Comparing Clock Steering Technique Performances in Simulations and Measurements

Abstract

Robust, reliable and stable time scales are needed in a wide field of applications, i.e. in the Global Navigation Satellite System (GNSS) sector. The performance of GNSSs for ground users in terms of navigation is directly connected with the accuracy and stability of the related time scales as errors in time directly propagate into the precision of positioning on earth. Hence, in order to achieve improved robustness as well as stability, future GNSS time concepts should be based on clock ensembles and not on a single clock signal. This concept is already used for prominent time scales such as GPS system time or Universal Time Coordinated. However, in order to generate a physical output of such clock ensembles, a single clock signal is steered towards the composite clock solution. Thus, the steering process has significant impact on the overall performance of the realization of a time scale generated by an ensemble of clocks. Hence, this paper will present our latest results on clock steering. We will compare simulations with real measurements where one clock is steered to another. We used a Kalman filter approach predicting future clock states and the linear quadratic regulator as well as pole placement to calculate the required steering parameters. The simulations for a variety of different steering parameters are then subsequently compared to real clock measurements to verify the applicability and the performance of the different steering techniques. This can be seen as an intermediate step towards realizing a composite clock consisting of different clock types in future investigations.