How accurate is Apple Watch?
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Here's how Apple synchronized all your Apple Watches
"Lynch explained that not only is the Apple Watch extraordinarily accurate, but take any two Apple Watches and hold them side-by-side and you will see the second hands moving in perfect unison.
"First of all, we’ve curated our own network time servers around the world," said Lynch. There are, by his count, 15 such "Stratum One"-level Network Time Servers (NTP) (one level down from an atomic clock), scattered around the world. They're all housed in buildings with GPS antennas on the roof that talk, you guessed it, to GPS satellites orbiting the earth, which all get their time information from the U.S. Naval Observatory. In other words, those satellites are all getting their times from one, big orbiting system.
The servers then communicate with iPhones around the world, via the Internet, which in turn communicates with Bluetooth-connected Apple Watches. Of course, even that hand-off has to be managed. "We do corrections for time delay in communication," said Lynch.
Apple also designed the Apple Watch to be an exquisitely accurate timepiece, building in what's known as a crystal temperature-control oscillator. Its job is to manage the vagaries of extreme temperatures, to compensate for drift and keep the Apple Watch time-accurate. Lynch actually told us that "as a piece of hardware,
[Apple Watch is] far more accurate as a timekeeping device than the iPhone," said Lynch. It's actually four times better, he noted."
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