sure about the crazy part, but...
For those who have a "good" broadband connection here is a panoramic
view from the top of my tower. If you don't have broad band, don't
waste your time. This thing is 19.5 megs. It should take under a
minute with cable, and close to 10 minutes with ADSL, so you can
imagine how long it'd take with a dial up connection.
http://www.rogerhalstead.com/towerview.htm
I stood on the triangular top plate of the ROHN 45 G (at 100 feet) and
shot the entire series hand held. The camera was set to manual, but

BTW, I was thoroughly belted to the mast coming out the top of the
tower. Where I was standing the mast is really two concentric steel
tubes. One is 1 1/2 while the other is 2 inch. Both have 1/4 inch
wall. There are two 21 foot lengths of 1 1/2 welded together and then
a single two inch, 21 feet long over the middle.

I put all that up by hand and welded the two center masts together
inside the tower.

the wind was gusting to 20 MPH plus, so a few of them didn't line up
good enough for a proper match when making the panorama.

20 MPH gusts make all that steel shift around while the tower hardly
quivers. When the wind gets up around 60 to 70 MPH the top of the
mast with the pair of 12L 2 meter antennas and a pari of 11L 440s
looks like a Bluegill fly rod that just hooked into a Largemouth Bass.
It's amazing those two arrays have held together this long.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

On 15 Oct 2003 22:30:17 -0700, Brian Kelly wrote:

This means that the manufacturer is required to test them to
ensure that they comply with the FCC regulations. Under the present
rules, they must be tested at 3 typical locations. "

What's the FCC definition of "typical locations"??

De facto: any place where the results support the stand that one is
advocating.

--
73 de K2ASP - Phil Kane

Yeah Roger, I used to live within 100 meters of three sets of 3 phase
high tension lines and they were VERY quiet. In 38 years of operation
from that location I can't recall more than a handful of noisy times,
generally during high humidity in July/August, when the insulators would
corona. These were generally cleaned up within a few days to a week.

DD, W1MCE

Roger Halstead wrote:

Is the ARRL preparing a FAQ for amateurs who have scopes, spectrum
analyzers, or service monitors, etc., as to how they might go about
inspecting a suspected chunk of spectrum and how detect, identify,
qualify whey they see/hear?

Not at this time, Dan. I want to talk with amateurs who are going to go into
the trial areas, to share my experiences and to make sure I learn as much as
possible from theirs. FAQs are a great way for beginners to learn about a
subject, but some things are still best left to real dialogue.

73,
Ed Hare, W1RFI

I think a general description of other RFI sources would be helpful for any
radio amateur to make a 'first cut' assessment. It might also help you
isolate
the truly legitimate cases of BPL RFI--if and when they exist.

There are several RFI sources that would be the most common ones misidentified
as BPL. The first is "conventional" power-line noise. It is usually
characterized by having a *noisy* 120-Hz component, as the sparking takes place
on the positive and negative peaks of the 60-Hz wave. Another is similar,
occurring from things like lamp dimmers, motor controllers, flourescent lights,
etc. Those sources usually have a 120- or 60-Hz component, but the noise on the
peaks is usually quite a bit less noisy looking.

Switch-mode power supplies can also be noisy, but they generally have noise
that ranges from reasonably coherent (carrier-like) to broad, buzzy clumps of
noise, spaced every N kHz, where N is the free-running rate of the switcher
frequency. N is typically 10-50 kHz or so. Some switchers make noise that is
fairly close to gaussian-distributed noise, with a pretty uniform
distibribution of power vs frequency (power spectral density). One key
diagnostic for a switcher is that the N kHz tends to drift around a bit. A
series of noisy carriers or clumps of noise that are spaced every 15 kHz, for
example, may drift up the band as the unit is turned on and warms up over an
hour or so. If so, it is almost certainly a switcher.

(I do, btw, suspect that the "plasma tv" problem is really a switch-mode
problem, as some amateurs have reported no interference from plasma TVs. On my
long list of things to do is to take the Lab's Icom R-3 receiver to the local
big electronics store and see if I can get some estimates of the noise level
from various equipments.)

Probably the most diagnostic, however, it the distribution of noise signal vs
frequency. BPL is designed to use specific spectrum, and as one tunes a general
coverage receiver from 2 to 80 MHz, its onset will be rather sudden, it will
persist for at least several MHz, then taper off just as abruptly.

I do have a concern that hams not make too many false alarms. Sounds like you
are on top of the the problem and I wish you the best.

