Status of the International Atomic Time Tai

Abstract

This paper summarizes the methods for establishing the International Atomic T i m e TAI and s t a t e s i t s stability and accuracy. The various factors which limit the quality of TAI a r e considered. Special attention i s given t o some systematic differences between some of the instruments which contribute to TAI, especially to the seasonal effects which were recent l y found.Introduction.

A Kalman filter clock ensemble algorithm that admits measurement noise: corrections and update

“…When Wright [5] added a third noise component representing integrated random walk of frequency (random run FM noise) [6,7], he observed the frequency errors growing linearly and the phase errors quadratically. In fact, it has been known for a long time that composite clocks can develop unbounded frequency errors and need to be steered to external standards [8]. Here we show by example and theory that the IEMx algorithm acting on twocomponent clocks gives results similar to Wright's: changing the initial state estimates changes the frequency errors by a constant value (after a settling period) and the phase errors by a linear function of time.…”