HFU HF Underground
Loggings => HF Mystery Signals => Topic started by: jcwilshire on September 12, 2013, 1434 UTC
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Can anyone identify the attached mystery signal?
I've personally observed it only in the 11 meter citizen's band, though that doesn't mean I'm saying it never happens elsewhere. I often see it between 27.0 - 27.3 MHz, and only when skip/propagation is in.
It has been happening for decades (earliest memory: late 1980s).
It can be received with tuners in both Europe and North America (and possibly other locations).
I first assumed it was an ionosonde, but now have doubts because:
1) Instead of a sinewave (like an ionosonde), it consists of a "warbly" up-down-up-down sweep tone.
2) That warbling tone itself descends in frequency (rather than ascending, as normal chipsounders do).
3) And it only descends 40-50 kHz. I.e., it begins instantly (no fade-in), descends 40-50 kHz, then stops instantly (no fade out).
Here are several audio samples of it, edited together. Note that I used Twente's WebSDR in DSB reception mode. That allows it to be heard as it sounds when crossing through AM carriers.
http://s000.tinyupload.com/index.php?file_id=93766677053675299202
Finally, I should note that there appear to be two variations of this mystery signal:
Variation 1: Same as pictured above. While observing it yesterday, it always lasted 4 seconds, and then reoccured every 13 seconds. With this variation, the rate of frequency descent slows just before the signal vanishes (i.e., you see a diagonal line slowly curve into a vertical line). Sometimes, the signal even reverses direction (goes back up in frequency) just before vanishing.
Variation 2: This variation always lasts about 15 seconds (i.e., it descends in frequency much more slowly). Unlike the first variation, its rate of descent does not slow before the signal vanishes, nor does it reverse direction and go back up. Therefore it always appears as a diagonal line on waterfalls. This variation also has a longer duration between occurences (30 to 60 seconds, guessing). Nonetheless, it sounds audible exactly the same as the first variation when it passes through your receiver's IF (same warbling sweep effect).
Any ideas?
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I've heard that since the 1970's on the CB bands.
27MHz contains the most used ISM band in the world and it could be anything from dielectric heating to laboratory RF pumps.
Peace!
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In the beginning of the recording, it sounds like my old APC UPS on 15 MHz (until I pulled it out of service on Tues as got sick of that). However, the later noises don't sound like it.
Like cmradio said, could be just about anything.
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Your post reminded me of this screen cap I took last May 22 at 2200 utc.
While I have noticed a few of these from time to time - May 22nd I was "seeing" remarkable clusters of the same.
They persisted for about a 1/2 hour then were gone??
I seem to remember there were some rather energetic sun spots at the time?? Just guessing?
The horizontal lines were from utility noise I was suffering last late winter into spring.
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Fascinating, Rockpicker. I'm also surprised that nobody really seems to know what causes these anomalies.
Anyway, I might have another clue to offer, one observed just minutes ago. I spotted what appears to be the same signal phenomenon, only this time in the middle of HF band. The only difference: the signal was not sweeping down or up in frequency. It was completely stationary. Furthermore, there were at least twenty iterations of it, evenly spaced across 2.6 MHz of spectrum. Some screen captures (they go from high zoom to a wide view, and in the final image, you can see the signal's numerous iterations spanning approximately 5575 to 8200 kHz):
http://i.imgur.com/fsQFKDZ.png
http://i.imgur.com/Eypbmkt.png
http://i.imgur.com/o7j7xUF.png
http://i.imgur.com/eZopdUq.png
And to my ears, it does sound like the same phenomenon as on 27-28 MHz. It may not be immediately apparent (because of it not sweeping through the receiver's IF), but to me, it has the same warbly/fluttery sonic signature. Recording (two instances back-to-back): http://s000.tinyupload.com/index.php?file_id=07301278353252032862
Incidentally, I went up to 27 MHz upon noticing this, and sure enough, the phenomenon was happening there simultaneously (only there, in the same sweeping form I described earlier):
http://i.imgur.com/LKYxruz.png
http://i.imgur.com/5zyMQg7.png
http://i.imgur.com/vpe5b1z.png
http://i.imgur.com/uYCHxab.png
Sure would be nice to figure out what this thing is!
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Some of those signals look like local RFI. I've seen similar things here when various electronic devices were switched on. Most today use switching power supplies, and the switching frequency is rarely stable, it drifts, often a lot, especially just after power on. And you get harmonics well up into the upper end of HF.
