Applications of Variance Factors in Evaluations of Trajectory Solution Accuracies.

摘要

This report presents an expository description of certain statistics, called 'variance factors' herein. These statistics play a dominant role whenever accuracies of trajectory coordinate solutions are evaluated since they effectively scale the standard deviations and covariances of the coordinate solutions. Conventionally, standard deviations (often called 'GDOPs' or 'uncertainties' in range parlance) are used to evaluate solution accuracies so that 'variance factors' should be acknowledged whenever uncertainties are calculated. This is not always the case, sometimes 'variance factors' are implicitly neglected. For example, the program called NITE that is currently used by SAMTEC to determine trajectory solutions and uncertainties has no capability to calculate variance factors; consequently, uncertainties of trajectory solutions calculated by NITE may not be appropriately scaled (i.e., compared to unity).