4-dimensional metrology architecture for satellite clusters using crosslinks

The interest in employing satellite clusters for multiple space-based missions typically requires significant cluster-level relative metrology. The metrology must be 4-dimensional in general (3D space and time). A two-level metrology architecture and initial analysis using a combination of carrier-phase GPS measurements combined with intersatellite crosslinks is described. The crosslink approach generalizes the two-way time transfer methodology to n-way. This measurement approach simultaneously determines both separation and relative timing errors between spacecraft. As more satellites are added to the system, the number of additional independent measurements increases faster than the number of variables to be estimated thus improving performance and robustness