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eHam Forums => SWL (Shortwave Listening) => Topic started by: KC6RWI on March 18, 2019, 09:58:01 AM



Title: Shortwave sounds I've always heard.
Post by: KC6RWI on March 18, 2019, 09:58:01 AM
Sadly I don't have a sample of what I am hearing, I'm sure others who have monitored 28 mhz and lower have heard this sound. Years ago I was told it was a diaphermy machine. I checked utube under odd shortwave sounds and I found some interesting and also dumb submissions. The sound I hear is a circular sound that starts low in frequency and rises up. I always imagine an a visual picture of an upside down hurricane, it also sounds similiar to the last bit of water going down a drain.  Maybe if someone has a good utube that might id this, I tried that first


Title: RE: Shortwave sounds I've always heard.
Post by: NO2A on March 18, 2019, 12:12:41 PM
For quite awhile I've heard something I can't explain on AM broadcast. It sounds like someone in a tunnel saying "Ahhhhhh" with kind of an echo to it. Can't remember the exact frequency, but I want to say around 650 KHZ. I've heard it on more than one radio, and more than one location. Maybe some kind of heterodyne? I only hear it once in awhile.     ???


Title: RE: Shortwave sounds I've always heard.
Post by: KX4QP on March 18, 2019, 02:58:42 PM
Diathermy was an old therapy which involved heating tissues with RF (as I recall it was in the VHF range, which penetrates better than microwaves).  The emission was generally unmodulated, so it should sound like a solid key-down CW tranmitter, only on above 10m band.  The devices didn't have anything you or I would call an antenna (most had a sort of can shaped device on a cable where most of the RF radiated), and I'd be very surprised if you could hear one more than a mile or so from the clinic that had it.

Also, AFAIK, they've been out of service for decades, since less hazardous methods of heating tissues came into favor (there's no high voltage in a heating pad, never mind a salts bath).


Title: RE: Shortwave sounds I've always heard.
Post by: KAPT4560 on March 18, 2019, 03:20:19 PM
 Medical diathermy and violet-ray machines were noises sometimes heard in residential settings. The more affluent patients could afford having them at home.

 The cyclic noises, like a squeaky wheel are probably older fax (facsimile) machines. I remember hearing them in the evenings above the AM broadcast band.

 The internet has taken away a lot of services that were previously done by radio.


Title: RE: Shortwave sounds I've always heard.
Post by: RENTON481 on March 19, 2019, 10:22:44 AM
If it's a squish sound it could be Jupiter.

I used to hear Jupiter a lot when monitoring 12 meters, 11 meters sideband, and monitoring 10 meters.

Jupiter puts out radio waves, and when you hear it on SSB it sounds like a second long squish noise.


Title: RE: Shortwave sounds I've always heard.
Post by: KC6RWI on March 21, 2019, 12:58:42 PM
The diathermy idea was something I heard years ago and they still make them, in fact when I looked last week 3 freqs where mentioned, one being 27.12 mhz. I've searched the utubes for sounds and nothing matches, I think I am probably hearing some sort of radar signal. The utubes of radar and usually continuous cycles of sound, The sound I hear appears to random to me and just one quick cycle. I'll try to get a recording.


Title: RE: Shortwave sounds I've always heard.
Post by: KC6RWI on March 21, 2019, 04:11:35 PM
Found it, its posted on this link, the signal I hear starts low and goes high in sound, this is backwards but it possibly the same thing, Still no mention of what it could be, and I only hear once signal in long time.
https://www.youtube.com/watch?v=zFvDA5_msnM


Title: RE: Shortwave sounds I've always heard.
Post by: NO2A on March 22, 2019, 08:20:07 PM


If it's a squish sound it could be Jupiter.

I used to hear Jupiter a lot when monitoring 12 meters, 11 meters sideband, and monitoring 10 meters.

Jupiter puts out radio waves, and when you hear it on SSB it sounds like a second long squish noise.
I've heard that too while operating on the bands. Never knew that could be Jupiter. Curious what that would sound like on AM. I've never heard it below the amateur bands.


Title: RE: Shortwave sounds I've always heard.
Post by: RENTON481 on March 25, 2019, 05:38:17 PM
Found it, its posted on this link, the signal I hear starts low and goes high in sound, this is backwards but it possibly the same thing, Still no mention of what it could be, and I only hear once signal in long time.
https://www.youtube.com/watch?v=zFvDA5_msnM

That sounds like Jupiter.


