The U.S. Naval Observatory (USNO) and other government labs operate atomic clocks that provide the most accurate timekeeping in the world. These clocks send their data to the International Bureau of Weights and Measures (BIPM) in France, which calculates the Coordinated Universal Time (UTC) based on all the data from atomic clocks around the world. The BIPM shares this UTC time with all participating labs, including USNO.
USNO then adjusts its own time scale, UTC(USNO), which is displayed on the master clock in Washington, D.C. This adjusted time is sent to GPS satellites operated by the U.S. Space Force. The satellites use this signal to correct their own less accurate atomic clocks. The corrected GPS time signals are then received by cellphone towers, which use them to synchronize the time on cellphones and smartwatches.
This global timekeeping system relies on the precise functioning of atomic clocks in government labs, ensuring that the time displayed on modern devices is accurate and synchronized worldwide.
Source: https://www.nist.gov/atomic-clocks/how-does-atomic-time-get-your-phone
Keywords: Timekeeping, Atomic clocks, UTC, GPS, Synchronization