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I was testing an antenna this AM, and I began to note something very much like this. The entire duration of the period I noted this was only about 5 minutes.
(http://i1049.photobucket.com/albums/s387/jFarley44/Screenshot-2013-09-20-082135_zps19789f0d.png) (http://s1049.photobucket.com/user/jFarley44/media/Screenshot-2013-09-20-082135_zps19789f0d.png.html)
Spacing between the events was variable 30 to 40 seconds, and the termination frequencies tightly scattered around 15798 +/- 8 kHz. It went off (or stopped) before I could examine the top end of the slide.
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Again testing an antenna, I noted carrier coming and going on 15475 (LRA36?) and checked the Twente SDR for comparison (also weak carrier there). I noted these hooks weakly on the Twente rig with terminal frequencies around 15490 kHz for a few minutes around 1900z. They were not noted here in Chicago.
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Seconds ago, I noted a hook on 15666 - been seeing them pop up all over the place here in the UK
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My old cell phone charger used to do a rhythmic warbling thing lasting 5-10 seconds per cycle until it was charged. Sounded somewhat similar to the file in the first post. Radio had to be less than 10 feet away tho.
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Yeah, a power supply or charger always a suspect. Test antenna was about 30 feet from the house. Hooks also seen at same time on a Wellbrook about 100 feet away from any home. Dunno, but interesting.
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Ive been hearing that same thing for years ive got no idea what it is though.Theres also one usually above cb 1-40 youll here beep beep beep brawwwwwwwwww lasts about three seconds then gone,have no idea what is either.
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Ive been hearing that same thing for years ive got no idea what it is though.Theres also one usually above cb 1-40 youll here beep beep beep brawwwwwwwwww lasts about three seconds then gone,have no idea what is either.
If it's on 27.255, that's an ancient Radio Shack alarm.
Local fella had it on his boat, didn't even know it (bought it second hand). Made a racket for years! :D
Peace!
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hehe no its not on 27.255 it moves around i hear it off and on no matter where im at.
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Hi All,
I have heard this since the late 1960's and I have no idea at to what it is but I have parked a receiver on a 'clear' frequency and used this sound to let me know of band openings in this area of frequencies.
There is also one on HF I have used as an indicator of band conditions and it is simply kinda sorta like the sound of a VFO quickly sweeping across the frequency. In fact I just heard one on 18127khz as I am writing this. These types of 'sweeper' is seldom very strong but if you hear them it does indicate the band is open. I have never heard them when the band is 'dead'
The 'WAV' file provided brings back memories of some of the first BJT VFO's I made in the early days... <heh> kinda like the Timtron's 'wabble-a-tor' transmitter... but that's quite another story ;-)
73 Vince
KA1IIC
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The sweeper that you hear is probably an ionosonde.
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I'm almost positive that these cannot be ionosondes. The ones which appear in the 10-11 meter range only sweep 30-40 kHz of spectrum, as originally mentioned. But now that I am actively looking, I am noticing that the ones appearing throughout the lower HF bands almost always remain on one frequency, each drifting possibly only 2-3 kHz over a period of minutes. For example, as I write this, the 20 meter ham band is currently crawling with the things. See first attachment (and second attachment for a close-up of one).
In any case, everybody seems to have verified that, as with my experiences, they only appear during skip. So that also rules out sources of local RFI.
Edit: Would you or another moderator mind downloading the tinyupload.com sound files in my first and second posts, and attaching them to their respective posts (despite the attachment limits that apply to us mere users)? I'd hate to think that somebody who knows the definitive explanation for these sounds might stumble across this forum in 9 months, only to find expired file locker links. Many thanks.
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For example, as I write this, the 20 meter ham band is currently crawling with the things.
OK, that is completely new to me and isn't an ISM band and would be rediculous for dielectric heating.
Having heard then on 11M since forever, I too would really like to know what they are.
Peace!
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Just dropping in to confirm that I have also heard this exact sound many times on the CB band.
Even when monitoring 27.185 when skip is strong I have noticed it, sometimes so strong that it wipes out DX for the short time it is on.
Always wondered what it was myself but never thought to question it.
Interesting how it is noted as far back as the 1960s here. That kind of rules out modern device RFI. Also the fact that it only happens during skip means whatever it is must be radiating really well to be heard by so many people across so many frequencies.
