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Author Topic: Mystery signal question  (Read 65499 times)

Offline Token

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Re: Mystery signal question
« Reply #60 on: November 14, 2016, 0156 UTC »
How about radar astronomy, an active radio-astronomical technique of observing nearby objects in the solar system (asteroids, comets, etc.)? There are microwaves are mostly radiated, but Arecibo Observatory in Puerto Rico, for example, has also one 6 MW radar transmitter system for 8 MHz band, so SW is also being used for this purpose? Could China or Japan, for example, have the similar systems operating on SW? Are short wave frequencies being used on Goldstone Solar System Radar too?

I think the Aricebo HF transmitter is 0.6 MW, not 6 MW.  Regardless, no these are not radio astronomy.  They are almost certainly noise from some production technique, RF welding, etc.

And no, Goldstone does not do HF.

T!
T!
Mojave Desert, California USA

Offline ulx2

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Re: Mystery signal question
« Reply #61 on: November 14, 2016, 2138 UTC »
I think the Aricebo HF transmitter is 0.6 MW, not 6 MW

6 MW is EIRP, I guess.

Quote
They are almost certainly noise from some production technique, RF welding, etc.

The HF generators of such industrial plants must have frequency inside specially allocated ISM bands which are mostly the same in various countries: 6765 - 6795 kHz, 13553 - 13567 kHz and 26957 - 27283 kHz for SW. And even taking into account the fact of presence of non-standardized plants of such kind or some spurious emissions, the most activity of the "sweepers" must be observed on these ISM bands. However, it is not obviously on the posted screenshots: they are active on 24 and 28 MHz instead.
« Last Edit: November 14, 2016, 2233 UTC by ulx2 »
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Offline Token

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Re: Mystery signal question
« Reply #62 on: November 15, 2016, 1339 UTC »
I think the Aricebo HF transmitter is 0.6 MW, not 6 MW

6 MW is EIRP, I guess.


The Aricebo ERP is 220 MW at 8175 kHz and just under 100 MW at 5200 kHz.

Quote
They are almost certainly noise from some production technique, RF welding, etc.

The HF generators of such industrial plants must have frequency inside specially allocated ISM bands which are mostly the same in various countries: 6765 - 6795 kHz, 13553 - 13567 kHz and 26957 - 27283 kHz for SW. And even taking into account the fact of presence of non-standardized plants of such kind or some spurious emissions, the most activity of the "sweepers" must be observed on these ISM bands. However, it is not obviously on the posted screenshots: they are active on 24 and 28 MHz instead.

Yes, and those facts are why I did not say these signals ARE from things like RF welding, and rather said "almost certainly".

However, I have seen visually identical signals from a plastic welder, and it was slightly outside the ISM bands (in that case 25 - 26 MHZ).

Combine that with the fact I see the majority of these signals (outside the ISM bands) when propagation is in from Asia, and China is well known for ignoring the rules and doing their own thing, and I think the majority of these that I see are quite possibly, almost certainly (but not quite certain) are some similar industrial technique.

Of course, that is why this is still a mystery.  A list of possible sources has been ruled out, the most probable source should not be happening on these frequencies, and at this point we are still guessing.

With the signals I was looking at locally there was a definite reduction in number visible on any given Sunday.  I plotted this over a period of 6 weeks and every Sunday the number was less than one tenth of what was seen on Saturday and Monday.  This is a strong indicator, in my opinion, that these signals are man made.

The waveforms are unstable and varied, especially in phase.  And there are seemingly many different sources up at any time (based on propagation and antenna bearings).  These would argue, to me, against things like research facilities, which should be few in number and probably using more traditional or predictable waveforms.  Also, research tends not to avoid one specific day of the week, you generally do research when you can get the time on the facility or when the conditions are right for your tests.

Just my opinion of course.

T!
T!
Mojave Desert, California USA

Offline ka1iic

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The 'curly' signal... picture no audio
« Reply #63 on: February 11, 2017, 1659 UTC »
Don't know what this is but I have seen it a few times but this is the best pic of it so far...

I call it the curly signal  or hook signal... tell me what everyone else is calling it please so we will all be on the same page...  perhaps :-)

vgw
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Offline Token

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Re: Mystery signal question
« Reply #64 on: February 11, 2017, 2301 UTC »
Vince, I moved your post to this thread, since it is the same kind of signal discussed here.

Almost certainly some kind of industrial process, I have seen identical signals in the 25-26 MHz that I could trace directly to an RF plastic welding machine.

The problem is as stated a couple posts above, those machines are supposed to fall in a few narrow freq ranges, and these signals are seen across far wider freq ranges.  I suspect they are from non-compliant devices, or possibly DX from nations with looser requirements.

T!
T!
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Offline ka1iic

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Re: Mystery signal question
« Reply #65 on: February 12, 2017, 1424 UTC »
Thanks Token.  No problem with the move OM, I knew it was miss placed but I'm playing with this SDR and loving it so, if you might, take that as an excuse :-)

The welding thingie makes total sense when I consider the types of businesses within walking distance of my apartment.  With 2 large auto sales and service outfits and one aircraft equipment outfit and others I haven't seem as of yet.  I gave up on the S&D ideas a year or two ago, now I plan 'workarounds'.

I'll have a few strange ones to post tho.  The sweeper (sounds like a vfo) isn't just one sweep but it appears to be two at the same time.  Hmmm.  And of course OTHR... tons of them and some of then aren't playing by the rules... ;-)

later Sir!
vw
73 Vince
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Troy, Ohio. 20m Vertical & low long wire E/W, Yaesu FT-187ND, SDRplay 2, Ratt Shack 2 meter rig, and other little bits of electronics I'm not talking about, homebrewed and otherwise... so there bleech!

Offline Cornel

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Re: Mystery signal question
« Reply #66 on: July 20, 2017, 2227 UTC »
No sliders nowhere hr. Nil.
http://www.rfsafetysolutions.com/Workplace%20Safety%20Pages/RF_Heat_Sealers.html

"1.5-60kW and more output power...For years, many RF heat sealers were not well designed in terms of RF safety."
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Offline ChrisSmolinski

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Re: Mystery signal question
« Reply #67 on: November 27, 2018, 1340 UTC »
I'm recording the 73m band for pirates now, and last night noticed some of our sliders around 0700 UTC:

Chris Smolinski
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