Every time you look at the time on your smartphone, you can be sure that it is exact to the second, even on the days when the change between sunny and legal time takes place. But how does the phone automatically change the time without any intervention on your part? The merit is of a sophisticated synchronization system based on atomic watches, network server And satellites. Smartphones constantly update with the Universal coordinated temple or UTCa global reference that is distributed through the NTP protocol (Network Time Protocol). This standard is maintained by extremely precise atomic watches located in specialized workshops or satellite edge, such as those of the system GPS or Galileo. Thanks to Internet connection or at the signal Gnss (Global Navigation Satellite System), the mobile devices receive the exact hour and are adjusted accordingly.
There Automatic regulation of legal hourthen, is performed by aSpecific phone settingwhich must be maintained active so that the device can automatically adapt to the changes provided for by the calendar. If this option is disabled, the transition from calendar time to legal hour – and vice versa – must be performed manually.
How smartphones do the exact hour do
The synchronization of the time reported on the smartphone display takes place through the help of external sources. When the device is connected to Internetreceives the exact time from specialized servers, called time serverwhich distribute a Synchronized signal with atomic watches. The latter measure the time by exploiting the frequency of the oscillations of particular atoms, such as Cesio or hydrogen, which makes them extremely precise. The signal is transmitted from these servers to smartphones via the NTP protocol (Network Time Protocol).
In addition to the terrestrial workshops that host atomic watches and which, therefore, are able to provide the exact time with extreme precision, the servers to which smartphones are connected to synchronize their time can also be on GNSS satellites (Global Navigation Satellite System): These also have atomic watches on board that constantly send signals containing the exact time to the devices on the ground. When a smartphone connects to a GNSS system, it can update your time even without the need to access the Internet, based on the time data received from the satellites.
Because on some smartphones the time does not change automatically: how to activate it
When the moment of the gearbox arrives between calendar and legal time, the adjustment takes place automatically only if the automatic update option of the hour has been left active on the device. If deactivated, in fact, the smartphone will continue to maintain the exact time thanks to the time servers or satellites, but will not carry out the transition to legal or solar time autonomously. To verify that this function is active, on the devices Android go to the section Settings> System> Date and time and, if necessary, activate the options Automatically set the time AndUse the location to set the time zone (taking into account that the wordings and steps to be made may vary according to the version of Android in use). On iPhoneon the other hand, you have to go to the section Settings> General> Date and time and possibly move on On The switch located near the item Automatic.
If the automatic update is activated, the transition tolegal it will happen without them realizing it: in the Night between 29 and 30 March 2025your phones will update the time by bringing it an hour forward, while the October 26, 2025 Thesolar time.
