ELT and other types of those beacons can transmit test frame or alert frame. Test is running when I push test button.
Protocol is the same, but initial bits indicate that frame is “test” or “alert”. This decoder I attached link will show what type of trasmition it is.
I have recorded some “wav” files with both signals, I can share them. They are properly decoded by attached software (http://jgsenlis.free.fr/).
I obtain all signals by using original emergency beacon but with dummy load instead antena (to prevent signal getting to satellite) and by handheld 406MHz Yaesu receiver. I recorded it just by audio program on my Mac.
I can also get dumps by Flipper but I’m not sure how to setup “RAW” to get it correctly. Modulation is Narrow FM (so standard, mono FM).
IEEE_AESM_Mladenov2021 (2).pdf (1.4 MB)