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

Different powerline communications devices may have different signal and modulation characteristics, so this may still be powerline communications even if a sample of one such signal does not match this. But it could be something else as well. The wide bandwidth and rather "dirty" appearance suggest that it could be high speed powerline communications (ethernet over power line for example) and the fact that it does not affect ham bands might mean that the designers have added filtering to avoid interference to ham radio and possible complaints from amateur operators.

I can't really think of any other type of source for this, except perhaps a power electronics device with very poor interference suppression. But such a device would very likely output garbage on the ham band as well and not leave a sharp gap like that.

Jammer - not impossible but unlikely. Local jamming would be very unlikely and what would they jam? Military jamming from a faraway source? It would be noticeable elsewhere and I haven't seen any other people reporting this kind of signal. Large scale broadband jamming like this would also require very high power. Radar? The sharp tapping noise sounds like a radar but this "dirty" spectrum and using such a massive bandwidth does not make sense, and I haven't seen anyone reporting a new radar like this either. Emcbro (talk) 03:00, 6 September 2024 (NZST)

Agreed. I'm waiting on new equipment to arrive and a little free time. I will take readings from different points in the city that will clarify if it is local QRM. I'll report back my findings here. Mmcc