单站GPS确定航空重力测量载体运动加速度的方法与结果分析

飞机运动加速度的测量精度是制约航空重力测量技术发展的主要障碍之一。相较于传统动态差分GPS（differential GPS，DGPS）技术，所提方法采用单站测量模式，无需布设地面基准站。首先通过相位历元间差分解得高精度历元间位移序列，然后结合泰勒一阶中心差分获得载体加速度，重点分析了卫星轨道和卫星钟差对加速度估计的影响，结果表明，不同卫星轨道产品对加速度估计影响较小，而卫星钟差采样率对加速度估计的影响很大。结合中国陕西省境内的GT-2A航空重力测量系统飞行实测数据，利用单站法解算的加速度联合重力和姿态数据解算重力扰动结果与DGPS解算的重力扰动符合较好，当滤波长度为100 s时，两者互差优于1.0 mGal。重力扰动交叉点不符值网平差后，均方根（root mean square，RMS）为1.13 mGal。与地面重力实测值比较的结果表明，所提方法与DGPS方法在精度上基本一致，说明单站法标量航空重力测量是可行的。

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.