Hi ,
just to comment that some radars provide, for each target detected, the Doppler velocity as a raw measurement made directly by the device. So it would be important to differentiate “range_rate” which, as JWhitleyAStuff said, the polar longitudinal velocity of tracks, from the “doppler_velocity” , which is also a polar longitudinal velocity, but issued from a wave signal processing step, and not issued from an object tracking process.
From the robotics perspective, doppler velocity is a raw measurement, like range.
best,
andreu