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Spotting more occurrences tonight on HF. And here are some examples I encountered on 20 meters again, but this time quite strong, and also with a very slow warble frequency -- slow enough that with the WebSDR waterfall in fast mode, the warble is perfectly detailed visually.
http://i.imgur.com/O2Rx9oc.png
http://i.imgur.com/2dfq8Pu.png
http://i.imgur.com/1a1miy8.png
http://i.imgur.com/TEMTikP.png
Recording of two of them, as they pass from top to bottom through the WebSDR's 6 kHz wide USB IF: http://s000.tinyupload.com/index.php?file_id=09570432523318839701
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caught these today on 27700u been going off and on for awhile this is the sounds i hear most often
https://archive.org/details/27700uOct142013StrangeSounds
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I think we ALL heard these one or more times and since years. Here in Argentina i can monitor them daily on various frequencies, say 8-30MHz, and allways strong to vy strong. I my case i think http://ionos.ingv.it/tucuman/fplotMUF.html guys are xmiting the sigs. It would be interesting to know if that mode was also used in 1960s (and up). They xmit regardless of bandlimits etc. Signal sounds/looks scientific to me, not RFI. check ionos.ingv.net.
cheers
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Yes, I have heard these for decades on HF, many people have, but I think the wide spread use of waterfall displays have made them more obvious to listeners.
I am very certain these are not ionosondes of any kind. First, the signals are far to narrow banded to be useful ionosondes, even if you look at all of them as coming from one source you end up with too many gaps. Second, most ionosondes are well documented, as are their waveforms. In the case of the ionos.ingv.it sondes and plots Cornel posted, that source uses the INS-INGV ionosonde. Descriptions of the waveforms 16 bit complementary phase code can be found online…and it does not look like these things, and I think that one tops out at 20 MHz. No documented ionosonde has a waveform even remotely resembling these.
As for what they may be, I have no idea. I did once show an image of the signal to an engineer working with RF Induction heating, and he said they look something like what can be seen as a result of a low duty cycle pulsed RF Induction heating source, however he also said those are typically found below 4 MHz.
In my opinion they look incoherent and random with regard to amplitude and phase content. I think that makes them unlikely to be intentional transmissions other than byproducts of some operation / hardware. There is NO doubt they are fairly high power, I have received the same single transmission on multiple remotes located hundreds or thousands of miles apart before, but realistically that kind might be possible with fairly modest power levels. It does not take thousands of Watts, but only hundreds or maybe even tens.
T!
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Thanks T. Interesting. I think i need a SDR :).
Soooo, why do we hear these sigs all over the world? Do they appear random, frequencie/time/direction wise? Maybe something "secret", undocumented.
I think we all agree it's not "mother nature" doing these. If it's just some RF garbage from inductive soldering or any other industrial action, why nobody complains cos of this RFI? I mean, if somebody does RFI over hundereds even thousands of miles, that would lead to investigation at least. No?
Do we hear these in the, lets say, MWARA/safety ranges of HF? What does the FCC/ITU say to this mistery? RFI is RFI. isn't it? If the source is industrial, then it must be an old "fashioned" process(es), we hear it since decades, and even today.
Strange indeed.
Only more questions, no answers.
C
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I know this is an old post but it reminds me of a powerful signal that used to sweep 11 meters back in the 70s. I remember a "sweeping carrier" that would peg the needle on my friend's Johnson Messenger 223 tube set. Sometimes it would last several seconds and wipe out 11 meters and was extremely frustrating. We lived in a small town in Pennsylvania (Kelayres) and my friend lived in the adjoining town (McAdoo). We suspected it was an unintended electrical signal associated with some type of switching equipment from a local clothing manufacturing plant (McAdoo MFG). It was only present during the day although the plant used to stay open until 2100 at reduced activity. It went away some time a decade later which probably was the result of a repair or replacement of whatever was causing the problem. It was never reported to the FCC as far as I know. I do not think it was atmospheric but localized. After I joined the USAF, I would visit home when I could in between PCS moves and always had access to 11 meters plus a general coverage receiver and it never returned.
Just out of curiosity, if the audio file is still available, please provide a new link. The other link has expired. I would like to hear what the signal reported in this message sounds like.
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I think we all agree it's not "mother nature" doing these. If it's just some RF garbage from inductive soldering or any other industrial action, why nobody complains cos of this RFI? I mean, if somebody does RFI over hundereds even thousands of miles, that would lead to investigation at least. No?
Do we hear these in the, lets say, MWARA/safety ranges of HF? What does the FCC/ITU say to this mistery? RFI is RFI. isn't it? If the source is industrial, then it must be an old "fashioned" process(es), we hear it since decades, and even today.
