Yep, what Token said, P4 mode. It sounds like hfdl because both employ psk modulation for the data bits, and I supose that like the doppler tone in hfdl, P4 uses the sweeping tones for doppler equalisation. No inexpensive decoders for P4 that I know of, but looking at udxf logs might point to a likely source.
Also, you tuned a bit off by a few hundred Hertz, when trying to id a sig, allow some slack from each side of a given sig so you get all of it inside the filter passband. That way we have all of it to work with rather than just 5/8s.