How do phones keep track off time while off and without internet connection?
In: Technology
Even when your phone is off, there is still a very small circuit that is powered. This circuit, among other critical things, is keeping track of the current time. It consumes very little power, so it doesn’t drain the battery. Even when the battery says it’s dead, there’s enough charge left to maintain these low power critical functions.
Every computer device that keeps time will have a battery somewhere to help it keep time when its main power is gone. Even a desktop computer will have a watch-style battery on the motherboard to keep the circuit going.
One extra advantage that cell phones have is that, if they ever happen to go completely dead, they can set their time back via GPS. The way GPS works, satellites in known positions are broadcasting a signal that contains their time. If you get 3 pings and know the current time, you can figure out your relationship to those 3 satellites and it narrows it down to one point. If you can get pings from 4 satellites though, you can actually narrow down your position *and* the time from them. This is why phones have such accurate timekeeping.
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