Abstract
An airplane carries gradiometers which measure all components of the gravity-gradient tensor. The airplane is flying at constant speed and altitude in a constant direction, and good estimates are desired of the gravity deflection along and perpendicular to the flight direction. The gravity variations are described by the top three layers of a 5-layear statistical model due to Heller. The estimation is analyzed by two separate methods: (i) a low-order state-space model is constructed to approximate the Heller model and to apply Kalman filter: (ii) Wiener filter theory is used to obtain asymptotic results for high gradiometer accuracy, corroborating the results obtained in (i).
