Well, once the question is answered it’s interesting to discuss technicalities.
Satellite compasses for marine navigation do something like this.
With an array of spatially separate GPS receivers, it becomes possible to identify speed with high accuracy, as well as orientation and rate-of-change of orientation, even when stopped. Knowing your ship’s geometry - length, width, and fore/aft/lateral installation position of GPS compass - it can calculate speed and direction of movement for the various parts of the ship.
Not that much experience.
Had to do a deep dive into GPS for possible uses. Ongoing usual level after that. Forgot a lot now. As to update rate. I left the factory default. I believe it was 1 Hz. At 9600 baud. Over VHF radio. Not sure what the usable top rate might be. The Ucenter plotting showed great stability from stationary to 30 KPH. Ublox sells a nice kit for RTK experimenting/use. Base and rover with built in low power radios. Very compact units. Wondering if I can use it for my budding drone hobby.