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Author Topic: Radar interference?? Anyone have an idea.  (Read 2862 times)
AJ4RW
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Posts: 568




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« on: November 29, 2012, 06:05:56 AM »

I've heard this numerous times on the amateur bands, some type of enormous noise interference.  This morning I was on 17 meters listening to 7P8D using RTTY while I cooking breakfast in the other room waiting for their signal to improve.  When all of a sudden I heard this fast palsating noise about 10 over S9.  I started scanning the band to see how wide and found it to be 24 kcs wide, wow.  I brought up the cluster and saw where someone had posted that it was "radar".  My question is:
1. Is it radar?
2. Where is it coming from?
3. If it is radar, then why does it need to occur on the amateur bands?
4. Is it malicious or just normal operating procedure?
This is a curiosity question.
Randy
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W6GX
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Posts: 3007




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« Reply #1 on: November 29, 2012, 06:20:39 AM »

I hear it too all the time.  It comes on and then stops.  I don't understand the intermittent nature of the QRM.  I'm interested in hearing the answers to Randy's questions.

I hope it's not another Russian Woodpecker.

73,
Jonathan
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KY6R
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Posts: 3277


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« Reply #2 on: November 29, 2012, 08:13:17 AM »

We hear it on the West Coast all of the time. Sometimes on 80M, sometimes on 40M. It has been spotted in every case as Chinese Radar in the Pacific. It is almost always in the morning.
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W6GX
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« Reply #3 on: November 29, 2012, 08:22:07 AM »

Now we could call it the 'Chinese Woodpecker'  Cheesy

Does the FCC ever investigate this type of interference?

73,
Jonathan W6GX
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KY6R
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« Reply #4 on: November 29, 2012, 08:57:29 AM »

Now we could call it the 'Chinese Woodpecker'  Cheesy

Does the FCC ever investigate this type of interference?

73,
Jonathan W6GX

I doubt the FCC can do much of anything about it.
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N3QE
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Posts: 2364




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« Reply #5 on: November 29, 2012, 09:08:51 AM »

I hear it too all the time.  It comes on and then stops.  I don't understand the intermittent nature of the QRM.  I'm interested in hearing the answers to Randy's questions.

I don't have "the answers" but if it's anything like the woodpecker then they are doing some kind of frequency hopping. May be in ham RTTY band for minutes but then later it's somewhere else probably clear of any ham band.

The woodpecker was clearly operating in pulse mode (and I know big tubes can have pulse ratings) but I wonder if this new wideband-continuous mode is thermally limited at the source.

Just think if we had a QRO amp with this kind of rating :-)

More often than this noise, I am bothered by some sort of ALE noise in the RTTY bands. I don't think that's radar, I think that's other hams, probably using some form of unattended equipment. The ALE can be semi wideband (kHz) but not tens of kHz.

In the CQ WW CW contest, some really irritating and strong digital mode came up unattended while I was trying to run on 15M. It sounded just a little broader than a pure carrier, not the tens of kHz nor even the width I associate with ALE.

Tim.
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NU1O
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Posts: 2749




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« Reply #6 on: November 29, 2012, 09:48:16 AM »

I've received it several times and it was as wide as Randy states. When I've seen it spotted it has normally been called "Russian Radar".  The guys in Europe are typically the guys who label it as Russian so I would think they can distinguish Russian radar from Chinese radar from their beam headings when the signal is emanating from European Russia.  It's probably more difficult to determine the source as Chinese or Russian when the signal is emanating from either Asiatic Russia or Northern China.  A guy like Klingenfus has digital recordings of thousands of signals. He could probably discern different types from their spectrum signatures and he may actually be able to pinpoint the location as he has monitors all over the globe. 

Good luck in getting Russia or China to stop using it. If they didn't think they needed it for national defense they wouldn't be bothering with it in the first place since it must be very expensive to build and operate.

I would not waste my time complaining to the FCC over a foreign radar signal.  Fortunately, on the occasions I have heard the radar it didn't stay on the same frequency for a very long time.

73,

Chris/NU1O
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K4JK
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Posts: 320




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« Reply #7 on: November 29, 2012, 11:47:43 AM »

I've heard that on 17m too, I think. Sounds like a Chinook taking off about 200 yards away. I've heard it described as Chinese OTH radar too.
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ex W4HFK
N2NL
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Posts: 364




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« Reply #8 on: November 29, 2012, 02:21:27 PM »

There are a number of different OTH radars on the bands.  The big one is the Chinese "Dragon" which is often on 40m but seems to be permanently located on 60m now.  I've heard it on other bands as well.  I think it follows propagation.  There are other radars that show up briefly on other bands then disappear - whether they are Chinese or not I do not know.

From Guam the Chinese radars are very loud - many dB over s9.  They are probably directed at Guam where there is a large Air Force presence including forward deployed strategic bombers (this is common knowledge and not a violation of OPSEC).

Nothing we or the FCC can do about it.  Even worse is the Chinese QRM on 10m caused by two-way commercial FM and AM radio traffic.  It has destroyed 10m any time the band is open to China (which means EU also).  Here is a MP3 of what it sounds like here.  Nothing you can do about it - otherwise 559 signals are completely obliterated by it. 

http://www.n2nl.net/wordpress/wp-content/uploads/2011/05/10mnoise.mp3

73, Dave
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AF3Y
Member

Posts: 3851




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« Reply #9 on: November 29, 2012, 02:38:54 PM »

Hey........ Just give the guys up at Fort Meade a buzz and ask who it is and what it is. They could
tell you, but I dont think they will. Radar emissions are a big deal. (At least they USED to be Grin)

73, Gene AF3Y
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