At one time or another I think I have heard these on almost any frequency band, however they do tend to appear in a few more commonly than others. Right now I am watching two hitting the 13150 kHz area, half a dozen hitting the 14400 to 15000 kHz area, and dozens from 26000 to 32000 kHz. 28400 to 30000 seem to be most densely populated.
It might be worth noting that those bands I just mentioned could be harmonically related. Could this be some lower freq industrial RFI, say below 4 MHz, and we are seeing the harmonics when band conditions allow? I have tried to match some lower freq sweeps to higher freq ones, to prove the harmonic relationship, so far unsuccessfully.
T!
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Would it be useful for as many of us as possible to check for these things, and post in real time when they are observed (IRC might be best). Then if folks could check sub-harmonic frequencies, we might be able to find the fundamental and general location, if someone is lucky enough to be nearby the transmitting source.
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It seems as if we are all dumbfounded by these events. I do believe that there may indeed be a terrestrial source for these bursts, and that's it. Badda bing, badda boom. But lately, I have been wondering if the source may be somewhere else. Has it ever been suggested that we might be seeing radio bursts from, let's say, Jupiter?
http://science.nasa.gov/science-news/science-at-nasa/2000/radiojove_sbursts/
There is a lot of similarity between these Jovian S-Bursts and the emissions we are observing. Maybe while we are checking for sub-harmonics we might also keep track of Jovian declination and ascension.
Is there an astronomer in the house?
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I'm picking up some of these now, jFarley, right around 15900 kHz.
Interesting theory - Jupiter. I tried some time ago to listen to Jupiter but was never able to. I did write a prediction program for the radio bursts, let me dig it up and see what it shows for now.
I'll check on IRC and see if anyone else is picking these up.
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OK seeing a couple now.
The theory might be easier to disprove than prove?
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I checked, and there are no Jupiter radio storms predicted for now.
Here is what I am seeing now:
(http://www.radiohobbyist.org/blog/mypics/16mhzoddsignal.jpg)
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I checked, and there are no Jupiter radio storms predicted for now.
Oh well; would have been a tough QSL anyway...
Saw some unusual things today:
(http://i1049.photobucket.com/albums/s387/jFarley44/Screenshot-2014-11-13-151148_zps80c768b5.png) (http://s1049.photobucket.com/user/jFarley44/media/Screenshot-2014-11-13-151148_zps80c768b5.png.html)
I have never seen the degree of "flaring out" near decay as seen today in the 2 on the right. In between is one which seems to slow down its descent in frequency, and then descend some more. A couple I saw today had a very pronounced reverse S curve.
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J, the flare at the end is a common feature seen here. Also the shape can go back and forth, have seen them reverse, even make hard corners.
T!
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Thanks T!
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Can't hear the sound files that were posted earlier in this thread, since they've apparently been deleted, but if it sounds like a type of warbly squish noise it's probably Jupiter.
I remember reading about it in the 1990's in PopComm or Monitoring Times.
I've heard the noise usually above 20 mhz, both in the CB band, and near that part of the HF spectrum.
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This may mean something, or it may not.
Today the bands are not quite as good as they have been all week long, however they are not in bad shape, 10 meters, for example, is packed. Because there had been a request for a recording I stopped by the band several times to grab a recording of these signals to post to my Youtube channel. However basically I am not seeing any of these signals today. One or two stragglers, but nothing like the density of yesterday and the preceding 5 days.
Today is Sunday, and if these signals are byproducts of an industrial process might you be able to expect lighter traffic on Sunday in most nations?
Right this minute I see zero of these signals in the 10 meter band, or in any other band, but yesterday there were dozens visible at any one time. I have seen a few of them today, but really VERY few. I am thinking that can't all be conditions.
T!
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Now Monday morning, 1500 UTC, and I see these signals are back in normal numbers.
10800 to 11300 I see a couple per minute, 14600 to 15000 I see maybe 6 to 8 per minute, 16800 to 17200 I see maybe one every 20 seconds, 23050 to 23250 I am seeing a couple per minute, 28000 to 29000 I see dozens per minute, 37250 to 37750 I see 8 or 9 per minute. I do see them in a few other frequency ranges, but those seem to be the most consistent.
I have scheduled 2 recordings a day to try and see if there is a daily cycle involved (i.e. was Sundays absence real or not). I have a 1 MHz wide chunk of spectrum centered on 14500 and 28500 kHz scheduled for 1 minute every day at about 1500 UTC. If I get around to it I want to log the number of sweepers seen in that 1 minute / 1 MHz chunk daily to see what the trends are.
