Table of Contents
International Journal of Navigation and Observation
Volume 2008, Article ID 524317, 5 pages
Research Article

Identifying Nonstationary Clock Noises in Navigation Systems

1Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129, Italy
2INRIM, Strada della Cacce 91, Torino 10135, Italy

Received 9 August 2007; Accepted 27 December 2007

Academic Editor: Demetrios Matsakis

Copyright © 2008 Lorenzo Galleani and Patrizia Tavella. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The stability of the atomic clocks on board the satellites of a navigation system should remain constant with time. In reality there are numerous physical phenomena that make the behavior of the clocks a function of time, and for this reason we have recently introduced the dynamic Allan variance (DAVAR), a measure of the time-varying stability of an atomic clock. In this paper we discuss the dynamic Allan variance for phase and frequency jumps, two common nonstationarities of atomic clocks. The analysis of both numerical simulations and experimental data proves that the dynamic Allan variance is an effective way of characterizing nonstationary behaviors of atomic clocks.