[RFI] Am I hosed? RFI problems

[Paul Christensen]

Kelly,

You'll need to start documenting the interference.  To the best of your 
ability and time, keep a log of the times the interference starts and 
stops -- even if its days in between.  As has been suggested here on 
numerous occasions, first ensure that the interference is not coming from 
your own property.  That involves turning off all panel breakers and 
disconnecting battery-backed systems (e.g., security alarms).

It's unreasonable for the neighbors to be turning on/off power without 
evidence.  You need to secure some minimal evidence before making contact 
with them.  If you don't, you're only a boy crying "wolf!" at best.  At 
worst, you've just become the new neighborhood crackpot.

The mind begins to conjure all kinds of things when the interference is 
really bad.  "I need to move," "questionable renters," and "super powerful 
computers" mean nothing when you really need to flesh-out the root cause of 
interference.

Today, we're confronted with more sources of interference than ever before. 
But fortunately we have some tools that were not available until recently. 
It may take you some time, but if you want to get really proficient at noise 
source detection, you're going to have to become knowledgeable with noise 
patterns and select the right equipment for detection.

Before contacting neighbors, utility company or the FCC, you really need to 
have your facts straight.  Simply turning your beam in the direction of the 
perceived noise source isn't nearly enough.  You've got to localize it 
through triangulation.

I have two systems here:

(1) The first is a hand-held 3-element 2m Yagi and a 2m HT capable of AM 
mode.  This system is primarily used for broadbanded power line noise;

(2) The second system has been seeing much more use here in the past year, 
primarily due to the increased proliferation of switch-mode appliances.  It 
consists of an Elecraft K3, SDR-IQ with SpectraPlus software, netbook PC, 
Palstar active rotatable loop antenna, and a small 12V gel-cell battery.  I 
purchased a mid-size Pelican case to allow me to quickly set-up and break 
down the equipment as I roam the neighborhood.  I generally do not need to 
access the neighbor's property.  Most of my measurements are taken at the 
street or from within my property.

After some time spent with switch-mode noise sources, I can now localize a 
noise source in about 30 minutes to nearly pin-point accuracy.  However, 
some noise begins in a room of the home, and the home wiring propagates the 
noise to make it appear as if its coming from a different part of the house. 
That's one reason why it's so important to move around and take quality 
measurements.  My system is self-documenting.  I take PC screen captures of 
SpectraPlus showing noise levels all pointing to a single location.  That 
becomes my evidence for presentation to a neighbor, or if necessary to the 
FCC.  When you've got that kind of powerful data, the FCC is really on your 
side.  But you cannot go to the FCC and talk in terms of "questionable 
neighbors," and "super powerful computers."

It may seem like this is all going over-the-top in equipment and procedure, 
but if we want to enjoy the hobby without running a noise blanker all the 
time, we all need to become proficient in recognizing noise source patterns 
and know how and what type of equipment is needed to detect the problem with 
a high degree of accuracy.

Paul, W9AC

---- Original Message ----- 
From: "Kelly Johnson" <n6kj.kelly at gmail.com>
To: "RFI List" <rfi at contesting.com>; <mike at rfiservices.com>
Sent: Sunday, August 15, 2010 10:19 PM
Subject: [RFI] Am I hosed? RFI problems


> It took me two weeks, but I'm now about 99% certain that I found the
> source of my horrible RFI problem.  It's a house about 100 yards from
> me.  A group of questionable renters just moved into that house a few
> weeks ago.  The noise is worse than anything I have ever heard.  It's
> S9/S9+ on 40m through 10m; dropping down to S7 or so on 6m (all while
> I beam that direction, which is unfortunately the direction I must
> beam for the East Coast from here in CA).  I can null it out if I beam
> perpendicular to that direction, but unfortunately, there aren't that
> many stations of interest directly north or south of me :-(
>
> When I told the renter today that I have heard the noise start at 8am
> the last 2 days, his first response was: "there's a guy here that has
> a very, powerful computer that he turns on at 8am".  He asked the guy
> to turn it off to see if it was the source and the guy clamed to have
> done it, but I don't believe he did.  I think he was just trying to
> get rid of me.  The noise was still there.  When I asked the guy if he
> would be willing to shut everything off to see if it went away he said
> no.  I don't know what to do now.  My HF station is nearly worthless
> at this point with S9+ noise.  I can't hear much of anything above the
> hash.  My S meter read S0 last night at 10:30pm and still S0 this
> morning from 6am until 8am.  I was sitting in front of the radio at
> 8am when the noise came on.  The S meter instantly jumped from S0 to
> about S7.  It slowly got worse until it peaked at S8 on CW in a CW
> 250HZ bandwidth and S9+ in a 2KHz bandwidth on SSB.
>
> Any advice (other than move, wait for these guys to move, or something 
> illegal)?
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>