The signal looks like the Graves radar, as you suggested. Changing the bandwidth is as easy as clicking on the left, under filter.
You have the 3.2 kHz bandwidth selected (default under USB mode).
The almost vertical lines in some screenshots show a passing target at Mach 6 relative to your location and the Graves transmitter. Graves is a Passive radar in that it transmits a CW tone and by looking at the Doppler from various receiver locations, the target range is determined. To observe local targets, click the CW-U Mode and reduce the filter to 267 Hz for a +/- 500 meters per second,relative, Doppler target observation.
From your screen shot, it looks like the fluctuations in the carrier are nearby targets. Relative Velocity = Doppler frequency x 3e8 / (observed frequency * 2).
Once you calibrate the receiver ( -12 ppm off? ) you will have a better idea of the correct frequency, and Doppler! This SDR drifts a lot under temperature variations so be suspect of the absolute frequency even after calibration.