What is HF Comm Mode and How Does it Work?

[oneamp]

Strange, and unique, at least to me. What is this mode? A slow data mode I guess. I've never heard it before. Anyone know what it is? Listen for the tones below the noise..

{ URL removed by Mentor per OP's request }

 

[Bobbywhy]

It may be underwater (ocean) sound (ambient noise) with those tones being generated for some command/control function. What is the source of the file?

 

[Ryoko]

Don't know if this is the proper name for it, but I'm guessing it's single-tone multi-frequency encoding.

 

[oneamp]

I also assumed FSK but the very slow rate means that it has some application, such as mentioned by Bobbywhy. Very slow, long tones. The source of the file is a cheap Grundig yahtboy at about 14100 kHz. Bobby what do you mean by command/control function, and ambient noise?

 

[Bobbywhy]

Strange, and unique, at least to me. What is this mode? A slow data mode I guess. I've never heard it before. Anyone know what it is? Listen for the tones below the noise..

http://173.255.204.37/clip.mp3

oneamp, you did not mention in your first post (above) that the sound file was taken from your Short Wave radio receiver. So, I took a guess based on my work experiences in underwater acoustics.

Ambient acoustic noise in the ocean can be measured by simply putting a microphone (hydrophone) into the water and listening. There are many sources that contribute to this, including wind, rain, shipping, wave breaking, submarine machinery and screws, torpedoes, and many biologic species.

When one wants to send a command to an autonomous underwater vehicle to control it, a tone may be transmitted. It may well sound similar to your sound clip.

But all the above is a waste of time because I only guessed at the source of your sound file.
Now that you've explained the source is your short wave radio at around “14100 kHz†(should be “14100 KHzâ€) it is clear that you have recorded the ambient radio frequency (RF) noise present at your receiver’s antenna at the frequency your radio is tuned to. One can speculate on the source(s) of this ambient noise; aurora borealis “whistlers†contribute. http://www-pw.physics.uiowa.edu/mcgreevy/

The audio tones I cannot explain.

 

[sophiecentaur]

Since when has Kilo used upper case k?

 

[Bobbywhy]

Since when has Kilo used upper case k?

OOPs! Sorry, my mistake! The proper metric prefix for 1,000 is lower case k.

Thank you, sophiecentaur, for your vigilance!

 

[oneamp]

I disagree with what you have to say. I agree that it is not underwater communication, based on the frequency. I believe that waves ~14 MHz are attenuated, and that underwater comm uses low frequencies, like VLF. True?

I don't know if you can hear the tones well under the noise. It helps if you turn up the radio. But they are of uniform duration and occur in clusters, and are a set of maybe 3 frequencies, and are certainly modulation. They are not natural. Also the page you linked to talks about (well known) noise found on VLF/ELF. Mine is in HF, and HF to my knowledge isn't associated with things like whistlers. Regardless, the tones are nothing like any kind of natural noise.

 

[davenn]

interesting tones

too rthymic and repeative to be natural its almost very musical sounding.
Did you monitor this on AM or SSB ? Did you try changing modes ?
is it still there ?
where in the world are you ?

OK ... its wonderful what google throws up and refreshed my tired brain

I thought 14.1MHz sounded familiar, its right in the middle of the 20 metre ham band and 14.099 to 14.101 MHz is the beacon allocation.
so probably a 99% chance its an amateur beacon of some sort ( obviously not CW)

Dave

 

[oneamp]

Midwest USA, SSB. I did not change modes, good idea. I can check again tonight and see if it comes back, but it came and went, came and went, last night. Aren't beacons constant? I wondered if it were a beacon too but dismissed it since it wasn't CW. Interesting to learn that it's in the beacon range, thank you!

So strange that it is so slow..

 

[TurtleMeister]

You should be able to find samples of most all of the ham radio digital modes on youtube. I haven't listened to the link but from your description of it being slow and musical my first guess would be one of the JT modes. Here's a sample:



JT9 can sometimes be heard on 14.078 mhz.

 

[davenn]

yes beacons are constant ( constant frequency), BUT propagation isn't !

there is a world wide set of amateur beacons that actually change their power levels in steps
eg 100W, 10W, 1W cycling those levels over and over, this is to aid in working out propagation distance/conditions for a given freq and power level

Varying propagation conditions will have a major effect on any transmission over a period of time
(short - minutes, to long - hours)


Dave

 

[davenn]

You should be able to find samples of most all of the ham radio digital modes on youtube. I haven't listened to the link but from your description of it being slow and musical my first guess would be one of the JT modes. Here's a sample:



JT9 can sometimes be heard on 14.078 MHz.

That is pretty much the same, tho there seems to be multiple simultaneous tones, maybe we are hearing several transmissions superimposed ?

but the rhythmic sounds is virtually identical to those in the OP, distinct individual notes .
I don't play with JT65 etc, so not really familiar with how it sounds, now I am thanks

Dave

 

[TurtleMeister]

That is pretty much the same, tho there seems to be multiple simultaneous tones, maybe we are hearing several transmissions superimposed ?
Dave

Yes, sounds like two of them in there together. That's no problem for the software. I've never used the JT modes either but I have used WSPR. You can download the software at Joe Taylor's web site:

http://www.physics.princeton.edu/pulsar/K1JT/index.html

 

[davenn]

What's your callsign

Im VK2TDN main interests 50 MHz and up, particularly the microwave bands,
must be at least 2 yrs since my last HF QSO haha

Dave

 

[TurtleMeister]

What's your callsign

Im VK2TDN main interests 50 MHz and up, particularly the microwave bands,
must be at least 2 yrs since my last HF QSO haha

Dave

My main interest is cw and digital on HF. I have not been active for a few years because I'm currently living in an apartment. HF doesn't work very well with indoor antennas and s9 noise levels. Check your inbox for callsign.

 

[davenn]

yeah I have been in that apartment situation, it sux, I was pleased to get into a standalone home ( still renting tho )

my microwave sctivities all require me to do hilltopping anyway. whick I haven't done much of over the last couple of years due to health hassles

oneamp, looking forward to further reports from you :)
are you also a licenced amateur ?

cheers
Dave

 

[oneamp]

I'm in an apartment now and I was able to find that with a longwire indoors. Yes, I went through the modes online and listened, but there are so many it's hard to find the more obscure modes without a hint. I think what you linked in the video is close, and I guess it's probably a beacon! Thank you.

 

[davenn]

hey oneamp

The JT 9, 65 etc mode that turtlemeister commented on sounds like the one you have heard
As I commented earlier, I am not on HF much these days
It may not be a beacon, I don't know if there are digital beacons ? It may just be some hams doing the digital mode thing

I did ask, are you a licenced amateur also ?

Dave

 

[oneamp]

Yes I'm licensed but I never use it. Thank you for the information.

 

[Baluncore]

That sounds much like a data mode called “Piccolo”. Piccolo was widely used on HF for diplomatic links back in the 1970's. The bit rate in your recording is about 25% of the original data rate. IIRC the number of different notes used by Piccolo systems was either 16 or 32 depending on the version, which transferred 4 or 5 bits per tone. How many notes show up in the new beacon ?
http://en.wikipedia.org/wiki/Multiple_frequency-shift_keying

 

[sophiecentaur]

Alan Turing RIP ?
Go and sort it out chaps. If you can.
Think of it as a Christmas puzzle.
I'll bet it's a lot easier than Enigma.

 

[oneamp]

Thanks Baluncore.