Many thanks to SWLing Post contributor Carlos Latuff, who writes:
Dear Thomas, I was doing my morning radio listening on the Guaíba waterfront in Porto Alegre, Brazil, when I came across this Morse code signal at 8207 kHz by pure chance. I tried to decode it using apps but didn’t get good results. As I’m not good at CW, I’m leaving the audio here so that your qualified and attentive audience can, perhaps, discover what this transmission is about. Thank you very much for your attention.
Update from Carlos:
I contacted Ary Boender, a Dutch shortwave listener and specialist in HF utility radio communications. He said:
“The recording starts with HR SVC GA NA25/XE56/ 0. You heard a Chinese military station. “HR SVC GA” is typical for the Chinese military”.
Mystery solved!