Without a sound file it is not possible to confirm, but this is almost certainly HFDL, High Frequency Data Link. This is a known frequency for HFDL and the image looks like it is probably HFDL. A more detailed closeup image of the signal on the waterfall could help a little also.
HFDL is HF based ACARS, it is a data link used in aviation, including aircraft in flgiht.
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