Method and Analysis of Acceleration Determination Using Stand-Alone GPS Receiver for Airborne Scalar Gravimetry

Kinematic acceleration estimated by GPS (Global Positioning System) is significant for airborne scalar gravimetry. Comparing with the conventional approach of DGPS (differential Global Positioning System), we introduce an alternative approach of the standalone receiver, which is using time difference carrier phase observation between two successive epochs without the requirement of ground-base stations. In this approach, time series of high-precision epoch-wise displacements are estimated firstly, then a Taylor approximation differentiator with the consideration of actual gravity data is applied to obtain accelerations as well as velocities. Meanwhile, the effects of satellite orbits and clocks errors on acceleration estimation are analyzed carefully. The results show that the satellite clock products have significant impact on the acceleration determination, while it can be neglected for orbits errors. Then the performance of the proposed approach is validated using a flight test carried out in Shaanxi Province, China. Aircraft accelerations are determined using the proposed method, then are used to calculate the gravity disturbances. According to the comparison, the derived gravity disturbances show a very good consistency with those obtained from DGPS, and the difference is better than 1.0 mGal at the filtering period of 100 s. Furthermore, the recovered gravity disturbances along the survey lines are checked for internal consistency at the intersections, the RMS is 1.13 mGal consistently at the filtering period of 100 s. Finally, comparing with the measured ground gravity, the accuracy of the proposed method is basically consistent with the DGPS methods', which indicates that it is feasible for airborne scalar gravimetry without ground base stations.