Stability of the Decentralized Estimation in the JTIDS Relative Navigation

The joint tactical information distribution system (JTIDS) includes a relative navigation capability with which each member can estimate its own position by utilizing the broadcast position estimates of other members plus the measured times of arrival of the radio signals. Previous simulation studies of the system have shown that unrestricted ranging between members can produce unstable navigation errors, but a covariance-based hierarchy may be stable. We have succeeded in proving, analytically, the stability of a closely related organization¿a fixed-rank hierarchy. For all ownstate organizations we present time-domain equations for computing estimation-error covariance and for analyzing stability. A simple simulation is able to demonstrate the stability issues.