how do the clocks in cars, stoves, phones (I guess?) know what time it is? Is it signals from satellites or something?
In: Technology
Most of the clocks in devices like cars and stoves have to be set manually. NIST’s atomic clocks *do* transmit a time signal over radio that the public can use, but most clock manufacturers don’t bother putting in the hardware that would be needed to read the signal.
Cell phones actually have a couple of different ways they could set the time. Most, I believe, set their time from signals transmitted by the carrier as part of the cellular network. They could set their time using Internet time servers, but that would require using data (this is what most PCs do nowadays). They could also take their time from GPS or similar services, which transmit time signals from satellites (this is what dedicated GPS devices typically do). Or they could use the NIST radio signal I mentioned above. But I think they typically use the wireless carrier’s signal if they can.
In cars and stoves, unless they’re support be and fancy, you have to manually set the clock when you get it. Car clocks are notoriously bad and wander all over the place. It takes a surprisingly amount of tweaking to get a car clock accurate.
For clocks in cars and stoves you have to set the time yourself. Once you’ve set it once, you don’t have to bother with it unless the time changes (daylight savings, driving through another time zone, etc).
Cars and stoves are not connected to anything wirelessly, so they can’t actually communicate enough to get the time automatically the way your phone can.
I’m not familiar with clocks in stoves, but most clocks in devices connect to a time server over the internet to adjust their times. A time server is a computer which reads time from a reference clock (such as atomic clocks) and distributes that information to connecting/querying devices
That connection could be cellular, WiFi or satellites
Edit: just to add, before the internet and the “internet of things” frameworks, I recall we used to get the _official/government time_ on TV channels or on radio stations with which we used to adjust our clocks if any of them were out of pace
Most clocks, except for those you set manually, trace their way back to three hyper accurate atomic clocks maintained by NIST. For technical reasons, GPS needs a freakishly accurate time signal, so the GPS satellites get their time info from those clocks and have their own hyper-accurate clocks onboard. Thus anything with a GPS chip can get time directly from the GPS signal.
For other (unrelated) technical reasons, cell phone towers also need to be very precisely synchronized, so *they* use GPS to synchronize with each other. As a side effect, your phone can get what’s effectively GPS time via the cell network even if the phone itself doesn’t have a GPS chip.
You have to set the clock on a stove or car yourself. After that, it’s just a matter of the stove or car ***keeping*** the time.
On a stove, this happens by the clock circuit always being powered from the wall plug.
On a car, this happens by the clock circuit always being powered from the car battery. If someone disconnects the car battery or the car battery goes dead, the clock will “forget” the time.
On a cell phone, the cellular towers tell the phone what time it is, and then the phone can continue to do its own timekeeping if you put it into airplane mode or otherwise have no signal.
On some clocks like a fancy alarm clock or a 1990s-2000s era TV, the clock can listen for a time code hidden in a radio signal.
As for satellites… GPS devices set their time by satellite.
Funny enough, the “GPS signal” that a GPS uses to figure out where it is, is very little more than a time-code. The GPS receives timecodes from multiple satellites and figures out its location based on how long it took each satellite’s code to reach it.
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