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Author Topic: Mystery signal question  (Read 66568 times)

Offline Cornel

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Re: Mystery signal question
« Reply #45 on: October 08, 2015, 1959 UTC »
Today ~18:00z 24000-25000, RTL SDR F0013. They live!

Cordoba, Argentina.
JRC NRD-545, JRC NRD-525, FRT-7700, RTLSDR F0013, 40m of wire @ 8m, vertical whip on @ 7m

Offline Cornel

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Re: Mystery signal question
« Reply #46 on: October 11, 2015, 1827 UTC »
...and sunday 11.10.2015 the same range 24000-25000kHz, ~18:00z
Cordoba, Argentina.
JRC NRD-545, JRC NRD-525, FRT-7700, RTLSDR F0013, 40m of wire @ 8m, vertical whip on @ 7m

Offline Dag

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Re: Mystery signal question
« Reply #47 on: October 13, 2015, 2351 UTC »
Oh my! I'm so glad to see this thread -- I've heard these signals for decades as well wondering what they are.

The analysis and speculation is very interesting and alas, I can shed no light on these mysterious signals.

I am listening to a repetitive sweeper on 14414.50 KHz. It "sweeps" about every 7 seconds for about 9 repetitions, but now it's fading a bit.

Dag
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Offline ulx2

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Re: Mystery signal question
« Reply #48 on: October 14, 2015, 1537 UTC »
Hello.

I guess, these signals have rather semi-natural origin.

Such phenomena could be produced e.g. by some kind of non-linear processes of interaction of meteor traces (or some other mobile objects?) with man-made radio signals. The frequency drift can be explained by Doppler effect. Are the results of observations correlating with meteor activity?
« Last Edit: October 14, 2015, 2211 UTC by ulx2 »
LOC: Kyiv, Ukraine
RX1: Degen DE-1103 portable
RX2: Xhdata D-808 portable
RX3: Airspy Mini SDR + Spyverter
ANT1: 80 mb dipole
ANT2: Long wire (10 meters)
ANT3: Homemade M0AYF active loop
ACC: Homemade passive preselector & phasing device

https://udxb.blogspot.com/

Offline ChrisSmolinski

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Re: Mystery signal question
« Reply #49 on: October 14, 2015, 1728 UTC »
I'm seeing a few sliders this afternoon, but not as many as some days. Checking just above 16 MHz now.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline Token

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Re: Mystery signal question
« Reply #50 on: October 15, 2015, 2152 UTC »
Hello.

I guess, these signals have rather semi-natural origin.

Such phenomena could be produced e.g. by some kind of non-linear processes of interaction of meteor traces (or some other mobile objects?) with man-made radio signals. The frequency drift can be explained by Doppler effect. Are the results of observations correlating with meteor activity?

These are probably not going to be natural phenomena.  As discussed on page 3 of this thread there is significantly less activity on any given Sunday.  I plotted this over a period of 6 weeks, every day, and without fail the activity of these sweepers was a lot less on Sunday than any other day of the week.  Typically the Sunday level of activity was 1/10, or less, of the activity any other day.

Even if they were natural they would not be meteor related.  Looking at the following image if each of these sweepers were a meteor we would be talking rates approaching 1000 meteors an hour for hours on end.  Such a meteor storm would be quite an event…and the events in this image can happen every day for weeks on end as long as propagation is supportive.  As a reference, the Leonids Meteor Shower for this year is predicted to produce about 25 or less meteors per hour at its peak.



A larger, and more detailed, shot of the above is here:
http://www.pbase.com/token/image/158277017/original.jpg

Could this be a reflection of some signal with Doppler?  Unlikely.  First of all we never really see a candidate RF source, and that seems a bit odd, but there are also other reasons.

Look at this image:


That image is either of one or two sweepers, I think it is just one with a step or change of direction in it (because every time seen they are locked in reference to each other), but lets treat it as two, this results in lower numbers.  The frequency is roughly 28300 kHz, and the swept width of just the longer section is a bit over 250 kHz.  To cause a just over 250 kHz Doppler at around 28300 kHz would require an item changing radial velocity relative to the RF source by about 95000 km/h in the 11 seconds of that curve.  Sure, some meteors can travel in excess of that rate, but little else near or on Earth does, and I think I have already given a fair argument for it not being meteors.


