GNSS Based Kinematic Acceleration Determination for Airborne Vector Gravimetry Methods and Results

C. Kreye, G.W. Hein

Abstract:	An integrated system for airborne gravimetry can be implemented using GNSS observations in order to calculate the kinematic acceleration and inertial measurements for derivation of specific forces. The difference of both components provides the gravity information. If it is taken into account that for most applications an accuracy of 1 mGal (10-5 m/s2) with a spatial resolution of 1 km is required the processing of both data types must be able to decrease the sensor errors in the defined spectral window. Thus the paper investigates the possibilities to externd this spectral window using different sensor constellations, GNSS observations and post processing methods. After a short summary about the general principles of airborne gravimetry the developed sensor configuration of the Institiute of Geodesy and Navigation is described. The general data processing algorithms are mentioned. Then the determination of the specific forces by the inertial sensor is in the center of interest. Possible error sources of high precision strapdown INS are described and investigated with regard to their spectral range of interest for gravity determination. A realistic view on the expected behaviour of the specific force measurements are supported by practical tests in static mode and a real observation situation for airborne gravimetry using data of a new flight test period. The main topic of the paper is the derivation of the kinematic acceleration using GNSS for purposes of airborne gravimetry. At the beginning of this chapter an error analysis of raw GNSS observations are carried out. In the following the three most important methods for deriving accelerations out of GNSS phase measurements are described and compared to each other. Filtering techniques are mentioned allowing optimal results for the kinematic acceleration in the relevant spectral window of airborne gravimetry. Finally the processing methods are tested using some data sets with different error characteristics and observation conditions (static, in-flight). If these results are evaluated and compared in regard to the frequency area of airborne gravimetry on the one hand a statement concerning the best derivation method can be made on the other hand the influence of different GNSS observation errors like receiver noise and atmospheric effects can be estimated. Furthermore the required GNSS data rate is one aspect of this topic. An outlook concerning the next steps in the described airborne gravimetry project terminates the paper.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	2679 - 2691
Cite this article:	Kreye, C., Hein, G.W., "GNSS Based Kinematic Acceleration Determination for Airborne Vector Gravimetry Methods and Results," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 2679-2691.
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