Strange noise on MDZhB (UVB-76)

[Fred Barclay]

I need help! I've suddenly developed an unexplained interest in spending hours of time listening to shortwave radio. Specifically, I listen to 4625KHz (the infamous Buzzer) in hopes that someone will suddenly break out in Russian code words rather than the standard "foghorn".
A few hours ago, I thought it sounded awfully like someone was whistling, so I recorded 47 seconds of it (the sound stopped). I've uploaded it to Dropbox here.
The trouble is that I'm no ham expert. I didn't go to the School of the Air or anything, and I've never studied shortwaves before. With that said, I'm confused on what the sound might be. On one hand, it seems strange that the "whistle" kept pretty close time--which leads me to think it was just some strange interference. On the other hand, the noise sounded distinctly human. On the recording, you can hear where it sounds as if it were blowing on a mic, and some wavering that sounds like a person to me.

Anyway, please listen and let me know what you think! Could this just be some sort of interference?
(I was using http://websdr.ewi.utwente.nl:8901/ as I don't have a wireless myself.

[ofb]

I vote apophenia; you're seeing faces in the clouds. That's not a bad thing - pattern-matching is what we do.

FWIW I like this stuff. I like it raw, and arranged into music, and music from electronics.

Occassionally there's moments of brilliance on somafm's dronzone. But for easier 'quick fun' try mission control, which is similar but overlaid with tapes from from the apollo missions.
http://somafm.com/missioncontrol/
http://somafm.com/dronezone/

[Fred Barclay]

I've seriously thought about that. The only thing is that something was there--it's not as if I put it together. I just don't know what caused it.

Did you have a listen? You can hear the *normal* operation of the channel for the last 30 seconds. I also noticed that the pitch of the "whistle" went up towards the end (it was less than a half-step below a full octave above the buzz at first, resolving to a perfect octave the last two or three times).
I promise I'm not going off the deep end...

[ofb]

Ah. I see one way we're thinking about it different. You see the whistle as 'keeping time'. I just see it as interference/artifact that's able to come across in the sections between the pulses of the buzz.

I can see how your version would pretty much make you jump out of your skin in surprise.

[Fred Barclay]

See, that's what I need to hear. I know almost nothing about radios, or shortwaves, so having you actually call it "interference" is helpful.

[Try'n 2 Learn]

i gotta admit it Fred, you'd probably make a funny drinking buddy. the thing is with shortwave, it is notoriously susceptible to atmospheric conditions. whatever it was, it definitely sounds deliberate. certainly could be some sort of morse-code (or maybe other code) effort from whatever transmitter.

[robert-e]

A couple of decades ago, the US and Russia were experimenting (and using) "over the horizon" radar, operating in the high frequency bands; in particular around 14 Mhz. Lately, some middle east countries, and china have been using similar systems. If you load your audio file into audacity, you will see that it is definitly man-made noise. I would be willing to bet "pie and coffee" that what you see oth radar. For historical interest; search on "over the horizon" radar and woodpecker. The Russian system was frequency agile. If you wanted to make it shift frequency, you could transmit a continuous stream of morse code dots, that would disrupt it, and it would move off frequency. I imagine things are much more impervious to that now, as evidenced by the wave shape.

Regards,
Bob

[robert-e]

You can find samples of various over the air radar signals, as well as many others here:

http://www.sigidwiki.com/wiki/Category:HF

Bob