Nothing at all above 24Mhz? And nothing at all below 7 Mhz?
Or is that just the range of your antenna system?
You said two noises; have you heard one without the other? Or always
together?
What time at night does it go away? 10 or 11pm? After midnite?
It sounds like it might be some sort of device (Part 15?) in someone's
home in the neighborhood. Particularly due to the times involved; it
sounds like it's associated with a human's activity schedule versus
non-human events like the weather. It doesn't sound like it would be
powerline noise, although if it is conducted from some distance away,
you might get that freq range due to some weird resonance effect. It
does follow electrical system loading somewhat (although it should peak
in the morning and then again after work--not at noon).
Since you have noted the direction it's coming from, get a map and plot
a line in that direction. Then go mobile targeting streets along that
bearing. Once it gets stronger, find the freq it peaks at, then go
higher to see if the freq range has changed. If so, go to the highest
freq at which you can still copy it. Then keep following the bearing
and tuning higher until you're into the VHF high-band (2-meter or
higher). Then go portable with an VHF AM-mode radio like an Air-band
radio.
If the freq range stays the same, then it's probably a specific device
in a home. Tune to the edge of the freq range where it's weaker and
continuing to hunt will help you close in on its location hopefully.
Good luck!
73, de ed -K0iL
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Scott Ginsburg
Sent: Monday, June 14, 2004 8:50 PM
To: rfi@contesting.com
Subject: [RFI] need ideas on hunting down QRN-like noise source
I'm currently plagued with two sources of HF RFI, and for the
moment am concentrating on locating one of them. Any help
I can get from the RFI sleuths on the list would be greatly
appreciated!
The noise in question showed up about a month ago, and appears
as a combination of white noise and random, rapid static crashes.
The static crashes, or bursts, sound a lot like heavy QRN.
It is typically the loudest on 14 MHz, and can be heard from 7-24 MHz
when it's at its worst, with peaks on 14 MHz of 10 over S9. I hear no
buzzing when listening on AM. My noise blanker has no effect.
Its presence can't be correlated with weather. I hear it on both wet
and dry days, wind or no wind.
It seems to peak from a certain direction when I listen on my HF log
periodic. I've driven the neighborhood streets (up to 2 mi away) with my
706 and hamstick in the car and can hear what I think is the noise in
certain locations, but never loud enough to be a "smoking gun". I
verified it's not coming from my house, by killing power and listening
in the driveway on my 706 to the noise.
Early morning is typically very quiet. At 6:30 AM local time I usually
hear only silence, or a few weak bursts of noise which sound like the
problem. It typically peaks by noon. I almost always hear it in the
evening and at night.
Any hints anyone might have as to what a possible source might be or
the best way to continue trying to track this down would be
appreciated.
73,
Scott, K1OA
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