Orbit/covariance estimation and analysis (ocean) determination for satellites

The orbit/covariance estimation and analysis (OCEAN) technique utilizes ground station observations collected from satellites passing overhead and estimates the positions, velocities, and other parameters of multiple satellites. It also estimates parameters for other elements, such as the locations of ground stations and measurement biases. The technique utilizes recorded observations (e.g., range, Doppler) and measurements from various sources as inputs to a weighted least squares batch estimation algorithm used in iterative fashion to estimate each parameter, with or without a priori knowledge of the errors involved with each observed parameter. The process is completed once the residual, the difference between the estimated parameter and the observed parameter, satisfies the tolerance defined by the user. Using the results of the estimation process or a predefined initial condition file, the OCEAN program can also generate a predicted trajectory (i.e., ephemeris) for the satellite(s) from a specified initial time to a final time. The resulting epheremerides can be output in a predefined file format chosen by the user.