Linear, dynamic estimation and control of OMEGA radio navigation system synchronization

An integrated, dynamic estimation scheme is applied to the problem of synchronizing precision cesium clocks used to control OMEGA signal transmissions from geographically-remote transmitter stations. A discrete Kalman filter combines models of cesium clock error dynamics with OMEGA phase timing measurements to estimate and control intertransmitter synchronization offsets (both phase and phase rate) to an accuracy on the order of 1 μs rms. Auxiliary algorithms perform OMEGA phase measurement preprocessing, including: compensation for propagation anomalies, reciprocal path phase differencing, automatic outlier rejection, dynamic measurement-quality weighting, and time-correlation modeling. Alternative timing measurements (including: satellite/TV, Loran-C, and portable clock) are utilized, as available, to synchronize the entire transmitter system to Coordinated Universal Time (UTC).