Accuracy of GPS-Derived Acceleration from Moving Platform Tests

Abstract

During the last few years major advances in kinematic methods of gravimetry have been made and recent tests indicate that results at an accuracy level of a few mGal are possible. In order to derive gravity from the output of an airborne gravimeter, precise position, velocity and acceleration of the gravimeter platform are required from additional sensors. The major problem is to separate inertial and gravitational acceleration. To assess the capability of GPS phase and phase rate measurements for the determination of precise acceleration in a dynamic environment, tests on a moving platform have been made. The platform motion is precisely controlled, i.e. independent control values for position and acceleration are available at all times. The paper briefly describes the test design and then focuses on investigating the accuracy of the acceleration determined from kinematic GPS measurements. Spectral techniques are used to analyze the acceleration in different dynamic environments. Processing methods are discussed at some length, because they affect the accuracy of the results in a major way. As expected, the accuracy is dependent on the averaging period. Standard enors of 1.0 and 0.4 mGal are achievable for moving averages of 1 and 2 minutes, respectively. Maximum values are about 2 and 1 mGal for the same periods.