A Non-differential Approach to the Estimation of GNSS-derived Accelerations. Galileo's Foreseen Impact on Airborne Gravimetry

J.J. Rosales, I. Colomina

Abstract:	Airborne gravimetry is a technique for gravity field determination. Although it was first proposed in the seventies, it became feasible when the GPS navigation system became fully operational. Actually, the performance of airborne gravimetry strongly depends on the GPS technology. One of the key roles that GPS plays in airborne gravimetry, besides positioning, is the estimation of kinematic accelerations. It is known that the kinematic accelerations determination is quite sensitive on issues such as the satellite geometry, the event of cycle slips or on the availability of a reference station. But, as the GNSS scenario is about to change with the European Galileo, the modernization of the GPS and the renewed GLONASS, it is worth to review the current approaches. This paper reviews the current state of kinematic acceleration determination within the frame of airborne gravimetry and proposes an approach taking into account the coming scenario, mainly focusing on Galileo. Airborne gravimetry is a “precise market” application. In this context it is assumed that the cost of high-end equipment is negligible as compared to the additional maneuvering and surveying required by low-cost equipment. There is also no compelling need of real time processing, allowing to analyze and prepare the data (if needed) before its processing. However, logistics and mission planning is a big issue. In terms of logistics, a flexible operation is needed due to the large areas to be surveyed and its accessibility (rainforest, coastal regions or mountainous areas, for example) or adverse climatology. As a precise application, the use of a reference station to meet the accuracy and precision requirements might be essential. This requires a flexible and agile operation of the reference station. This paper considers the use of no reference station. The reason is twofold. First, because in this paper the Galileo contribution in accuracy and precision without differential techniques wants to be explored. The second reason is to fully exploit one of the main advantages of airborne gravimetry. This is, the accessibility to remote areas of difficult access by land. In such scenario, the maintenance and set of a reference station might be difficult if not impossible. In few words, as a first step, the performance of the combined use of Galileo and GPS and its possible impact on improving the logistics and planning of airborne gravimetry missions is of major interest. In order to assess the impact of Galileo, simulated Galileo observations were generated by means of a simulator developed at the Institute of Engineering, Surveying and Space Geodesy of the University of Nottingham. The results presented show the precision of the estimated kinematic accelerations both with GPS alone and GPS and Galileo combined.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	2824 - 2831
Cite this article:	Rosales, J.J., Colomina, I., "A Non-differential Approach to the Estimation of GNSS-derived Accelerations. Galileo's Foreseen Impact on Airborne Gravimetry," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 2824-2831.
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