Computation of aircraft geometric height under radar surveillance

A radar system for geometric height estimation of civil aircraft is described. The system consists of one standard or mode S secondary surveillance radar (SSR) and one omnidirectional antenna sited away from SSR under an airplane. The geometric height is derived by trilateration. Systematic errors are compensated for by deriving the profile of the effect on height measurements of the bias in range measurements. A curve-fitting technique is then used, which estimates both the geometric height and any non-zero systematic errors     

Three-dimensional tracking using on-board measurements

The development of a three-dimensional tracker using onboard measurements is described. A system model based on aircraft dynamics is derived. A full 3-D tracking system that can be split, with a part operating onboard and a part operating on the ground, is developed. Attitude angle and aircraft airspeed measurements are processed to estimate the components of the aircraft velocity with respect to the surrounding air. These are then used to obtain estimates of the aircraft position and ground speed. The tracker is designed so that the number of quantities transmitted to the ground station is kept to a minimum. The tracker was evaluated with real data and was found to perform well, resulting in a considerable improvement over the conventional first-order Kalman filter