[RFI] Noise Locator (sorta long)
EDWARDS, EDDIE J
EDWARDS, EDDIE J" <eedwards@oppd.com
Mon, 8 Nov 1999 09:29:01 -0600
> -----Original Message-----
> From: Larry Burke WI5A [SMTP:lburke@wt.net]
> What is considered to be the state-of-the art instrument for locating
> noise
> sources such as faulty pole line hardware, fluorescent lamps, neon signs,
> door bell transformers, etc? Lately the portable AM/FM radio isn't
> cutting
> it as a detector and the power company had to dust off their
> turn-of-the-century box when they came out. Is there something more
> sophisticated... particularly something that can be rented from an
> instrument rental outfit?
> Larry WI5A
>
[Ed-K0iL] Hi Larry,
You probably won't find this stuff at the local instrument rental
place. There's not much demand for it out there now that Television is
almost always on RG59 or RG6 instead of wireless. And almost no one listens
to AM radio anymore, except Rush Limbaugh fans. Power companies just don't
get many calls anymore on power line noise except from us pesky Hams!
Here's some info I've sent to this reflector in the past on locating power
line noise & the equipment needed:
"Tearing my hair out", Tom Hellem- K0SN wrote:
>Wondering if anybody has experience locating noise generated by power
>lines?
>The power company has been out here at least 5 times, and they claim they
>have checked out a 10 mile radius. As far as they are concerned, the case
is
>closed and they have refused to do anything further.
You've discovered another impact of the FCC's non-enforcement of
interference
rules, but this time it is us hams who are experiencing the interference.
So
now how do we determine which pole is causing your specific interference
problem?
Well, I'm no guru in this area, but I have gained some experience over the
last few years working in my Power Company's Communications Dept. where we
are
assigned the task of resolving RFI complaints. The key is having the proper
equipment to conduct the search. In some cases it takes more than one type
of
location device to complete the search correctly. And it also takes an
experienced locator to determine the source of your interference among the
many sources he will find out there. Hopefully your power company has
these
resources! If not, gently suggest that they get them ASAP to solve your
problem.
First, the equipment. A radio receiver(s) capable of multi-band operation
from HF & VHF thru UHF. This can be two or three different radios if
needed.
Many companies use a locator on just one frequency (like 200MHz). But to
properly track down the source, multi-band operation is a must.
Another device that can help determine which pole is the source and which
are
just re-radiating the RF noise is a ultrasonic probe. UE Systems in
Elmsford,
NY sells one fitted with a parabolic dish concentrator (UWC-2000). I have
used this unit at work, and was able not only to determine which pole was
the
source of noise but also determined from the base of the pole what piece of
hardware was the specific source! (e.g. squirrel guard) BTW: This solved
the
noise problem near my ham shack ;^) UE Systems' phone number is
800-223-1325. (Std disclaimer: Not associated in any way. Just a satisfied
customer).
Another interesting device I haven't used yet is a combination broadband
receiver, spectrum analyzer and storage scope made by Radar Engineers in
Portland, Oregon (503)256-3417). What is interesting about this unit is the
storage scope function. Its receiver is tunable from 1.8 - 1000 MHz. The
operation is to hook it up to the customer's antenna and tune to the problem
frequency. The waveform of the noise can then be viewed and saved in memory
for comparison while searching in the field for that specific noise. It
comes
with a 10 element VHF/UHF log periodic antenna. This sounds like the ideal
RFI locator to me! I wish we had one. :^(
There are also a couple books to recommend to your utility if they don't
already have them. I recommend them both to any ham who has a line noise
problem. Both were written by hams who worked for utilities as RFI
Investigators. The first one I recommend is *Interference Handbook* by
William R. Nelson, WA6FQG & edited by Bill Orr, W6SAI. It sells in both CQ
magazine & ARRL bookstores. This is the "Bible" of power line noise
location.
I've read it cover to cover and refer to it often.
Another one is *AC Power Interference Manual* by Marv Loftness, KB7KK. Marv
is big on the Radar Engineers line of equipment. As a matter of fact, they
even sell his book! It is published by Percival Publishing in Tumwater, WA.
I
haven't made it through this book yet, but it looks pretty good.
One thing to remember: Ultrasonics can only be detected line of sight at
close
range. That's how they work. It will help to eliminate poles that are not
noisy. But it will not identify the source of YOUR specific noisy pole
without an experienced investigator or additional equipment. If you get
them
to start fixing noisy poles that are NOT causing your specific problem, they
may get tired of doing this before getting to your problem source. It can
get
very frustrating! Hang in there!
