What are those 4 tones on 75 meters?

[hamstang]

I regularly work 75 meter SSB and hear 4 quick tones about every 2 minutes. I heard the tones on 60 meters recently also. This may have been cussed and discussed for years, but I have never read anything about it. Anyone know what the tones are and where they originate? No wild guesses please, as I can do that on my own! BTW, I am in the SE US.

 

[WB4CS]

Can you post an audio or video clip of these tones? It's hard to know what you're hearing without hearing it ourselves.

 

[Darth_vader]

Polytone "number" station?

Those things do tend to show up in odd places on the shortwave spectrum from time to time.

 

[Token]

I regularly work 75 meter SSB and hear 4 quick tones about every 2 minutes. I heard the tones on 60 meters recently also. This may have been cussed and discussed for years, but I have never read anything about it. Anyone know what the tones are and where they originate? No wild guesses please, as I can do that on my own! BTW, I am in the SE US.

As WB4CS said, a recording is going to be needed or every answer you get will probably be a wild guess. There is just not enough detail in your description to do more than guess.

Since you describe it as “4 tones” I assume you are not talking about a chirpsonde? They hit every ham band periodically, but they do not make specific tones, rather they make a sweeping sound.

Videos of chirpsondes just to confirm this is not what you are hearing:
Sounder, Chirpsounder in ham 17M band, May 27, 2012, 1421 UTC - YouTube
Sounder, Chirpsounder in ham 20M band, May 27, 2012, 1456 UTC - YouTube

One other thing to exclude, a digisonde can sound like stepped signals under the right conditions, and also hits 75 and 60 pretty frequently. A video to help exclude it as a possibility:
Sounder, Digisonde "Grinder", October 05, 2012, 1501 UTC, 4700 kHz - YouTube

Polytone "number" station?

Those things do tend to show up in odd places on the shortwave spectrum from time to time.

These stations mostly avoid the ham bands, although that does not mean you will never hear them there. But more importantly from the OPs description it is something that happens frequently, and polytone stations normally hit a frequency for 2 to 5 minutes solid and then move on, possibly repeating the next day or even every day.

T!

 

[WB4CS]

Over on QRZ forums, there's a couple of posts that refer to single letter beacon stations (numbers stations) that have been spotted on 40 M CW. Apparently, they are sending a constant string of either "C" or "P" in CW. Both characters in Morse Code would be 4 "tones" long. C is -.-. and P is .--.

According to the wiki article that is posted over on that forum, those beacons show up on the 75 and 40 meter amateur bands. Maybe it's possible this is what you're hearing?

Letter beacon - Wikipedia, the free encyclopedia

Again, if you can provide a recording we can better answer your question.

 

[Token]

Over on QRZ forums, there's a couple of posts that refer to single letter beacon stations (numbers stations) that have been spotted on 40 M CW. Apparently, they are sending a constant string of either "C" or "P" in CW. Both characters in Morse Code would be 4 "tones" long. C is -.-. and P is .--.

According to the wiki article that is posted over on that forum, those beacons show up on the 75 and 40 meter amateur bands. Maybe it's possible this is what you're hearing?

Letter beacon - Wikipedia, the free encyclopedia

The letter beacons are on continuously. That is the letters are sent one after the other, there would not be a couple minutes between them. Also, when I live in the US south east (were the OP says he is) I could never hear the beacons in the 75 (the beacons are normally in the 3593 to 3595 kHz range) or 60 (beacons normally 5153 to 5155 kHz range) meter bands.

T!

 

[hamstang]

Thanks for the replies. Non accurately described what we have been hearing on 75 meters and other lower bands. I am working with a friend who has a Flex radio hoping he can provide a jpg of the wave pattern, or maybe a sound file.

 

[hamstang]

Audio File of Tones

Here is a small mp3 file of the tones I hear. May have to increase volume.

 

[Token]

It sounds something like the VIPIR sounder, but VIPIR normally has 8 pulses, not 4. A screen shot of the waterfall would help a bit, at least to narrow it down some more. My bet is it is going to be a sounder, just not sure which one.

T!

 

[k9rzz]

Those are "4 tones"??

Pretty weak in that recording. Have you ruled out a local stray source of RF as a possibility? Who say's it's got to be a deliberate communication?

 

[hamstang]

Those are "4 tones"??

Pretty weak in that recording. Have you ruled out a local stray source of RF as a possibility? Who say's it's got to be a deliberate communication?

Every 2 minutes, 24/7 Is that deliberate? It is heard by other hams within a 50 mile radius for certain, maybe much farther.

 

[k9rzz]

If it's 24/7 on 75 meters, then it's not propagating. Definitely local (within 50 miles).

 

[Token]

A screen shot of a 50 kHz wide spectrum display and waterfall would help to confirm what this is, but I feel pretty confident it is an ionosonde.

Exactly which ionosode is a bit up in the air, most probably it is either a lesser used waveform of the DPS-4 Digisonde or a lesser used waveform of the VIPIR network. My bet would be on the DPS-4 or DGS-256.

Hamstang, you are in Charlotte, correct? I believe UNC has a ionosonde node outside of Asheville, NC. This should be 100 miles or less from you, and a good bet as to the source if it is 24/7 (I can hear the Vandenburg digisonde almost 24/7 near 75 meters or a bit above, and they are a little further away from me, at about 165 miles). I know for sure there is digisonde on Wallops Island, but that is a several hundred miles and I would not expect 24/7 coverage near 75 meters. There also might be one near Charleston, but not sure about that one at all, I have heard it is there but found no documentation of it.

While I feel sure your recording is of a sounder I am a bit confused by the timeline. Normally these sounders are every 5 to 20 minutes, depending on which specific installation location it is. I have never seen one sound every 2 minutes, in fact it might not have time to complete a full cycle in 2 minutes (they all cycle in frequency, from one extreme to the other, often about 2 to 30 MHz, to test propagation over a wide range of frequencies). They are also generally coordinated, so that they do not interfere with each other. I suppose it is possible, if you are really hearing them every 2 minutes (has anyone really timed them at 2 minutes, or is that a guestimate?), that you are hearing more than one source. First one comes by and a couple minutes later another, and a couple minutes later yet another. But then one or more of them should be heard less frequently, as propagation kills the path. And also that would put you in just exactly the wrong spot. For example I never see the same kind of sounder that often.

Recording of both the same kind of pulses you report, and a “normal” VIPIR burst.
Sounder, possibly 2 kinds, 8611 kHz and 6960 kHz - YouTube

T!

 

[hamstang]

40 meter sound file

Here is a recording of the sounds we hear repeated every 2 minutes on several ham bands. The tones are loudest below 10 mHz.