Resumen de A network approach for strapdown inertial kinematic gravimetry
María Assumpció Termens Perarnau
Compared to the conventional ground measurement of gravity, airborne gravimetry is more efficient and cost-effective. Especially, the combination of GPS and INS is known to show very good performances recovering the gravity signal in the range of medium frequencies (1--100 km). The processing of airborne gravity data traditionally consists of various independent steps, such as filtering, gridding and adjustment of misfits at crossover points. Each of these steps may introduce errors that accumulate in the course of processing. Mainly, the extraction of gravity anomalies from airborne strapdown INS gravimetry has been based on the state-space approach (SSA), which has many advantages but displays a serious disadvantage, namely, its very limited capacity to handle space correlations (like the rigorous treatment of crossover points). This dissertation explores an alternative approach through the well known geodetic network approach, where the INS differential mechanisation equations are interpreted as observation equations of a least-squares parameter estimation problem. In numerical terms, the INS equations are solved by a finite difference method where the initial/boundary values are substituted with the appropriated observation equations. The author believes that the above approach has some advantages that are on worth exploring; mainly, that modelling the Earth gravity field can be more rigorous than with the SSA and that external information can be better exploited. It is important to remark that this approach cannot be applied to real-time navigation. However, here we are not trying to solve a navigation problem but a geodetic one. A discussion of the different ways to handle with the associated system of linear equations will be described and some practical results from simulated data are presented and discussed.
