Hi, Dennis,
That sure sounds like electrical noise.
Under Part 15 of the FCC's rules, power lines are "incidental emitters."
Incidental emitters are devices that don't deliberately generate RF energy, but
happen to do so as an incidental part of their operation. Other examples are
electric motors, fluourescent lights and arc welders.
Under the rules, incidental emitters do not have a specific limit for either
conducted or radiated emissions. They are required only to meet two criteria.
The manufacturer of an incidental emitter is required to use "good engineering
practice." In most cases, the utility company has constructed the power plant,
so they can be loosely construed as the manufacturer. The rules then stipulate
that the operator of an any unlicensed emitter of RF energy must operate it in
a way that does not cause harmful interference.
Fortunately for utility companies, these requirements do not require that every
single potential noise source be found and eliminated. Only those that cause
harmful interference to radio services, such as the Amateur Radio Service, must
be corrected to the point where they no longer cause harmful interference. In
this case, if the tree falls in the forest and there is no one there to hear
it, it does not make a sound and no action is required.
There may, however, be some pretty powerful reasons to try to correct *serious*
radio noise, even if it is not causing actual interference. In some admittedly
rare cases, strong radio noise can indicate a strong arc that could burn
through the conductor, dropping the line to the ground. Although not every
noise indicates that severe of a problem, every single line that does arc open
and drop would have had strong radio noise as a precursor to the problem. And
of course everyone in the utility industry would agree that if such a serious
event were prevented only every few years, the relatively small amount a
utility company spends on interference prevention during that time was well
justified.
Not all radio noise is the responsibility of the utility company, however.
Electric utilities are responsible only for harmful interference caused by
their equipment. Most cases of electrical noise reported to the utility
companies by customers actually turn out to be caused by non-utility equipment.
Things like fluourescent lights, some computers, thermostats, oil burners and
a host of other equipment can and does cause electrical noise. The source may
well be in the complainant's own home. Naturally, you have no control over
what equipment can be connected inside your customers' homes and businesses,
nor do the rules make you responsible for this non-utility equipment.
By the time a case gets to the ARRL for resolution under our cooperative
agreement with the FCC, we have worked closely with the involved amateur
operator. We have first determined that the complaint does indeed sound like
power line noise and that it is strong enough that it is clearly causing
harmful interference. In this case, the level is very strong at the amateur
station. Amateur operators also have passed an FCC technical examination and
between the involved ham and ARRL's staff, we have eliminated the amateur's own
home as a probable source and have usually been able to determine that the
problem is apparently coming from the utility equipment and not a neighboring
home or business.
Tracking down these noises can be a challenge and in some few cases, what has
appeared to be a utility problem has proven to be something else, but a
good-faith effort has been made by all to really believe that the utility
company is involved and that the noise levels truly are harmful interference as
described in the rules. Naturally, if any investigation by the utility company
does demonstrate that the source is not the utility company equipment, ARRL
will work with the amateur to help explain that the company is off the hook and
that the matter needs to be taken up with the actual source.
After the intial stage of working directly with the amateur, ARRL then
encourages the amateur to try to resolve the problem directly with his or her
utility company. In many cases, finding and fixing such problems is routine,
with many companies having trained staff to sniff out these problems. If more
training is needed, a company called RFI Services offers utility companies
classroom training in the types of equipment and skills needed to track down
the problems. See http://www.rfiservices.info/. Thier client list, available
on their web page, includes some major utility companies.
If the local approach doesn't work, ARRL then contacts the utility company CEO,
under our agreements with the FCC. That often serves to get things moving in
the right direction. In some cases, we have had to ask the FCC to send a
similar letter. Both letters are really asking for only a few basic steps:
communicate with the complainant (and the FCC, if the FCC letter was received)
and identify and correct any noise sources from utility equipment that are
causing harmful interference.
This process has been worked out by the FCC and ARRL through years of trial and
error. It is intended to try to facilitate local solutions to local problems.
The letters are intentionally advisory because this gives the involved parties
more flexibility to work things out in a reasonable time frame. Amateurs
benefit because such advisory communications are usually faster and more
effective than formal investigation by FCC field agents. Utilities benefit
because this keeps the investigation and solutions under their direct control.