There are no guarantees, but I am hoping that by talking to each of the hams
that report BPL interference, between them and me we can reach the correct
conclusion. If things don't add up, I will suggest that it not be reported.
Each report of actual interference is precious right now, and I would be
willing to go to the trial area to verify a questionable case.

Thanks for your interest.

73,
Ed Hare, W1RFI

TV channels 2, 3, 4, and 5 will get clobbered by the junk going up to 80MHz.
The video signal is AM modulated onto the channel carrier (with a
portion of the
lower sideband suppressed) and will have no ability to reject the BPL
noise.
The effect would be somewhat similar to a sparky vacuum cleaner motor
throwing
white and black spots throuout the picture. The sound, being FM, will fare
better. Well, there's digital HDTV, but most everyone still uses analog TV.
And I don't get cable or satellite.

2 to 80 MHz is the spectrum that the BPL folks asked to try in their
experimental license applications. I have not seen any BPL above 50 MHz -- so
far.

And at the levels I have seen BPL, digital TV won't help. The digital TV
demodulation process can ignore noise up to a point. An analog TV signal that
was somewhat noisy, but perfectly watchable, would probably be clean on
digital. An analog signal that was noisy, but still just watchable would have
many digital errors that would result in portions of the screen locking up for
a few seconds at a time, loss of audio for seconds, etc. And just a little bit
past that point, the digital TV signal would fall apart all together.

73,
Ed Hare, W1RFI

Under the present
rules, they must be tested at 3 typical locations. "

What's the FCC definition of "typical locations"??

There is none.

15.209 is the problem, it's grossly outdated, did not foresee anything
like BPL and the limits needs to be revised downward which is one
piece of this brawl. Ref: Tailpipe emissions regs, same basic problem,
different pollution media.

A good tailpipe analogy would be to consider the present tailpipe emissions
limits. We can still breathe with the number of cars that emit. Now, the
equivalent to BPL emissions occurring on several MHz at a time would be to
stack 100 cars on top of each other and have them all running at the same time.
The equivalent to building the system as large as an entire community is to do
that for every square inch of roadway. Would the emissions limits that work for
an occasional car passing by your home still work under those circumstances, or
would we all choke to death in a matter of minutes?

73,
Ed Hare, W1RFI

"Phil Kane" wrote in message . net...
On 15 Oct 2003 22:30:17 -0700, Brian Kelly wrote:

This means that the manufacturer is required to test them to
ensure that they comply with the FCC regulations. Under the present
rules, they must be tested at 3 typical locations. "

What's the FCC definition of "typical locations"??

De facto: any place where the results support the stand that one is
advocating.

Oh golly, I would never have guessed that . .

http://www.rochesterdandc.com/biznew...business.shtml

Not a lot of hard info here, but politics in action.

On 17 Oct 2003 11:28:37 GMT, (W1RFI) wrote:

snip

Switch-mode power supplies can also be noisy, but they generally have noise
that ranges from reasonably coherent (carrier-like) to broad, buzzy clumps of
noise, spaced every N kHz, where N is the free-running rate of the switcher
frequency. N is typically 10-50 kHz or so. Some switchers make noise that is
fairly close to gaussian-distributed noise, with a pretty uniform
distibribution of power vs frequency (power spectral density). One key
diagnostic for a switcher is that the N kHz tends to drift around a bit. A
series of noisy carriers or clumps of noise that are spaced every 15 kHz, for
example, may drift up the band as the unit is turned on and warms up over an
hour or so. If so, it is almost certainly a switcher.

Watch out for Silicon Controlled Rectifiers (SCRs) used for power
switching. They switch on the during a portion of the positive
swinging cycle generating a *sometimes* huge pulse and are usually
used in pairs. They are always 60 cycle, but as there is one on each
polarity there will be two equally spaced pulses appearing as if they
were a single 120 cycle repetition. OTOH a 3-phase system might look
a bit confusing. However the pulse train "should" be symmetrical
based on 120 degree spacing of a 60 cycle base which might give the
appearance of 180 cps. These things are bad enough that the pulses
from one system can cause false triggering in another SCR system
nearby.

snip

Precip static and in particular, snow static does a very good job of
imitating the sound of some bpl, *but* it looks entirely different
when seen as a time domain display. The static will be a display of
relatively evenly spaced pulses that will *usually* increase in
frequency over time. A single unterminated half wave 75 meter dipole
can blank out a whole city block on some frequencies. The voltages
generated can make the ignition coil in a car look puny.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

snip

Thanks for your interest.

73,
Ed Hare, W1RFI