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How does timezone get set?
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Matt Simpson
Jan 9, 2012, 1:36:00 PM1/9/12
to
When an iPhone is set for automatic time setting
(Settings->General->Date/Time->Set Automatically)
how does it decide what timezone to use? Is it computed based on the
phone's location? Or does the cellular carrier tell it what time zone
it's in?
I just noticed that my iPhone has the wrong timezone when I'm at home.
It says Chicago, which is in CST. When I'm at work, about 20 miles
away, it says New York, which is in EST. (I'm actually in Kentucky, but
New York is the correct timezone. Atlanta is another city in the
available list that would be correct).
At home, the Maps app shows my correct location, so the phone knows
exactly where I am. And I'm not anywhere close to a time zone boundary.
The location that it correctly shows is solidly in Eastern, so if the
phone knows where I am, it should know what time zone I'm in, unless
something else is lying to it.
Obviously, I'm being served by a different cell tower at home. So if
the phone is accepting the timezone from the cell carrier, maybe AT&T
just doesn't know where its tower is.
(Settings->General->Date/Time->Set Automatically)
how does it decide what timezone to use? Is it computed based on the
phone's location? Or does the cellular carrier tell it what time zone
it's in?
I just noticed that my iPhone has the wrong timezone when I'm at home.
It says Chicago, which is in CST. When I'm at work, about 20 miles
away, it says New York, which is in EST. (I'm actually in Kentucky, but
New York is the correct timezone. Atlanta is another city in the
available list that would be correct).
At home, the Maps app shows my correct location, so the phone knows
exactly where I am. And I'm not anywhere close to a time zone boundary.
The location that it correctly shows is solidly in Eastern, so if the
phone knows where I am, it should know what time zone I'm in, unless
something else is lying to it.
Obviously, I'm being served by a different cell tower at home. So if
the phone is accepting the timezone from the cell carrier, maybe AT&T
just doesn't know where its tower is.
nospam
Jan 9, 2012, 2:24:45 PM1/9/12
to
In article
<net-news69-4E0BD...@news.eternal-september.org>, Matt
> I just noticed that my iPhone has the wrong timezone when I'm at home.
> It says Chicago, which is in CST. When I'm at work, about 20 miles
> away, it says New York, which is in EST. (I'm actually in Kentucky, but
> New York is the correct timezone. Atlanta is another city in the
> available list that would be correct).
odd. does this happen with other cellphones (friends, coworkers, etc.),
including android dumbphones and other iphones?
> At home, the Maps app shows my correct location, so the phone knows
> exactly where I am. And I'm not anywhere close to a time zone boundary.
> The location that it correctly shows is solidly in Eastern, so if the
> phone knows where I am, it should know what time zone I'm in, unless
> something else is lying to it.
>
> Obviously, I'm being served by a different cell tower at home. So if
> the phone is accepting the timezone from the cell carrier, maybe AT&T
> just doesn't know where its tower is.
it could be at&t. the time they send is usually off by up to a minute,
sometimes more, so it wouldn't surprise me if the time zone was wrong.
i've seen time zone problems when daylight saving time changes, but
usually for no more than a few hours.
<net-news69-4E0BD...@news.eternal-september.org>, Matt
Simpson <net-n...@jmatt.net> wrote:
> When an iPhone is set for automatic time setting
> (Settings->General->Date/Time->Set Automatically)
> how does it decide what timezone to use? Is it computed based on the
> phone's location? Or does the cellular carrier tell it what time zone
> it's in?
cellular networks send the time & timezone.
> When an iPhone is set for automatic time setting
> (Settings->General->Date/Time->Set Automatically)
> how does it decide what timezone to use? Is it computed based on the
> phone's location? Or does the cellular carrier tell it what time zone
> it's in?
> I just noticed that my iPhone has the wrong timezone when I'm at home.
> It says Chicago, which is in CST. When I'm at work, about 20 miles
> away, it says New York, which is in EST. (I'm actually in Kentucky, but
> New York is the correct timezone. Atlanta is another city in the
> available list that would be correct).
including android dumbphones and other iphones?
> At home, the Maps app shows my correct location, so the phone knows
> exactly where I am. And I'm not anywhere close to a time zone boundary.
> The location that it correctly shows is solidly in Eastern, so if the
> phone knows where I am, it should know what time zone I'm in, unless
> something else is lying to it.
