Composite clocks with 3-state models

Previous analyses of composite clocks have been presented with 2-state clock models for random clock phase and frequency deviations. But Kalman filter estimate errors due to 3-state clock frequency-drift deviations have not been previously presented. I have employed the 3- state Zucca-Tavella clock model to simulate an ensemble of four 3-state clocks. I have found a dominant common component for 3-state clock Kalman filter phase errors with the curvature of a nonlinear low-order polynomial that does not exist for 2-state clocks. Cesium clocks are free of frequency-drift, but rubidium and hydrogen-maser clocks have significant frequency drift. Use of the 3-state clock model, and an understanding of its true and estimated behavior, will facilitate operation of the associated composite clock.