Hard to say with certainty, but it looks like a burst from an OTH radar. The ROTHR radar system is a likely candidate as it transmits FMCW bursts like that.
Definitely an OTHR. The appearance depends on the SDR setting and you cannot rule out the USN ROTHR because of that. (I have monitor the ROTHR in VA from "across the street". If he changes the bandwidth or catches audio (yes tricky, but they often cycle back to repeat a frequency a couple minutes later), I might be certain as I know well the parameters of the system.. If not the USN ROTHR, this looks like it could be the Australian JORN as an alternative. Strongly suggest you see more detailed OTHR radar info (I am the author) at
http://udxf.nl/HF-radars.pdf