>
> Obviously, I'm being served by a different cell tower at home. So if
> the phone is accepting the timezone from the cell carrier, maybe AT&T
> just doesn't know where its tower is.
sometimes more, so it wouldn't surprise me if the time zone was wrong.
i've seen time zone problems when daylight saving time changes, but
usually for no more than a few hours.
Wes Groleau
Jan 9, 2012, 8:17:39 PM1/9/12
to
On 01-09-2012 14:24, nospam wrote:
> it could be at&t. the time they send is usually off by up to a minute,
> sometimes more, so it wouldn't surprise me if the time zone was wrong.
Every time I've checked (not very often), my AT&T iPhone is about three
> it could be at&t. the time they send is usually off by up to a minute,
> sometimes more, so it wouldn't surprise me if the time zone was wrong.
seconds off.
--
Wes Groleau
A child’s funeral
http://Ideas.Lang-Learn.us/barrett?itemid=1583
nospam
Jan 9, 2012, 8:23:49 PM1/9/12
to
In article <jeg3jj$deo$2...@dont-email.me>, Wes Groleau
it's still wrong. sprint & verizon, on the other hand, are exact (they
have to be).
<Grolea...@FreeShell.org> wrote:
> > it could be at&t. the time they send is usually off by up to a minute,
> > sometimes more, so it wouldn't surprise me if the time zone was wrong.
>
> Every time I've checked (not very often), my AT&T iPhone is about three
> seconds off.
my at&t phone is usually about 20-30 seconds off. not a huge deal, but
> > it could be at&t. the time they send is usually off by up to a minute,
> > sometimes more, so it wouldn't surprise me if the time zone was wrong.
>
> Every time I've checked (not very often), my AT&T iPhone is about three
> seconds off.
it's still wrong. sprint & verizon, on the other hand, are exact (they
have to be).
Wes Groleau
Jan 9, 2012, 8:27:52 PM1/9/12
to
On 01-09-2012 20:23, nospam wrote:
> my at&t phone is usually about 20-30 seconds off. not a huge deal, but
> it's still wrong. sprint& verizon, on the other hand, are exact (they
> my at&t phone is usually about 20-30 seconds off. not a huge deal, but
> have to be).
Been a couple of years since I told Sprint to get out of my life, but
back then, they were always two or three minutes.
Probably a geographic difference.
--
Wes Groleau
“There are more people worthy of blame
than there is blame to go around."
Chris Blunt
Jan 10, 2012, 1:06:48 PM1/10/12
to
On Mon, 09 Jan 2012 20:17:39 -0500, Wes Groleau
<Grolea...@FreeShell.org> wrote:
>On 01-09-2012 14:24, nospam wrote:
>> it could be at&t. the time they send is usually off by up to a minute,
>> sometimes more, so it wouldn't surprise me if the time zone was wrong.
>
>Every time I've checked (not very often), my AT&T iPhone is about three
>seconds off.
I get similar results to you. I often check my iPhone time against the
<Grolea...@FreeShell.org> wrote:
>On 01-09-2012 14:24, nospam wrote:
>> it could be at&t. the time they send is usually off by up to a minute,
>> sometimes more, so it wouldn't surprise me if the time zone was wrong.
>
>Every time I've checked (not very often), my AT&T iPhone is about three
>seconds off.
Greenwich Time Signal broadcast on the radio station I listen to in
the mornings, and its always correct to within a second or two. It
would be interesting to know the reference source against which the
iPhone calibrates its clock.
Chris
Wes Groleau
Jan 10, 2012, 9:08:44 PM1/10/12
to
On 01-10-2012 13:06, Chris Blunt wrote:
> the mornings, and its always correct to within a second or two. It
> would be interesting to know the reference source against which the
> iPhone calibrates its clock.
It's set by a signal from AT&T via whatever tower your close to.
> the mornings, and its always correct to within a second or two. It
> would be interesting to know the reference source against which the
> iPhone calibrates its clock.
--
Wes Groleau
People would have more leisure time if it weren't
for all the leisure-time activities that use it up.
— Peg Bracken
Wes Groleau
Jan 10, 2012, 9:09:59 PM1/10/12
to
On 01-10-2012 13:06, Chris Blunt wrote:
> I get similar results to you. I often check my iPhone time against the
> Greenwich Time Signal broadcast on the radio station I listen to in
P.S. There's a free app called Emerald Time (I think that's the name)
> Greenwich Time Signal broadcast on the radio station I listen to in
that will use NTP to show how far off your phone is.
