HFU HF Underground
Loggings => HF Mystery Signals => Topic started by: WA4FHY on October 14, 2017, 0246 UTC
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I have noticed this signal for at least 6 months. I am guessing that it is some sort of sounding transmission. The signal seems to be on 24 hours / day and I don’t see much change in signal strength. It’s kind of pleasant to listen to; reminds me of musical rain drops plinking down.
There is a period, end of one cycle to end of the next cycle, of ~4 minutes, 3 seconds. As the end of a cycle approaches, the “plinks” get stronger, shorter, and occur at an increasing rate.
I don’t think it’s a local signal and surely someone else has heard / seen it but I didn’t find anything similar when I skimmed other postings in this section. I am going to post a screenshot here that was made 11oct17 at 181105 UTC and then I will reply to myself and post an mp3 recording made on 12oct17 at 150335 UTC on; this is the last 15 seconds or so of a cycle.
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Here is the mp3 file...
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Lol that's some seriously wideband mfsk there.
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Did you ever find out anymore about this transmission? Just listening to the audio, it sounds similar to ROS mode used by hams (and some CBers etc.). This was developed 10+ years ago (?) and is now quite obscure in the ham world. Though, can't be normal ROS if the transmission is constant (ham ROS transmission would be more like 1 or 2 minutes long) and it would never be anything like 1.8MHz bandwidth! Also, nearest ham ROS frequency is 10130KHz. Certainly sounds similar though - like ROS but over greater bandwidth. I believe ROS mode uses a combination of several commercial techniques to allow simultaneous transmissions over spread spectrum. I have seen/heard "ROS type" transmissions similar to yours over which seem to exceed the standard 2250Hz bandwidth that hams use.
More info on ROS here: https://www.sigidwiki.com/wiki/ROS
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The Russians run some crazy wideband mfsk nets at times.