GPS-Based Relative Navigation in Earth Observation Missions Relying on Cooperative Satellites

The problem of relative navigation of formation flying satellites for remote-sensing applications is addressed in this chapter. Specifically, a filtering scheme is proposed for the determination of relative position and velocity in real time, relying on the cascade combination of an Extended Kalman Filter and a kinematic filter. Since high measurement accuracy is desired both filters process dual-frequency double-difference carrier-phase GPS observables. In addition, the dynamic filter state is augmented with the Vertical Total Electron Content. Filtering scheme performance in terms of accuracy and robustness are evaluated by Monte Carlo simulations on orbital scenarios relevant to considerable Earth remote sensing applications.results shows that centimetre-level average accuracy can be achieved in real-time and it can be maintained in presence of poor GPS satellite geometry.