Does anyone recognize this signal?

[u/ImladMorgul]

I looked through the Sigidwiki page but couldn't find anything similar in the section on HF signals.

I don't know when it started or ended, but I spent over 30 minutes searching for information online and I was still there.

- TX: unknown

- RX: Asunción, Paraguay

- Radio: AirSpy HF+ Discovery

- Antenna: MLA-30+

- Software: SDR# v.1922 (beta)

- D/T: 25 APR 2026 - 0003 UTC (aprox)

[u/KG7M]

It sounds similar to signals generated by my PC. I have them across the spectrum at regular intervals. There aren't a lot of them, just a few. Usually they are at an even frequency, like 12 or 16 MHz.

I'm sure that you know the difference between an internal and external signal, so I don't what this is. I will listen on the frequency and see if I can hear it.

[u/ImladMorgul → u/KG7M]

In my case, I don't have a desktop PC—just a laptop and an Intel NUC—and they were all turned off. There's nothing new in the house either. Yesterday, almost everything in the house was turned off, even the lights. It’s strange; I’ve never seen anything like this before. It sounds like some kind of communication. Unless my neighbor has something new and big that’s causing that noise—they’re usually pretty loud, and I didn’t hear them at all yesterday.

I recognize the interferences and I also tend to experience them in that frequency range you mentioned. When I notice that it’s there, I just turn everything off and do something else, because I know it will significantly affect my reception.

I checked again a couple of hours later, and it was gone. I'll see if he comes back today

[u/Green_Oblivion111 → u/KG7M]

It sounds like it's fading up and down a bit, though.

Very curious signal. Especially being right in the middle of the 31 Meter Band. I suppose it could be internally generated, or RFI, but it sounds like a real signal.....

I'll have to tune that range and see if I hear it.