In my opinion, this is better than any solution imposed from the outside, where
the FCC could be asked to draw lines in the sand about interference levels,
possibly requiring amateurs to accept more interference than they would like or
requiring utility companies to take steps system wide to demonstrate that their
system does not pose a significant interfernece potential over a wide area.
There is rarely any benefit to literally making a federal case out of what can
be resolved as a local, customer-service issue.
The major impedements I have seen to utilities successfully resolving the cases
are communications problems and training. If you think of the logistics to
getting this unusual complaint through the customer-service agents to the
people utimately responsible, you are just touching the problem. Some of these
cases can be complex and I have seen the overworked RFI troubleshooters, who
almost always have "real" jobs in the utility, try to track down S6 noise
(which could be coming from a mile or so away) with a handheld RF sniffer in
the ham's backyard.
In other cases, there are multiple noise sources and the problem isn't really
corrected until they are all located. In many cases, not every noise source
that is found close to an amateur can be heard at the amateur station! The
'real' source might be a half mile away for moderate noise, but in between are
a number of sources that are strong very close to the source but that do not
propagate down the line to cause problems. Under the rules, those noise sources
don't have to be found or fixed. The RFI Services workshop shows how to obtain
a noise signature at the amateur station, then compare that to the noises heard
on the lines. If the signatures match, it is very likely that the actual noise
has been found.
In many cases, utilities have spent a lot of money fixing the wrong noise.
Naturally, the utility company sees that from the perspective of the resources
that have been spent. In the minds of the utility management, each repair was a
"fix," and they want to know how much more they have to fix to satisfy this
customer. In the amateur's mind, they didn't fix anything at all, becauase the
noise is still there. Add to this what I call the BUL syndrome (Big Ugly
Lineman). The troubleshooter may correctly identify a cracked insulator as an
RF source, but when the BUL climbs the pole, he sees the cracked insulator, but
says that he has seen them work that way for years, so nothing needs to be
replaced. Okay, that is a bit of an exaggeration, but we have reports of field
crews not doing as thorough a rebuild of a pole as the troubleshooter has
envisions. In most cases, the troubleshooting and repair crews do not contact
the amateur to verify the fix, so in their view, the problem has been taken
care of and they are on to the next crisis.
Naturally, all the utility management folks are asking why this problem is
costing so much money. In many cases, the proper equipment and training could
have shaved a lot of the costs down to something a bit more manageable.
ARRL stands ready to help in any interference problems involving amateur radio.
ARRL's info on electrical interference is found at:
http://www.arrl.org/tis/info/rfi-elec.html
73,
Ed Hare, W1RFI
ARRL Lab
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Internet: w1rfi@arrl.org
Web: http://www.arrl.org/tis
ARRL is the National Association for Amateur Radio. It is supported by
membership dues, individual contributions and the sale of publications and
advertising. For more information about ARRL, go to
http://www.arrl.org/news/features/inside-your-league.html. For more information
about membership, go to http://www.arrl.org/join.html. Your contribution can
also help support ARRL's ongoing efforts to protect Amateur spectrum. Go to
https://www.arrl.org/forms/development/donations/basic/ to learn more about the
ways you can support the ARRL programs and activities of most importance to
you. You can help ARRL protect Amateur Radio for you and future generations to
enjoy.
> -----Original Message-----
> From: dennis peterson [mailto:k0ckdennis@machlink.com]
> Sent: Monday, January 13, 2003 12:28 PM
> To: rfi
> Subject: [RFI] s7-s9 noise
>
>
> I run s7-s9 noise 24 hours a day on my Kenwood TS-870 transceiver.
>
> I have noticed that there are no ground rods grounding the
> D-Mark box for cable tv and telephone or internet services.
> Instead, they ran a #8 wire or maybe 10 wire 35 feet on top
> of the ground over to the power pedestal and wrapped it
> around a screw on the top back side of the pedestal.
>
> To me this doesn't seem appropriate or correct. Could I be
> picking up noise thropugh the 35 foot wire on the ground
> which may be actng as an antenna and comming into the home?>
>
> Also, this is an older home with the older type wiring and it
> does not have or include the three wire system ONLY two-wire.
> I notice this predominantly on 160 meters.............
>
> Any help and or suggestions greatly appreciated. Sorry for
> the bandwidth on this, but I've had this problem now for
> sometime and I'm new to this reflector so please excuse the
> ignorance at this time.
>
>
> 73S
>
> Dennis----------K0CKD
>
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