As for Jupiter as a source, I think probably not. These signals do not match either L bursts or S bursts from Jupiter. They are too fast and narrow banded for L bursts, and the bandwidth is right for S burst but they are too slow.
Also, these signals do not seem to have any timing in common for when Jupiter is above the horizon or not. I would think that if they were from Jupiter they would be more likely to be seen when Jupiter is above the horizon, and less when it was below, instead these signals seem to be tied to propagation conditions, strongly suggesting, to me, that they are terrestrial. I would think that the same factors that make propagation good (radio wave reflections off charged portions of the ionosphere) would also make those bands less likely to show Jovian noise, since the signal from Jupiter would have to penetrate that layer.
(edit) Interesting, in setting up the recordings I decided to use a directional antenna. I found that the 10 meter sweepers are mostly coming from a different direction than the ones near 20 meters.
T!
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Good points all, T, and those last two sentences in particular are interesting... The case for a terrestrial source is indeed compelling.
I just have problems understanding the nature of the source, and why we are seeing these. What sort of physical plant could be generating these decametric emissions? Are the emissions themselves the process? Are these leakages or spurious emissions?
Why do we see multiple simultaneous events as in the following?
(http://i1049.photobucket.com/albums/s387/jFarley44/Screenshot-2014-11-13-145842_zps238e7847.png) (http://s1049.photobucket.com/user/jFarley44/media/Screenshot-2014-11-13-145842_zps238e7847.png.html)
Got me hanging!
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I'm seeing a few around 16 MHz right now. Nothing else noted here, but I didn't try for long, time to set up for recording 6800-7000 kHz :-)
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As I said in my previous post, they appear to be from different directions, although so far the ones in a given frequency range seem to be from the same direction. I would be real careful with that thought though, the data set is pretty small to start drawing conclusions. In my notes I am saying "potential".
Examples below.
The first image is a 600 kHz wide shot centered on 14700 kHz. Often I have more sweepers than this in this range, but you take what propagation gives you. Note the two different sweepers near 14560 kHz. This image was taken with the antenna pointed at 320 degrees true.
(http://www.pbase.com/token/image/158271673/large.jpg)
The next image was taken with identical settings, one minute after the one above, but with the antenna pointed 140 degrees true. Note the sweepers near 14560 kHz are not seen, however another one with a different shape is seen around 14580 kHz.
(http://www.pbase.com/token/image/158271676/large.jpg)
This next image is a 1000 kHz wide shot centered on 28500 kHz. The antenna is pointed 140 degrees true. Note how many, and how strong, the sweepers are.
(http://www.pbase.com/token/image/158271670/large.jpg)
And the next image is the same 1000 kHz wide spectrum centered on 28500 kHz, however now taken with the antenna pointed 320 degrees true. Notice how many fewer sweepers are seen, and some of the ones that are seen are different from the 140 degree shot.
(http://www.pbase.com/token/image/158271667/large.jpg)
So for me, at this time, it looks like the strongest 10 meter sweepers are from the south east, and the strongest 20'ish meter sweepers are from the north west. It appears to have been that way for the last 6+ hours.
T!
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24 MHz is quite active at around 1320z.
16 MHz is also busy.
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40 minutes after my post last night, with 4 pictures from 2 directions, 10 meters to the east closed down, and Asian stations started rolling in on 10 meters. Then the sweepers from the north west on 10 really started coming in.
1.6 MHz wide span centered on 29240 kHz, antenna pointed 320 degrees true. This is towards China for me, although naturally there are other nations along the same bearing.
(http://www.pbase.com/token/image/158277017/large.jpg)
A larger, and more detailed, shot of the above is here:
http://www.pbase.com/token/image/158277017/original.jpg
T!
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OK, no doubt, two Sundays in a row now there has been SIGNIFICANTLY reduced sweeper activity on Sunday vs any other day of the week. I did not notice any particular reduction on Saturday.
To check the activity for the last week I have been recording a 1 MHz wide piece of spectrum, centered on 28500 kHz, every day at 1702 UTC. Last Sunday and this Sunday there was greatly reduced sweeper traffic in this range.
The image below is the week day with the least amount of sweeper activity, the lowest count per minute of sweepers in 1 MHz during the recorded minute. This was Friday morning. Note that in this one minute time there are over 80 sweepers seen, typically on weekdays at this time I am seeing between 80 and 140 sweepers per minute.