Title: RE: Shortwave sounds I've always heard.
Post by: KC6RWI on March 26, 2019, 01:14:03 PM
Yeah, thats the bands I would be monitoring. I am going to search it out and put it to rest. That sample very close, but when I hear it, its once and random. I used to think the band was changing when I heard, but maybe that was just coincidence.


Title: RE: Shortwave sounds I've always heard.
Post by: KE5HVM on March 28, 2019, 10:04:46 AM
Super interesting!
I love RF-sleuthing.

Regarding Jupiter, it will depend on whether Jupiter was above the horizon at the time of your observations.

Here is a great link to listening in to Jupiter:
https://radiojove.gsfc.nasa.gov/

Gerrit
KE5HVM


Title: RE: Shortwave sounds I've always heard.
Post by: KC6RWI on March 29, 2019, 12:30:59 PM
Its interesting, something somewhere is out there is making that signal, its been there for decades, I always thought it was an indication of propagation. Its not wave like sounds like from the link you posted.
Years ago when everything was analog, I had my scanner on in metro Los Angeles, there was so much to pick up on vhf. I got a signal close by me on 168mhz. It was audio from body mic, I put on my jacket and hid my scanner and followed the signal, it came from a store front income tax office. Walking back and forth I covertly took off my antenna and it still was there. There was nothing for me to do but head back to work.   


Title: RE: Shortwave sounds I've always heard.
Post by: NO2A on March 29, 2019, 04:09:11 PM
Does our own Sun send any audible sounds?


Title: RE: Shortwave sounds I've always heard.
Post by: KAPT4560 on March 30, 2019, 03:23:23 AM
 Outer space is rife with noise across the entire electromagnetic spectrum. Just like having a bad neighbor  ;D:

 https://www.jpl.nasa.gov/multimedia/sounds2/index-nasa.html

 https://space-audio.org


Title: RE: Shortwave sounds I've always heard.
Post by: SM0AOM on April 05, 2019, 06:36:00 AM
Diathermy was an old therapy which involved heating tissues with RF (as I recall it was in the VHF range, which penetrates better than microwaves).  The emission was generally unmodulated, so it should sound like a solid key-down CW tranmitter, only on above 10m band.  The devices didn't have anything you or I would call an antenna (most had a sort of can shaped device on a cable where most of the RF radiated), and I'd be very surprised if you could hear one more than a mile or so from the clinic that had it.

Also, AFAIK, they've been out of service for decades, since less hazardous methods of heating tissues came into favor (there's no high voltage in a heating pad, never mind a salts bath).

Having a brief medical electronics background, I can give some more background.

"Diathermy" is a broad term, and there are a lot of different applications in different medical disciplines.

First, we have surgical diathermy, where RF is used to cut through tissue, stop bleeding by "welding" blood vessels shut and coagulate blood at the same time. This usually operates in the "few" MHz range and with power ranges around 10 - 200 W. Some internal surgeons use this method a lot.

Second, the "general heating" application where muscles and joints are heated through dielectric heating using RF generators usually around 27 MHz and in the "several hundred watt" power range.
This is intended to counter inflammatory diseases and reduce pain by increasing the blood flow in the tissues. It has fallen somewhat out of use due to improved medication, but may still be encountered.

Then we have the "localised heating", where UHF or microwave energy is used to heat small sections of the body locally. 433 and 2450 MHz were the frequency bands I heard about in the 70s.

This technique seems to have been largely abandoned due to safety concerns, I remember my lecturer mentioning the risk of blinding patients due to overheating of the retina and optical nerve when trying to treat ear and nose infections (sinusitis).

Another application was heat treatment of urinary bladder cancer using small antennas on 2450 or 5600 MHz that was placed directly onto the tumors. This was the subject of an MSEE Thesis written by one of my friends at University.




Title: RE: Shortwave sounds I've always heard.
Post by: KC6RWI on April 05, 2019, 03:53:10 PM
thanks for that, your post above indicates the amount of technical people tuned into this site.


Title: RE: Shortwave sounds I've always heard.
Post by: SM0AOM on April 06, 2019, 01:52:53 AM
Returning to the original question, since you have heard this for a very long time, it probably is a more or less legitimate communications mode of some form.