If your power company refuses to respond to any further requests, contact
your
state's public service commission (PSC) in writing concerning your problem
and
lack of response. Sometimes just mentioning this to the utility will get
them
off their duff! If they've sent the same technician out all five times,
then
they have not made an honest effort to solve the problem. You can find info
on your state's PSC on the ARRL web I think under the Technical Information
Services.
You can also download some good stuff from ARRL from their
info-server [info@arrl.net] by sending a message with the following in the
body:
SEND INDEX
SEND RFI-ELEC
QUIT
The first will send you a message with the complete info-server
index (in 2 parts). The second will send the electrical line noise info
(also 2 parts).
Here's another one of my msgs that dealt with the same subject.
There's a little duplication.
-----Original Message-----
From: EDWARDS, EDDIE J [SMTP:eedwards@ep.oppd.com]
Sent: Thursday, 01 October, 1998 4:38 PM
To: rfi@contesting.com
Subject: RE: [RFI] Tracking the Noise
Carlos PT2HO (also PY1CAS) wrote:
> I have a problem of constant noise in my reception on all bands, it is
> like
> an increase of the static level. The noise looks to be man made and
> when it
> rains the noise disappears.
> My question: how can I track this noise source?....As you know Brazil
> is an
> emerging country and the Power Company notified me that they won´t
> provide
> any kind of help. Any ideas?? I have a portable shortwave
> transceiver.....Does it help??
> I need to solve this problem by myself. The Eletricity Agengy and the
> Power
> Co. will not help me at all.
>
[K0iL] Are you saying the power company will not find the noise
for you, or they won't even correct the cause of the problem once you
find it? I hope it is only the first situation, otherwise you're SOL
(out of luck).
You'll need to learn allot about power lines and associated
hardware. I recommend the "Interference Handbook" by William R. Nelson,
WA6FQG sold by ARRL and CQ magazines. I don't know how much hardware
specific info in the book will apply to you in Brazil, but the info on
how to search will definitely be helpful. While your waiting for the
book to show up you can start searching for the noise with your portable
rcvr. It would really help to have a hand-held VHF yagi and VHF AM rcvr
to conduct your search and narrow in on the dirty pole.
First make sure it's not something in your own house. Kill the
main breaker feed and listen on the portable radio. No noise? Start
looking inside the house by opening only one breaker at a time to see if
it goes away. Once you've determined what circuit it's on, start
unplugging anything on that circuit one at a time. If the noise is not
inside the house go, start your search outside.
Start the search by listening on the portable rcvr (on AM) at
low freqs like about 1-2 MHz (AM broadcast band is good). Walk around
your block and neighborhood (maybe even drive around) while listening on
the low freqs. Note where the noise is strong then starts getting
weaker. This indicates you are going away from the noise. But watch
out for standing waves along power lines conducting the noise. It may
get better at one pole only to get worse at the next pole again. And
the phase may change too (i.e. vertical to horizontal to vertical
again). Without good equipment like a yagi, you probably won't notice a
phase difference as long as you hold the rcvr at the same angle all the
time.
Once you've found good clean areas, start listening at higher
and higher freqs like 30-150 MHz (again AM mode, not FM) and do the same
thing in the noisy areas. You shouldn't have to go as far away to find
quiet low noise areas this time.
This is important: The higher in frequency you tune to listen
to the noise, the closer you have be to the source to hear it. Keep
this in mind as you tune and wander around.
Without a VHF yagi and VHF AM rcvr, it will be very time
consuming and perhaps impossible to narrow it down to the single noisy
pole. I recommend getting this equipment to conduct your search ASAP.
You don't want to tell the power company it's that pole over there and
then be wrong. They might not come back to correct the right pole when
you finally do find it. And be cautious about multiple noisy poles
where only one of them is causing your noise.
Sorry about the length of the message. Good luck finding your
noise, and I wish you even more luck in dealing with the power company
getting it resolved in this era of utility deregulation.
73,
de ed -K0iL
-.-. --.- -.-. --.- -.. . -.- ----- .. .-.. .-.-. -.-
Ed Edwards Communications Engineer
Omaha Public Power District 2-Way & Paging Systems
--... ...-- . ... --. .-.. - --- ..- --- -- ...-.- . .
Still not Deregulated in the only state with NO private utilities!
Nebraska!
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