(http://www.pbase.com/token/image/158330176/large.jpg)
A larger version of this image, more detail, can be seen here:
http://www.pbase.com/token/image/158330176/original.jpg
This morning in the same one minute period (1702 UTC, 28500 kHz center frequency, 1 MHz total width) I saw 6 sweepers in one minute. Unfortunately the recording was corrupted for some reason (DOH!) so I had to remake it, and I did not do that until 2043 UTC. So the image below is form 2043 UTC, not 1702 UTC. However, it actually shows more sweepers than I saw at 1702 UTC when I counted them live. This one has 9 or 10 visible.
(http://www.pbase.com/token/image/158330280/large.jpg)
Larger version of this image here:
http://www.pbase.com/token/image/158330280/original.jpg
On the surface of things I would say whatever generates the sweepers is an activity that is greatly reduced on Sundays. That would argue strongly against natural phenomena, since few of them take Sundays off ;)
T!
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40 minutes after my post last night, with 4 pictures from 2 directions, 10 meters to the east closed down, and Asian stations started rolling in on 10 meters. Then the sweepers from the north west on 10 really started coming in.
1.6 MHz wide span centered on 29240 kHz, antenna pointed 320 degrees true. This is towards China for me, although naturally there are other nations along the same bearing.
(http://www.pbase.com/token/image/158277017/large.jpg)
If I'd have seen that before seeing it here, I'd probably have fallen out of my chair. Never seen anything like it on my SDR. :o
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Edit: Would you or another moderator mind downloading the tinyupload.com sound files in my first and second posts, and attaching them to their respective posts (despite the attachment limits that apply to us mere users)? I'd hate to think that somebody who knows the definitive explanation for these sounds might stumble across this forum in 9 months, only to find expired file locker links. Many thanks.
Can't hear the sound files that were posted earlier in this thread, since they've apparently been deleted, [...]
Welp.
Time to repeat my request, I suppose. SMF administrators can override maximum attachment size limitations, if memory serves. So can one of you please preserve these as attachments to my original posts? Here they are again:
From my September 12 post: http://s000.tinyupload.com/index.php?file_id=07669869441791435247
From my September 19 post: http://s000.tinyupload.com/index.php?file_id=32944569909504757660
From my September 29 post: http://s000.tinyupload.com/index.php?file_id=04057650744254842337
P.S. Glad to see this thread still going. Very interesting findings lately as well. In particular, the waterfall OldSeaRock is quoting in the post immediately preceeding this one is astounding. From the looks of it, it almost appears that the band needs to be de-wormed! Maybe that's the nickname these things should be given. "Screaming worms." Screaming because they're audible worldwide, and worms because of how they appear on spectral graphs. ;) Anyway. I hope the explanation will someday be found.
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Today ~18:00z 24000-25000, RTL SDR F0013. They live!
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...and sunday 11.10.2015 the same range 24000-25000kHz, ~18:00z
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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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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?
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I'm seeing a few sliders this afternoon, but not as many as some days. Checking just above 16 MHz now.
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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.
(http://www.pbase.com/token/image/158277017/large.jpg)
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:
(http://www.pbase.com/token/image/139079178/large.jpg)
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!
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Monday 26.10.2015 24000kHz-25000kHz, RTLSDR , ~14:00 local, first time i see this long sweep with interruptions and almost vertical termination.
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New sweeper more detailed
Edit: After further study it seems that the horizontal sweep has nothing to do with the other.
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Other observation today:
16:30z (13:30art) Overcast, no rain, no thunder.
(http://i.imgur.com/m1DUR5h.jpg)
17:50z Things are getting funky. Winds with humid and warm air from north, thunderstorms closing up.
(http://i.imgur.com/fYOF5OV.jpg)
(http://i.imgur.com/GUG4jlo.jpg)
17:53z Rain, Thunderstorm
(http://i.imgur.com/tb6WN5o.jpg)
19:10z Storm is over, no wind
(http://i.imgur.com/ZmEPGhe.jpg)
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
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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.
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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!
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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?
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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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Yeah, Saturn and Jupiter have been ruled out for this.
T!
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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?
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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!
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I think the Aricebo HF transmitter is 0.6 MW, not 6 MW
6 MW is EIRP, I guess.
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.
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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.
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!
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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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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!
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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
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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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I'm recording the 73m band for pirates now, and last night noticed some of our sliders around 0700 UTC:
(https://i.imgur.com/Iddm72a.jpg)