Chris Blunt
Jan 11, 2012, 4:46:06 PM1/11/12
to
On Tue, 10 Jan 2012 21:08:44 -0500, Wes Groleau
<Grolea...@FreeShell.org> wrote:
>On 01-10-2012 13:06, Chris Blunt wrote:
>> the mornings, and its always correct to within a second or two. It
>> would be interesting to know the reference source against which the
>> iPhone calibrates its clock.
>
>It's set by a signal from AT&T via whatever tower your close to.
Are you sure? I'm several thousand miles away from the nearest AT&T
<Grolea...@FreeShell.org> wrote:
>On 01-10-2012 13:06, Chris Blunt wrote:
>> the mornings, and its always correct to within a second or two. It
>> would be interesting to know the reference source against which the
>> iPhone calibrates its clock.
>
>It's set by a signal from AT&T via whatever tower your close to.
tower.
I assume you mean it's set by the mobile network operator, which is
the method by which many other cellphones adjust their time. I'm a bit
reluctant to believe this is the way the iPhone does it because I have
another (Nokia) phone operating on the same network which is also set
to adjust it's time automatically but is consistently several seconds
out. If both phones were obtaining their time reference from the
mobile network you would expect them to have the same degree of error.
I was wondering if perhaps the iPhone uses a NTP time reference source
when it has an active internet connection available.
Chris
nospam
Jan 11, 2012, 5:00:43 PM1/11/12
to
In article <d2vrg7pet57rovp96...@4ax.com>, Chris Blunt
it *should* use ntp, but doesn't. if it did, wifi-only devices such as
ipads and ipod touches could maintain an accurate time rather than
drift. i've seen my ipad grow to several minutes off until i sync it at
which point it gets updated from the computer's time.
<ma...@nospam.com> wrote:
> I was wondering if perhaps the iPhone uses a NTP time reference source
> when it has an active internet connection available.
it's from the cellular network.
> I was wondering if perhaps the iPhone uses a NTP time reference source
> when it has an active internet connection available.
it *should* use ntp, but doesn't. if it did, wifi-only devices such as
ipads and ipod touches could maintain an accurate time rather than
drift. i've seen my ipad grow to several minutes off until i sync it at
which point it gets updated from the computer's time.
Alan Browne
Jan 11, 2012, 5:49:26 PM1/11/12
to
On 2012-01-11 16:46 , Chris Blunt wrote:
> I was wondering if perhaps the iPhone uses a NTP time reference source
> when it has an active internet connection available.
It's not clear to me.
> I was wondering if perhaps the iPhone uses a NTP time reference source
> when it has an active internet connection available.
I have an App called Time which allows me to enter an ntp address (so I
use one nearby). It's not clear if this changes the system ntp or is a
separate process using a separate ntp server while the iPhone uses its own.
Generally Mac's come set to the super regional Apple ntp server.
(time.apple.com, time.asia.apple.com, time.euro.apple.com). I assume
the iPhone uses those same defaults. (I set my Mac to a local one).
--
"We demand rigidly defined areas of doubt and uncertainty."
Douglas Adams - (Could have been a GPS engineer).
JF Mezei
Jan 11, 2012, 5:54:06 PM1/11/12
to
Alan Browne wrote:
> I have an App called Time which allows me to enter an ntp address (so I
> use one nearby). It's not clear if this changes the system ntp or is a
> separate process using a separate ntp server while the iPhone uses its own.
If you read the docunention, it is clearly wirtten that because IOS does
> I have an App called Time which allows me to enter an ntp address (so I
> use one nearby). It's not clear if this changes the system ntp or is a
> separate process using a separate ntp server while the iPhone uses its own.
not allow an application to change the time, the "Time" application does
not change the iphone's time. It mereley reports the offet to the reat
(ntp obtained) time.
Fergus McMenemie
Jan 16, 2012, 4:48:56 PM1/16/12
to
Wes Groleau <Grolea...@FreeShell.org> wrote:
> > I get similar results to you. I often check my iPhone time against the
> > Greenwich Time Signal broadcast on the radio station I listen to in
>
> P.S. There's a free app called Emerald Time (I think that's the name)
> that will use NTP to show how far off your phone is.
