Optimal Points of Using Central Differences Method for GPS Velocity Determination

Three points central differences method(CDM) has been widely used in GPS velocity and acceleration determination.However,it will lead to a considerable error when the carrier has a strong maneuverability.We prove that the truncation errors will be decreased and observational errors will be increased when more points be used in CDM.For validation of our analysis,some airborne GPS data are used.The results show that if data interval is 1 Hz,average velocity and acceleration of carrier is 20 m·s-1,0.2 m·s-2 respectively,9 points CDM is the best.Comparing of common using 3 points CDM,the precision of velocity determination is improved about 40%.And the improved level is more significant when the carrier has a strong maneuverability.