how do digital devices (like phones, computers) keep time? I get clockwork but even my fairy lights have a timer on – how?
In: Technology
Phones get their time from the cellular network. The cellular network in turn gets its time from GPS satellites. GPS satellites get their time from the reference clocks like the atomic clock at the US Naval Observatory (there are a few other reference clocks around the world). The GPS satellites themselves also have atomic clocks on board. GPS time is about as close to “real” time as you can get without being connected directly to the reference clocks.
Computers have a protocol called NTP – Network Time Protocol. NTP is handled in “stratums” or layers. A “stratum 0” server is one of the aforementioned reference clocks or a GPS satellite. A “stratum 1” server is a server that is time synced to a stratum 0 server. I used to have a stratum 1 time server at home because my local server was connected to a GPS receiver that outputted time signals. Then all the computers in the house could time sync off that server. As it stands right now, Microsoft runs some time sync servers as does Apple so their operating systems can sync off those.
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