If it would have surfaced during the last 10 - 15 years or so, spurious emissions from switching power supplies, TV/computer screens or data communications gear would have been the "prime suspects".

Some of these can generate very strange sounding effects.


Title: RE: Shortwave sounds I've always heard.
Post by: KC6RWI on April 06, 2019, 11:10:52 AM
I am going to check the net once in awhile and see if i can find any mention of the sounds. I'll just keep my ears and eyes open. maybe I'll search 10 and 11 ssb meter sounds.


Title: RE: Shortwave sounds I've always heard.
Post by: WB0DZX on April 09, 2019, 11:34:02 AM
Without hearing the signal, I'm only guessing. It may be one or more ground-based swept-frequency ionospheric sounders, i.e. ionosondes. Those are best heard with BFO modes (not AM or FM). It sounds like a swisher, best descibed as someone key down while quickly turning the VFO from a low frequency to a higher one sweeping through the frequency you are tuned to. That is what is automatically happening, synchronized to associated receivers doing the analysis.
 
They are used mainly for real time propagation analysis.
 
I couldn't find an easier link than this one. "Fast forward" to 28:15 (min:sec) i.e. -18:30 remaining.
https://www.magic.co.nz/home/archivedtalk/audio/2017/12/strange-shortwave-noises.html
 
A closed circuit version on assigned fixed frequencies throughout the HF spectrum is ALE: Automatic Link Establishment. However, it keeps track of the best path between each station in a network - not what ionospheric conditions exist. That is discussed earlier in the above audio.
 
Mike WB0DZX


Title: RE: Shortwave sounds I've always heard.
Post by: WB0DZX on April 09, 2019, 11:41:42 AM
Also check out CODAR. Also earlier in the link. However CODAR is regular and periodic on certain fixed frequencies. It is a watery sound. BTW since the sound you describe is somewhat wideband, it would Not be a chirp (pulse) sounder.
 
Mike WB0DZX


Title: RE: Shortwave sounds I've always heard.
Post by: K5TED on April 09, 2019, 10:19:56 PM
Whistlers are remarkable bursts generated by
lightning discharge. When part of the discharge
energy escapes the ionospheric barrier and propagates through the magnetosphere, whistlers can
be heard in radio receivers as a relative long
whistle decreasing in frequency, from about 6
kHz to a few hundred Hz (fig. 6). In the magnetosphere whistlers interact with free electrons
and are forced to propagate along the Earth’s
magnetic field lines. The harmonic components
of the signals identified as whistlers correspond
to electromagnetic waves that have traveled several Earth radii arriving at different times to the
observer. Lower frequencies are delayed 3-6 s
with respect to the higher ones. The dispersion of
a whistler depends on the length of the path over
which the signal travels as well as the characteristics of the propagation medium such as its electron density

https://www.earth-prints.org/bitstream/2122/3674/1/11bianchi.pdf


Title: RE: Shortwave sounds I've always heard.
Post by: WB0DZX on April 09, 2019, 10:23:09 PM
Hi, K5TED. You may be referring to the swept frequency "signal" from lightning known as whistlers. I studied those for Project INSPIRE, a NASA-citizen scientist collaboration.
 
If so, their domain drops off sharply to nothing above 20 KHz (radio). Above that, including the area around 28 KHz, the sferics are run of the mill crashes that sound the same no matter what the frequency. They don't move and sound the same no matter the receive mode.
 
Mike WB0DZX


Title: RE: Shortwave sounds I've always heard.
Post by: WB0DZX on April 09, 2019, 10:31:43 PM
Nobody is sure of the mechanism or how often it may occur, but my reception included what the national leader said was the only "reverse whistler." It went from high to low frequency in its sweep. No other such whistlers from that time slot.
 
I'm left-handed so that doesn't totally surprise me.
 
Mike WB0DZX


Title: RE: Shortwave sounds I've always heard.
Post by: WB0DZX on April 09, 2019, 10:34:39 PM
Oops: next to last message show read 28 *** MHz ***!


Title: RE: Shortwave sounds I've always heard.
Post by: KC6RWI on April 10, 2019, 01:50:19 PM
Thanks for all the interest, I spent sometime this morning checking some utubes. The closest thing I heard is over the horizon radar. There is just one problem with that. I just get one cycle and its random but who knows. I seem to get just parked on 10 or 11 meters, just one funny burst. Maybe its a test signal to check the equipment, Thanks again, Leonard