GPS Based Flight Motion Capture

The objective of this study is to analyse Global Navigation Satellite System (GNSS) processing performance, to determine if it is possible, to capture the shape of a flight path of an airborne Synthetic Aperture Radar (SAR) radar, with a precision of less than 5 cm during the time it takes to record a SAR image, a SAR-run, without relying on a local reference receiver. The precision of position is achieved with the GNSS processing method Precise Point Positioning (PPP) which uses satellite information corrections and an extended Kalman filter. The data analysed were GPS observations from test flights with the Carabas 3 SAR helicopter including 12 flights with a total of 182 SAR-runs approximately 1 minute in length. The PPP processing was made by the position processing program RTKLIB. The PPP solution was compared with a Real Time Kinematics (RTK) solution. The average precision was 3.5 cm during a SAR-run. PPP is a precise technique with potential of capturing the flight movements. The implementation of a platform model and of Carrier Phase Ambiguity Resolution (CPAR) is expected to improve the performance.