Time–frequency analysis of the Galileo satellite clocks: looking for the J2 relativistic effect and other periodic variations

• DOI: 10.1007/s10291-021-01094-2
• Publication Date: 2021-02-11T18:05:44Z
• Authors: Valerio Formichella; Lorenzo Galleani; Giovanna Signorile; Ilaria Sesia
• Keywords: Galileo (satellite navigation); Hydrogen maser; Relativistic quantum chemistry; SIGNAL (programming language)

Abstract When observed from the ground, frequency of atomic clocks flying on satellites a Global Navigation Satellite System is referred to as apparent frequency, because it through on-board signal generation chain, propagation path, relativistic effects, measurement system, and clock estimation algorithm. As consequence, affected by periodic variations different origins such as, for example, component J2 effect, due oblateness earth, errors induced orbital errors. We present detailed characterization affecting Galileo clocks, obtained applying time–frequency analysis other processing techniques space data provided European Space Agency. In particular, we analyze one year three Passive Hydrogen Masers, two planes. Time–frequency reveals how spectral components change with time. For confirms that amplitude depends angle between sun plane. Moreover, allows find more precise estimate in agreement prediction general theory relativity, shows suddenly decreases when corresponding correction applied data, thus validating analytical formula used correction.