Noise Parameter Identification in Ensemble of Atomic Clocks

The paper introduces a parameter identification framework for atomic clock ensembles, where individual clocks are represented by second-order linear stochastic state-space model. The proposed procedure relies exclusively on differential measurements, namely the pairwise phase differences between a designated pivot clock and the remaining ensemble members. The identification targets key parameters for each clock: white and random-walk frequency noise variances, constant frequency drift, and (co)variance of the measurement noise. To identify these parameters, two distinct identification methods are proposed. Their estimation accuracy is rigorously demonstrated via numerical simulations and validated using empirical data from atomic hydrogen maser (AHM) clocks at ESTEC Timing Laboratory.