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Author Topic: 40M CW Interference  (Read 1065 times)
W9AC
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Posts: 53




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« on: June 05, 2009, 06:29:00 PM »

For the past week, the low-end of 40M has been inundated with a broad "chirp like" digital interference, concentrated between 7.015 MHz and 7.040 MHz.

Signal strength is much reduced during daylight hours, but still noticeable. Anyone know what this is?

Paul, W9AC
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W4YA
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Posts: 317




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« Reply #1 on: June 05, 2009, 06:49:16 PM »

Sounds like bongo drums.
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W5HTW
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« Reply #2 on: June 06, 2009, 05:13:37 PM »

I hear it quite well down to 7002 khz.  And at much lower signal strengths a bit higher in the band.  No real idea what it is, but not amateur.  May be some sort or ranging signal.  

Ed
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K0OD
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Posts: 2521




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« Reply #3 on: June 06, 2009, 05:44:08 PM »

I heard it yesterday loud in Missouri.
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W5UXH
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Posts: 20




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« Reply #4 on: June 06, 2009, 05:52:53 PM »

It was also active last December I think, but seems much worse when active these days.  The question was recently asked on another group and W4BQF commented as follows:

"That is just some digital junk coming from over in eastern Europe. It is not PSK or any of the standard digital modes. Not too much we can do about it except QSY! It is a PITA!!"

I don't know what it is myself, but it gets pretty bad in New Mexico at times.  Last night it was really bad, tonight I do not yet hear it.

Chuck, W5UXH
Las Cruces, NM
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M0RGJ
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Posts: 3




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« Reply #5 on: June 07, 2009, 07:29:29 AM »

This was part of thr rsgb news,hope it explains !

Radio Ethiopia causes interference on new 7MHz segment

If you regularly listen into the new 7100 - 7200kHz range in the evening hours, then you may have noticed some interference. Starting 1630UTC and lasting about one hour, you will find on 7165kHz, or sometimes on 7175kHz, a powerful wideband rushing noise, which is some 15kHz wide. Also very faintly you can hear the carrier of a program below the jammer. The culprit is Radio Ethiopia. It is jamming Voice of the Broad Masses from Eritrea on 7165kHz. Ethiopia also regularly jams other transmissions in Amharic, for example Deutsche Welle, on 15 and 11MHz. The jamming uses a rectangular white noise signal that is some 10 to 16kHz wide. In 2008 Ethiopia commissioned 3 or 4 new transmitters, some of which are regularly used for jamming unwanted programmes. To see a screen shot of the jamming signal, check out the IRY Region 1 website.
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W5UXH
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Posts: 20




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« Reply #6 on: June 07, 2009, 08:11:20 AM »

M0RGJ commented:
"This was part of the rsgb news,hope it explains !

Radio Ethiopia causes interference on new 7MHz segment "

I doubt that his is what some of us have been hearing.  Some descriptions call it "bubbling water" or "gurgling" or "dripping".  On the low end, each segment of qrm is roughly 4 to 5 KHz wide, with perhaps another 5 KHz or so gaps where you do not hear it.  I think it usually has these short segments spread between around 7015 and 7040 or 7050.  It definitely is not white noise.  Very unusual warbling tones.

Chuck, W5UXH
Las Cruces, NM
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W5UXH
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Posts: 20




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« Reply #7 on: June 07, 2009, 08:20:50 AM »

Here is a link to two recordings (MP3 files), one from Dec 2008 and one from this past week in June 2009:

http://sites.google.com/site/w5uxhcw1/40m-gurgling-qrm

I have been assuming that the other comments I have read about strange QRM are from folks hearing the same sort of junk, because some of the descriptions are so similar, referring to dripping, bubbling, gurgling etc.

Chuck, W5UXH
Las Cruces, NM
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K5END
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Posts: 1309




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« Reply #8 on: June 08, 2009, 08:25:52 AM »

I used to hear this a lot on 17 meters...somewhere here on eham is a post and thread less than a year old, discussing it showing up on 17 m.

Right now it's loud in Houston on 40 m.

Some say it's like the Maxwell House coffee commercial jingle...remember that one with the coffee pot and the little glass bulb?

Of course NOW we have to settle the dispute of whether it was Folger's or Maxwell House.

It reminds me of the 1970 Moog single, "Popcorn."

Personally though, I like to think of it as the air bubbles that result from holding the heads of SSB Lids & jammers under water...especially the guys who tune or whatever they are doing right on top of a QSO. This weekend was especially bad on 20 meters SSB.

Each time I try SSB I find that I like CW all the more.
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K5END
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Posts: 1309




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« Reply #9 on: June 08, 2009, 08:29:57 AM »

Funny that this latest percolating interference/QRM doesn't show up in the Elmers or RFI forums.

I guess that might mean the keyboard/forum/SSB hams don't really get on the air very much.
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W9AC
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Posts: 53




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« Reply #10 on: June 08, 2009, 08:57:57 AM »

Here in the southeast U.S., the signal strength of the chirp-like percolating on 40m CW is pretty intense.  I'll forward this to the ARRL and FCC for comment.  Hopefully, the FCC can localize the source.

Paul, W9AC
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W9OY
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« Reply #11 on: June 08, 2009, 09:41:13 AM »

On my pandadapter in the Flex radio it is actually in "bands" of noise with several khz of no noise in between the bands of noise, enough for a dozen cw qso in the quiet part

Probably another OTH radar  quite annoying

73  W9OY
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K5END
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Posts: 1309




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« Reply #12 on: June 08, 2009, 10:28:44 AM »

.
I asked a retired USAF/FAA career radar expert I know and he doesn't think it's radar--but wouldn't rule it out either.

Would be very interesting to know what this is, as I have heard it many times in the past on 17 m; as I recall it was around 18.078-18088, give or take.  

Maybe Olivia had a daughter?
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K0OD
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Posts: 2521




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« Reply #13 on: June 08, 2009, 10:40:04 AM »

Several hams from around the world using 40 meter directional antennas could DF this very accurately given some time. 4-square arrays, which have instant rotation, work well for that purpose. Remember the whole path is likely to be in darkness or twilight. Check long and short paths and keep records.

I wonder whether the League contacts other national ham organizations or the FCC about these intruders. Unless this is coming from North Korea, surely some ham somewhere is just "down the road" from the source.

---
OTOH, years ago I called the ARRL about a very well known beacon intruder and I was shocked to be told they weren't even aware of it!
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K5END
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Posts: 1309




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« Reply #14 on: June 08, 2009, 12:11:13 PM »

I sent an email to ARRL about this and had an email reply from real people in less than 5 minutes.

The ARRL has already contacted the FCC and opened a case for this.
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