how does a smartphone know what time is it?

[Nagby]

hi, so on a PC to get the time you need a quartz, a battery, and also have to tell what time is time but only once

on a smartphone i guess the battery is kept at a certain level so there is never 0W to the hardware (but then what happen when you remove it?) but i see no room for a quartz (in ifixit teardowns for example)

i know that there is a radio signal telling the time, but it isn't always caught and there can be a long delay before getting it (at least i have a timer which use it, and sometime it takes several houres to find the right time)

and anyway, without a quartz, it would have to always take this signal, or use internet to know the time, it won't know how much a second last

+ i think a quartz is mandatory to set chips clock

so is there a very tiny quartz? what size?

or is there another way to get time?

[Gung Pow Chicken]

By communicating with the cellphone towers.

[Johannes_Lazor]

Smartphones usally go after the atomic clocks.

I know there is one in Berlin, Germany that most smartphones in EU go after.

[AlwaysFSX]

By communicating with the cellphone towers.

Yups, this.

[Gung Pow Chicken]

It receives it through the network it's connected to, when you completely take it off both networks and turn it off. Whatever time passes will cause it to be incorrect so long as it can't connect to anything. If you just leave it on it will continue to be on time because there is nothing to interrupt it.

[Nagby]

so it have to re-get time for each seconds?

and it use this to set chips clock as well?

[Gung Pow Chicken]

so it have to re-get time for each seconds?

and it use this to set chips clock as well?

Once it connects to the tower it gets verified. Through that process it just continues along with the time track, the only way phones are wrong is to disable communication to both cell towers and internet. But you must also remove the battery otherwise it will stay current.

[Johannes_Lazor]

so it have to re-get time for each seconds?

and it use this to set chips clock as well?

The signal from the atomic clocks will be sent you your phone and the phone syncs to the atomic clock

In berlin if you are from EU.

If you dont have any cconnection your phone only go after its own clock and wont sync.

[Gung Pow Chicken]

Most phones have the DST for the next like 100 years but it also depends on what region you are in and if you travel. Some states in the Murica didn't actually adapt to the time changes. Which in my opinion should just be abolished. All it does is make me tired for a week while my body adapts to the time change.

[Nagby]

so it has some component to know how much a second last, if it can keep going after syncing

but quartz on desktop motherboard are pretty big for a smartphone (~12x4x5mm)

[Johannes_Lazor]

so it has some component to know how much a second last, if it can keep going after syncing

but quartz on desktop motherboard are pretty big for a smartphone (~12x4x5mm)

I think smartphones has something else than a quartz crystal.

I think a smartphone simply go after the CPU cycles or have a microprocessor that is dedicated to the clock.

[steffen_anywhere]

so it have to re-get time for each seconds?

and it use this to set chips clock as well?

 

Nonono. There is a high precision electric oscillator that will set clock speeds. The time is only synced once in a while afaik.

 

EDIT: Well I don't know if the oscillators used in laptops are still quartz-based, but I do think so.

[Maxibonbits]

Network Time Protocol (NTP)

http://en.wikipedia.org/wiki/Network_Time_Protocol

[Nagby]

Nonono. There is a high precision electric oscillator that will set clock speeds. The time is only synced once in a while afaik.

 

EDIT: Well I don't know if the oscillators used in laptops are still quartz-based, but I do think so.

well that is mostly what i am wondering, what component in a smartphone give the rythme of work to everything