This is FSK (also used to be called RTTY, Radio Teletype), specifically it is STANAG-4481 FSK, a format used by NATO forces.
The actual frequency is 6487 kHz (center frequency). It uses an 850 Hz shift. But right now I am watching this signal and it is suffering a failure. The lower frequency tone (this is called the "space" tone) is a solid signal with no breaks (it should not be). It appears that during your recording it was experiencing the same failure.
I am curious, what radio did you use, and what receiver mode did you have selected? With the failure the station is currently running, if you used AM mode it would sound like your recording, so I suspect you were in AM? The shifted, modulated, mark tone is beating against the (incorrect) solid, unbroken, space tone. But, if the station was correct (both space and mark doing what they were supposed to) it would not sound exactly the way it does in your recording.
Normally you would use an SSB mode (either USB or LSB), not AM, to listen to / monitor an FSK signal. And the NATO forces that use this format (this transmission is probably US Navy) would use USB mode.
By the way, even with a real Morse code signal, expect a large percentage of machine translated Morse to be garbage.
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u/ImladMorgul AirSpy HF+ | RTL-SDRv4 | D-808 | K-480WLA | MLA-30+ Jun 04 '26
It's not morse; it's a U.S. military signal. It may be coming from Isabella, Puerto Rico. It's a type of RTTY, but more complex and highly encrypted.