Many thanks to SWLing Post contributor, Carlos Latuff, who writes:
Attached are two different recordings.
Both made in South Brazil.– Florianópolis, 26/11/2019, 19h13 (Brasilia time) 12015 kHz
– Porto Alegre, 12/12/2019, 20h11 (Brasilia time) 7455 kHz
Searching on the Web I found these two frequencies related to US Navy NATO RTTY station STANAG 4481:
- https://www.sigidwiki.com/wiki/STANAG_4481
- http://mt-milcom.blogspot.com/2018/12/us-navy-stanag-4481-encrypted-fsk.html?m=1
Are you able to confirm this?
Thanks for your inquiry, Carlos! Unfortunately, I cannot confirm this. If your radio had been in SSB mode, it would have made the RTTY pop out and we could have perhaps confirmed at least the RTTY mode with FLDIGI. I’m hoping a savvy SWLing Post reader can help you ID these transmissions. Please comment!
Both of them sound like PSK but listened to in AM mode with some local interference that occasionally makes tones 🙂
Both would sound more “sensible” in USB
Next time you hear them, pop over to websdr.org and see if you can find a local SDR and listen to it on USB, so you know what it sounds like 🙂
Thank you Neil, I have plans, in the soon future, to purchase a SSB capable radio set.
Thomas, once again, thank you for posting my request. Merry Xmas and Happy New Year.
Listened to both, really don’t have a clue. I agree with Thomas, next time use your BFO or SSB switch so we can hear tones. The first one, if I had to hazard a guess might be a weak RTTY station. When listening to digital modes like RTTY, FAX, ALE, SITOR, etc., always have your rcvr in SSB mode.
Thank you, Mario, but my radio set has no SSB filter. It’s a Tecsun PL-606.
Yes it might be a NATO broadcast, per the list in this thread….
https://forums.radioreference.com/threads/undecodeable-signals.381373/
I have to find some time to put this in our wiki – it comes up so often that it really should be there
Much appreciated, Mike.