HFU HF Underground
Loggings => HF Mystery Signals => Topic started by: mmcc on September 23, 2024, 1923 UTC
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I see this signal, sometimes for several hundred KHz, sometime for over 1MHz, spanning anywhere from 2MHz-70MHz.
(https://i.imgur.com/BBTI96a.png)
1. 2MHz-70MHz (bandwidth of several hundred KHz to 1MHz)
2. Visible 24/7
3. Continous (Can sometimes switch on/off on certain frequencies)
4. Receiver Mode - N/A
5. UK
6. Looks like a multiplex signal. Has an unstable modulation of around 25Hz.
For reference, here is the audio:
https://www.sigidwiki.com/wiki/Unidentified_Signal_5 (https://www.sigidwiki.com/wiki/Unidentified_Signal_5)
Any ideas?
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Dumb question time: You're certain this isn't some sort of RFI?
Does the signal propagate? I didn't hear any obvious fading in the sound clip.
Personally, I haven't heard anything exactly like that signal. The closest noise to it is OTHR (over the horizon radar). The famous Russian Woodpecker of the 1970's and 80's had a similar sound and pulse rate, but it also moved around a lot, and most times you could hear fading of some sort.
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Sorry for the late reply. Lost my login details and emails are not being received for a password reset. I have been looking at this signal for a number of weeks. I'm fairly confident that it is not RFI at this stage. As far as I can tell, its an undisclosed OTH radar located somewhere along a line that passes through Alaska, Canada, Greenland and Ireland.
The below image shows that each channel is independently modulated:
https://imgur.com/urRTaYE
I caught the signal changing modes, from an unstable 40ms pulse, on each channel to a more stochastic pulsed output. Then I caught each of the channels sweeping the frequencies.
https://imgur.com/iUOgV6e
The only two known OTH radars are Nostradamus in France and the Polar OTH in Canada. But this seems to be something new.
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This is caused by powerline ethernet. I've had the same happen and it went when the powerline system was replaced for another one.