Galileo
is an in-development global European satellite navigation and time reference system controlled by a
civilian authority (European Union Agency for the Space Programme, EUSPA). Its purpose is the worldwide
delivery of high-precision navigation data and is similarly structured to the American GPS, Russian GLONASS
and Chinese BeiDou systems. The main differences in the systems lie in their approaches to frequency usage
& modulation and the satellite constellation.
13.1 Time Zones and Daylight Saving Time
GPS System Time is a linear timescale that was synchronized with the international UTC timescale (Coor-
dinated Universal Time) when the satellite system became operational in 1980. Since it has entered service,
however, several leap seconds have been introduced to the UTC timescale to adjust UTC time to irregularities in
the Earth’s rotation. While GPS System Time deviates from UTC time by several seconds for this very reason,
satellite messages do incorporate the number of seconds by which these timescales deviate from one another,
allowing GPS receivers to be synchronized internally with the international UTC timescale.
The receiver’s microprocessor can identify any time zone based on UTC time and automatically apply Day-
light Saving Time adjustments over several years if so configured by the user.
34
Date: June 16, 2022
IMS-GPS182
