Strange whistler like signals found on 15-29 MHz iq file included...

quazar32

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Does anyone know what these are? They are like whistlers but are on higher frequencies. They only come in when daytime skip is present, and very in frequency / intensity, and have fade. Did some searching but so far nothing?

IQ file...

13-45-05_27160000Hz.wav

The Iq file was recorded in December if that means anything?
 

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Token

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Does anyone know what these are? They are like whistlers but are on higher frequencies. They only come in when daytime skip is present, and very in frequency / intensity, and have fade. Did some searching but so far nothing?

IQ file...

13-45-05_27160000Hz.wav

The Iq file was recorded in December if that means anything?

I call these "hooks" or "sweepers". I have heard them for decades, but the proliferation of waterfalls in hobby use make them much more evident.

These signals are often attributed to industrial processes, such as RF welding. I can say for sure I have looked at several pieces of RF welding gear and can confirm that, in operation, they do emit signals similar to those. It is often tempting to say "yeah, but how big a signal should an industrial process make?" Keep in mind that many of these kinds of welders run to 10's of kW of welding power.

In the US the welders might have pretty tight specifications to meet. However, I have noticed that when the skip is in from various locations, Asia and South America, I can turn my beam in those directions and see many, many, more of these signals over a much wider range of frequencies.

First set of two images taken when skip was in to South America. The second set of two images were taken when the skip was in to Asia.

Here is an image with the antenna pointed 320 degrees, away from South America. South American skip was in at the time, but my antenna is pointed away from South America, about 320 degrees true.
158271667.RKDzAPVJ.Sweepers_28500_320deg_11172014_2242.jpg


Here is an image take 2 minutes earlier, with the antenna pointed towards South America, about 140 degrees true. You can see that the sweepers are much stronger and more numerous.
158271670.h4vrUvtg.Sweepers_28500_140deg_11172014_2240.jpg



Below is a different set, on a different day, taken when the skip was in from Asia. The first image is taken with the antenna pointed away from Asia, at about 140 degrees true.
158277016.rm7NdCxi.Sweepers_28500_140deg_11182014_0007.jpg


The second image is with the antenna pointed towards Asia, about 320 degrees true.
158277015.Pn8jaVYW.Sweepers_28500_320deg_11182014_0006.jpg


T!
 
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mmckenna

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Sort of related….
When I was in High School, the wood shop class had a "Wood Welder". I only saw it used once. It was a big box in the back that used a strong RF field to heat up a glue to "weld" the wood together. It used a substantial amount of power. Probably 220v at 50 amps.

It had a old faded FCC license on the side of it. I wish I could recall what frequency it was, I want to say it was something in the 27MHz range, but it was a long time ago.

Anyway, a big RF generator, probably a few hundred watts at least, maybe more based on the size of the AC power feed.

A much older version than this:
RF Wood Welder | Radio Frequency Welder | JYC 1.5KW at 27.12MHz.
 

majoco

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At any time of the day when there are good reception conditions, if you have a good receiver with quite a wide waterfall display you will see these 'sweepers' as a line across the display and hear them on SSB or CW. I believe that they are atmospheric sounders
 

mancow

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At any time of the day when there are good reception conditions, if you have a good receiver with quite a wide waterfall display you will see these 'sweepers' as a line across the display and hear them on SSB or CW. I believe that they are atmospheric sounders
Those go from low to high frequency in a linear fashion. These are varied and start high going low as if the source is being loaded down as it operates, as in HF welding.
 

Token

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Those go from low to high frequency in a linear fashion.

As an aside, chirpsounders (at least the model I examined) can be set to go from high to low also, but I don't think I have ever seen one sued that way.

These are varied and start high going low as if the source is being loaded down as it operates, as in HF welding.

My theory, and I freely admit it is just a guess, is that as the material heats up the inductance and capacitance changes, causing that frequency shift.

T!
 

wx2watch

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As an aside, chirpsounders (at least the model I examined) can be set to go from high to low also, but I don't think I have ever seen one sued that way.



My theory, and I freely admit it is just a guess, is that as the material heats up the inductance and capacitance changes, causing that frequency shift.

T!
For whatever reason, my computer will not give me any audio from the wav file so I put this idea out there as a SWAG - Maybe these are HF radio emissions from the planet Jupiter? (Long time ago I was familiar with something called Radio Jove; a NASA educational program.)
 

Token

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For whatever reason, my computer will not give me any audio from the wav file so I put this idea out there as a SWAG - Maybe these are HF radio emissions from the planet Jupiter? (Long time ago I was familiar with something called Radio Jove; a NASA educational program.)

No, the Jovian emissions are very different from these.

T!
 

merlin

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While I can see RF welders doing this, if you live near a hospital, some medical imaging equipment uses the same ISM bands. Weak, but shows up on my spectrum analyzer.
 

quazar32

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Ok, based on what you have told me; I watched this weekend. My theory was if it was man made the activity would decrease during the weekend. It did! Especially on Sunday when 10 meters was going crazy. Today, Monday the activity increased with them all over as usual.

Also you led me to this - 27 MHz ISM Fish Hook Swisher Interference RFI EMI RF HF Sealers Heaters Welders

You can't really see a lot of them zoomed out at 10Mhz wide, but at 2Mhz there are lots of them all over.

I would say Token is 100% correct.
 

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Token

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Ok, based on what you have told me; I watched this weekend. My theory was if it was man made the activity would decrease during the weekend. It did! Especially on Sunday when 10 meters was going crazy. Today, Monday the activity increased with them all over as usual.

Also you led me to this - 27 MHz ISM Fish Hook Swisher Interference RFI EMI RF HF Sealers Heaters Welders

If you search HFU a little more you will see a post there (different thread than the one you posted) that says the same thing. I repeatedly found them to be less numerus on Sunday than any other day. Found the post here: Mystery signal question In the end I recorded every Sunday for several months, and consistently saw significant reduction in the Hook / Sweeper activities on Sunday, even when the band was open and very active.

There are a dozen or so threads on HFU on this subject over the past 12 or so years and I remember discussions in newsgroups 20+ years ago on the same subject.

Of interest to me is the fact that questions about these signals seem to increase every time the solar cycle starts to pick up.

T!
 
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