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Author Topic: 40 meter jamming (?) heard at 10 P.M. PST 9/23/09  (Read 1756 times)
AL7GS
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Posts: 3




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« on: September 24, 2009, 11:08:15 AM »

Last evening I turned on my Argo V and was surprised to
hear what was reminiscent of a "woodpecker-like" s-7 to s-9 signal that seemed to peak at about 7.050 and was at least 100 kilohertz wide...anyone else hear this?
Anyone have a clue as to its origin? There was some qsb on this thing. Hope this isn't local and that it goes away!
Appreciate your comments!
73, Howard
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WB5JEO
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Posts: 805




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« Reply #1 on: September 24, 2009, 01:46:04 PM »

If it's what's been commonly heard for a long time, it's generally presumed to be OTH radar, possibly China, but there are other suspects. Much faster and more motor-like, rather than the pecker's tapping.

Check about halfway down in the Radar section:
http://www.iarums-r1.org/iarums/sound/main.html
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KG4DGF
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Posts: 50




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« Reply #2 on: October 01, 2009, 01:08:56 PM »

Speaking of 40, did anyone catch the jammin tunes on 7.110FM last night?
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CA2VMP
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Posts: 9




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« Reply #3 on: December 14, 2009, 08:13:52 AM »

i hear it all day long over the 40 meter band , normally sweeps from 6780 to 8400 Khz , and the signal is about 100 to 200 Khz wide  S9+10 here in Chile South America .i ve ever heard it on portions On the CB band .
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EI5CD
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« Reply #4 on: February 10, 2010, 03:45:55 AM »

re 40m jamming I would like to know if this is a slow pulse type, as I have been hearing a 5 pulse per second signal across 7 and 8 MHz for a long time,relatively low level but enough to disturb weak signals. Not a harsh pulse like old 'Woodpecker' but more like chuff-chuff-chuff (helicopter blade). Also heard around 12 to 14MHz and from 19MHz up to beyond 25MHz at times, interfering with 21MHz. Also has a variation, about 6dB across 40kHz, ie max at 8000kHz,min at 8020kHz,max at 8040khZ etc. To hear it you need to have low background QRN, no CFLs,switch mode PSUs,plasma TV or other noisey electronics.My be from S E Asia, not a RADAR, very unusual transmission.
Des WALSH EI5CD  e-mail des.walsh@iaa.ie
Feb 10 2010
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WB5JEO
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« Reply #5 on: February 10, 2010, 11:43:00 AM »

There's quite a variety of HF RADAR being used in oceanography, mostly mapping wave height and direction. As I understand it, the whole HF spectrum is used, because different wave heights effectively reflect different frequencies. Doppler shift detects wave direction. (Usually requiring two transmitter sites.) Pulse rate can be all the way down to 2 per second or very much faster. And surface wave HF surveillance RADARS can run pulse rates of 4 to 50 Hz. (The USSR's "woodpecker" was sky wave.)
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K4KYV
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« Reply #6 on: March 30, 2010, 11:37:50 PM »

The signal on 7110 is Radio Ethiopia.  They transmit from 0300Z until 2100Z.  At least they stay within that wasteland between 7100 and 7125, where US phone stations are not allowed by FCC rules but very CW/data stations are ever heard operating.

More troublesome is the Voice of the Broad Masses of Eritrea.  They fire up at 0400Z on 7175, and at that same time, another Ethiopian or Eritrean broadcaster starts up on 7165.  Almost immediately, white noise jamming starts up on top of the station on 7175, so they QSY to 7165, zero beat with the other BC station.  The white noise then follows them to 65. There may be two broadcasters on the same frequency with the white noise jamming on top of them.  Sometimes they play this cat and mouse game all evening, until fade-out sometime after 0600Z.  This can be very disruptive all the way from 7155 to 7185. A few times I have heard a white noise jammer on both frequencies simultaneously.  When that happens, much of the supposedly broadcast-free spectrum between 7125 and 7200 becomes useless.

This noise is jamming.  It is not DRM or digital SSTV as many believe.

If they would only QSY all this garbage to 7100-7125, at least they wouldn't bother anyone much, at least in N. America.  After a full year, it is obvious they don't plan to abide by the new allocations and vacate 7100-7200.

Don k4kyv
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