Unbiased FIR Estimates vs. the Sawtooth-Corrected GPS-Based Measurements: Experimental Evaluation

We show that, owing to small noise and smoothed excursions, the unbiased FIR filtering algorithm produces more accurate estimates of the TIE model of a local clock than the sawtooth-less GPS-based measurements. The algorithm becomes much more efficient in estimating the fractional frequency offset and higher order states. For the algorithm to work with minimum errors, the optimal time step Tausub opt and number of the points in the average Nsub opt must be ascertained in the sense of the minimum mean-square error MSE for each of the clock states. The relevant dependencies of Nsub opt on Tausub opt are found experimentally for a crystal clock. The trade-off between the estimates and sawtooth-less measurements is illustrated graphically.