Som redan nämnts så är vanliga kommersiella GPS mycket exakta vid jämn fart, normalt uppdateringsfrekvens är 1 ggr/s så med häftig acceleration så blir det lite eftersläpp då den inte hinner med riktigt
Lite fakta från Garmin
Citat:
GPS receivers typically calculate velocity by measuring the frequency shift (Doppler shift) of the GPS D-band carrier(s). Velocity accuracy can be scenario dependent, (multipath, obstructed sky view from the dash of a car, mountains, city canyons, bad DOP) but 0.2 m/sec per axis (95%) is achievable for PPS and SPS velocity accuracy is the same as PPS when SA is off.
Velocity measured by a GPS is inherently 3 dimension, but consumer GPS receivers only report 2D (horizontal) speed on their readout. Garmin's specifications quote 0.1mph accuracy but due to signal degredation problems noted above, perhaps 0.5mph accuracy in typical automobile applications would be what you can count on.
Jag vill minnas att det angavs en avvikelse ca 0,05 m/s steady state för min Garmin GPS 60XS vilket omräknat till km/h blir ruskigt lite
