Talk:Unidentified Signal 5

Sounds very much like a radar, but bandwidth of more than 10 MHzMegaHertz (MHz) 10^6 Hz on HFHigh Frequency (3-30 MHz) doesn't quite make sense with modern OTHOver The Horizon (very long range) radars. Could also be interference from power electronics, powerline communications or something else. Has this appeared recently? Emcbro (talk) 05:45, 20 August 2024 (NZST)

Added a screenshot which should clarify that the signal is not electrical noise. Each of the channels (ranging between 1.5-5KHz) have independent modulation rate of around 40ms (25Hz), but the modulation phase seems to alter by about 150 microseconds. Its clearly a multiplexed signal of unknown origin. I would tend to agree that it is probably not an OTHOver The Horizon (very long range) radar, which means it is some form of comms. Mmcc

I'm inclined to believe that this might be interference from powerline communications, probably ethernet over power line adapters or something similar. The wide screenshot shows that it doesn't affect the 12m ham band, and I think some of these adapters may have been designed to not emit anything on amateur radio frequencies. Hard to say, really. Powerline communications have been criticized by amateur radio operators a lot and sometimes such products have faced scrutiny from authorities for excessive emissions. Emcbro (talk) 08:51, 25 August 2024 (NZST)

That was actually my first thought. I checked the entry out for Ethernet over Powerline before I posted. The modulation is different. I've added a side-by-side comparison of the audio to the page. It shows clearly that it is not Ethernet over Powerline. Mmcc