On Precision Kinematic Accelerations for Airborne Gravimetry

Abstract

Abstract:Advances in accelerometer technology promise many orders of magnitude improvement in sensitivity; which, consequently, also suggest progress in Earth Science applications, such as through new airborne gravimetric systems. However, a new capability for one sensor then usually demands commensurate requirements from auxiliary sensors in order to realize its full potential. Specifically, airborne gravimetry would benefit from improved inertial accelerometry only if the kinematic acceleration derived from vehicle tracking or positioning is equally precise. The latter is investigated in this study to determine the limits in precision due to errors in modeling the numerical derivative and due to errors in the positions, themselves. Simulations with actual aircraft trajectories show that the kinematic acceleration using current positioning capability (that is, GPS or similar satellite navigation systems) can be determined to an accuracy at the sub-milligal level only with sufficient smoothing over intervals of 60 s or longer. The effects of position error still dominate over the model error, and both are many orders of magnitude greater than the predicted precision of state-of-the-art accelerometry. This suggests that airborne gravity field determination likely will profit more if the advances in inertial sensor technology are directed toward gravity gradiometry.

On the Feasibility of Seafloor Topography Estimation from Airborne Gravity Gradients: Performance Analysis Using Real Data

“…Therefore, in addition to the airborne gravimeter, the accuracy of the measured gravity is also affected by the kinematic acceleration derived from aircraft tracking (typically using differentially corrected GPS). Limited by the errors in modeling the numerical derivative and the positioning capabilities of current global navigation satellite systems, the kinematic acceleration can achieve an accuracy of sub-mGal level only with smoothing over intervals of 60s or longer [16]. On the contrary, airborne gravity gradiometry does not need to determine the kinematic acceleration of the aircraft.…”

High accuracy acceleration determination by using multiple GNSS reference stations

“…broadcast ephemeris is always used to calculate satellite velocities and accelerations, and the kinematic accuracy can be estimated using an extended Kalman filter (EKF) [1], however, the accuracy is limited by GNSS error sources, only mm/s level horizontal velocity and mm/s 2 level acceleration can be achieved [2], which cannot match the requirements of high accuracy applications, such as airborne gravity surveying. (2) Single reference station algorithm, double-difference algorithm is always used to eliminate the clock error, including satellite clock bias and receiver clock bias, this method is very effective in short baseline cases [3][4][5][6], unfortunately, with the increase of the baseline length, the estimated accuracy is degraded for the increased distance-dependant GNSS error sources, including ionosphere delay and troposphere delay mainly, because the data processing method is as the same as the real time kinematic (RTK) method, therefore, this method is called the ''RTKderived method'' in the following paragraphs. (3) Multiple reference stations (MRSs) algorithm, over the past decades, the use of multiple reference station network DGPS approach to extend the interreceiver distances has shown great promise [7].…”

An Improved Method for Dynamic Measurement of Deflections of the Vertical Based on the Maintenance of Attitude Reference

“…Second, the differential GNSS technology for calculating the kinematic accelerations is indispensable. Because the acceleration computation is implemented by a second-order differentiator [ 16 ], which is essentially a high pass filter, the GNSS noise will be enhanced. Additionally, it is necessary to establish GNSS reference stations around the survey routes for differential GNSS; however, the reference stations are difficult to setup in some regions.…”