In that image also note the rough texture of the sweep.  Many of the sweepers have this and some are much more pronounced than in that image.  This texture would have to equate to either changing Doppler for some reason or changing source RF.  Doppler changing that rapidly would mean extremely fast and repeating changes in velocity, either at the signal source or the object causing the reflection.  If we consider again a meteor as the source it would have to be accelerating and decelerating radially relative to the source of RF, as far as I know a meteor will not do anything remotely like that.  And as I said before, once you have eliminated a meteor as having anything to do with this signal few other things could have velocity changes on the order required for this to be Doppler.


T!
« Last Edit: October 16, 2015, 1612 UTC by Token »
T!
Mojave Desert, California USA

Offline Cornel

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Re: Mystery signal question
« Reply #51 on: October 27, 2015, 1328 UTC »
Monday 26.10.2015 24000kHz-25000kHz, RTLSDR , ~14:00 local, first time i see this long sweep with interruptions and almost vertical termination.
Cordoba, Argentina.
JRC NRD-545, JRC NRD-525, FRT-7700, RTLSDR F0013, 40m of wire @ 8m, vertical whip on @ 7m

Offline Cornel

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Re: Mystery signal question
« Reply #52 on: October 27, 2015, 1334 UTC »
New sweeper more detailed

Edit: After further study it seems that the horizontal sweep has nothing to do with the other.
« Last Edit: October 27, 2015, 1949 UTC by Cornel »
Cordoba, Argentina.
JRC NRD-545, JRC NRD-525, FRT-7700, RTLSDR F0013, 40m of wire @ 8m, vertical whip on @ 7m

Offline Cornel

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Re: Mystery signal question
« Reply #53 on: October 27, 2015, 2108 UTC »
Other observation today:

16:30z (13:30art) Overcast, no rain, no thunder.


17:50z Things are getting funky. Winds with humid and warm air from north, thunderstorms closing up.



17:53z Rain, Thunderstorm



19:10z Storm is over, no wind

In this last shot there is also an interesting 11:11  'up-sweeper to down-sweeper' ratio.

(How) Does weather influence the propagation of the sweepers?  :o
« Last Edit: October 27, 2015, 2138 UTC by Cornel »
Cordoba, Argentina.
JRC NRD-545, JRC NRD-525, FRT-7700, RTLSDR F0013, 40m of wire @ 8m, vertical whip on @ 7m

Offline ChrisSmolinski

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Re: Mystery signal question
« Reply #54 on: October 17, 2016, 1520 UTC »
We've not talked about sliders recently, so I figured I would check and see if they were still around, and indeed they are. Seeing a few in the 24-26 MHz at 1520z on 17 Oct 2016.
Chris Smolinski
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netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 400 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

Offline Token

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Re: Mystery signal question
« Reply #55 on: October 19, 2016, 0158 UTC »
I see them every day, from 13 MHz up, and sometimes below that.  Definitely see more when propagation conditions are good.  When 10 meters is open to Asia I still see the band blasted by them.

T!
T!
Mojave Desert, California USA

Offline ulx2

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Re: Mystery signal question
« Reply #56 on: October 20, 2016, 2136 UTC »
Thanks for the detailed reply, Token.

I see them every day, from 13 MHz up, and sometimes below that.

It's interesting, what are the highest frequencies where they can be observed?
LOC: Kyiv, Ukraine
RX1: Degen DE-1103 portable
RX2: Xhdata D-808 portable
RX3: Airspy Mini SDR + Spyverter
ANT1: 80 mb dipole
ANT2: Long wire (10 meters)
ANT3: Homemade M0AYF active loop
ACC: Homemade passive preselector & phasing device

https://udxb.blogspot.com/

Offline Josh

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Re: Mystery signal question
« Reply #57 on: November 05, 2016, 1453 UTC »
Jupiter or Saturn make noises in that range but I don't think they look like that in a spectrogram. Also, the planet would have to be viewable to the receiver as in line of sight.

http://www.spacetoday.org/SolSys/Jupiter/JupiterRadio.html
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Offline Token

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Re: Mystery signal question
« Reply #58 on: November 06, 2016, 0130 UTC »
Yeah, Saturn and Jupiter have been ruled out for this.

T!
T!
Mojave Desert, California USA

Offline ulx2

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Re: Mystery signal question
« Reply #59 on: November 13, 2016, 2325 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?
« Last Edit: November 14, 2016, 0004 UTC by ulx2 »
LOC: Kyiv, Ukraine
RX1: Degen DE-1103 portable
RX2: Xhdata D-808 portable
RX3: Airspy Mini SDR + Spyverter
ANT1: 80 mb dipole
ANT2: Long wire (10 meters)
ANT3: Homemade M0AYF active loop
ACC: Homemade passive preselector & phasing device

https://udxb.blogspot.com/