GPS-Based Optimal Kalman Estimation of Time Error, Frequency Offset, and Aging

摘要

Results are presented of studies of different types of optimal and quasi-optimal Kalman filters based on crystal and rubidium oscillators using reference timing signals from the Motorola GPS UT + Oncore Timing receiver. Filter equations are considered for different definitions of their coefficients, and the filter output signal and its statistics are investigated in time under real conditions. Various Kalman algorithms and corresponding optimal filter structures intended for crystal and rubidium oscillators are discussed. Three- dimensional Kalman filters intended for optimal estimation of time error, frequency offset, and frequency aging are considered based on the oscillator signal model. One application is the synchronization needs of digital communication networks and metrology. Results are given for the measured data and estimates are compared with respect to a quartz crystal oscillator. Practical results are considered of the Kalman filter's use in application to an oven-controlled quartz crystal oscillator (OCXO) with an AT-cut resonator. Plots of the original and filtered processes are discussed for the different approaches to definition of the Kalman filter coefficients. Estimates are also given for the filtering errors and the processing rate.