To me this sounds like an OTH or over the horizon radar signal. Source of the transmission is unknown. Signal lasted approximately four minutes before stopping. The signal re-appeared a few minutes later again and was shifted slightly higher in frequency. This was on 17.154Mhz in USB mode.

This signal has a similar sound to the “mystery” signal I’ve been posting about during the past several months. This signal is fixed on 13.604Mhz. Anyone have any idea what this may be?

Came across this weak voice transmission followed by a data stream of some type. Signal was weak but clearly had an “echo” type effect. Following the voice was a data stream of some type. Almost like a HM01 transmission. Not certain about the origin of this signal.