[JH4]

Why don't the cellphone operators transmit the 'time of day', so mobiles can have an accurate local time displayed, rather than just a free-running clock.
Is there a technical reason ?
Does anyone know ?

[andy1249]

How accurate do you need to be ?

Since the advent of digital watches timekeeping in electronic devices has been very accurate indeed , they shouldn't lose more than a fraction of a second per month if that.

Keeping a channel open to the phone for transmitting a constant time signal to it would cost money and bandwidth that is better spent on its main function of making calls , most likely it would be you paying for it as well.

[tvdavid]

My N95 clock changed on its own

[JH4]

"they shouldn't lose more than a fraction of a second per month if that."

That's on helluva'n accurate device if it only loses a fraction of a second a month ! I don't believe any watch maker can claim that accuracy on a free-running quartz device. Can you name one ? I think about 5 -30 secs a month is the best most can guarantee, whatever you pay !, and that can add up to several minutes of error over a short period. Personally I would rather have radio controlled accuracy as Casio and some others use - which is why I posted this enquiry. ( it also negates having to manually change daylight saving times. ) I can't see why it's so difficult to transmit a time signal via the cellphone network, in the same way that it's beamed from all radio and TV transmitters. ( There is no need to constantly transmit the signal, just a periodic burst when you make a call would be just fine, for instance. Even radio controlled clocks normally only sync. up once a day, which is fine.) I have an old Junghans clock that syncs every hour, but that's not usual with modern radio controlled clocks now.
Anyone else know why the time code is not transmitted ?
( Or maybe it is, and it's just that my cellphone can't recognise the signal..)