Emerald time is good. But it ony reports using NTP how out the Iphone
> > I get similar results to you. I often check my iPhone time against the
> > Greenwich Time Signal broadcast on the radio station I listen to in
>
> P.S. There's a free app called Emerald Time (I think that's the name)
> that will use NTP to show how far off your phone is.
is. Travelling to/from different time zones via the channel tunnel, I
was badly caught out several times by the Iphone not changing time zone
properly. THERE IS A BUG SOMEWHERE. But I was not able to pin down what
was going on. In some cases as I roamed about within Europe I could see
the clock jump as I roamed to different networks. I suspect there is a
glitch within IOS which stops the Iphone from properly interpreting what
is being sent out by the local tower.
nospam
Jan 16, 2012, 6:21:09 PM1/16/12
to
In article <1kdzfoo.1oqq4pq14ggjg8N%fer...@twig-me-uk.not.here>, Fergus
time zone issues too.
McMenemie <fer...@twig-me-uk.not.here> wrote:
> Emerald time is good. But it ony reports using NTP how out the Iphone
> is. Travelling to/from different time zones via the channel tunnel, I
> was badly caught out several times by the Iphone not changing time zone
> properly. THERE IS A BUG SOMEWHERE. But I was not able to pin down what
> was going on. In some cases as I roamed about within Europe I could see
> the clock jump as I roamed to different networks. I suspect there is a
> glitch within IOS which stops the Iphone from properly interpreting what
> is being sent out by the local tower.
the only glitch is that apple does not understand time zones. macs have
> Emerald time is good. But it ony reports using NTP how out the Iphone
> is. Travelling to/from different time zones via the channel tunnel, I
> was badly caught out several times by the Iphone not changing time zone
> properly. THERE IS A BUG SOMEWHERE. But I was not able to pin down what
> was going on. In some cases as I roamed about within Europe I could see
> the clock jump as I roamed to different networks. I suspect there is a
> glitch within IOS which stops the Iphone from properly interpreting what
> is being sent out by the local tower.
time zone issues too.
Wes Groleau
Jan 16, 2012, 9:56:16 PM1/16/12
to
On 01-16-2012 16:48, Fergus McMenemie wrote:
>> > P.S. There's a free app called Emerald Time (I think that's the name)
>> > that will use NTP to show how far off your phone is.
> Emerald time is good. But it ony reports using NTP how out the Iphone
That's what I said.
>> > P.S. There's a free app called Emerald Time (I think that's the name)
>> > that will use NTP to show how far off your phone is.
> Emerald time is good. But it ony reports using NTP how out the Iphone
Dillon Pyron
Jan 18, 2012, 1:33:53 PM1/18/12
to
Thus spake nospam <nos...@nospam.invalid> :
My AT&T iPhone, AT&T home phone (not Uverse), my TW cable box and my
Vista laptop all disagree by about 45 seconds. Never consistently!
I "trust" my laptop the most. It is consistenly late from my GPS,
which I credit as the most "accurate" and "precise". When I have 6 or
more sattelites in view.
It depends on the delays from the source to the transmitter to you.
Any Unix sysdamins out there? My answer to most questions of "can
you?" or "why does it?" is almost always "it depends". I was told
long ago in SunOS school that that is the correct answer. Unless it's
a multiple choice question. The it's "yes".
--
- dillon I am not invalid
So Kim Jung Ill shows up at the barbecue. "Wait,"
says Qadaffi, "you don't have any peircings." "If you
starve your people enough they'll be too weak to rebbel."
"You have the same number of holes in your head as when
you were born," says bin Laden. "My compound had radar
and antiacraft misslles." "Your neck," shouted Hussein,
"it's the same length." "I didn't piss on W's father."
"Then what happened?" the three asked. "Damned counterfiet
Lipitor and insulin!"
Vista laptop all disagree by about 45 seconds. Never consistently!
I "trust" my laptop the most. It is consistenly late from my GPS,
which I credit as the most "accurate" and "precise". When I have 6 or
more sattelites in view.
It depends on the delays from the source to the transmitter to you.
Any Unix sysdamins out there? My answer to most questions of "can
you?" or "why does it?" is almost always "it depends". I was told
long ago in SunOS school that that is the correct answer. Unless it's
a multiple choice question. The it's "yes".
--
- dillon I am not invalid
So Kim Jung Ill shows up at the barbecue. "Wait,"
says Qadaffi, "you don't have any peircings." "If you
starve your people enough they'll be too weak to rebbel."
"You have the same number of holes in your head as when
you were born," says bin Laden. "My compound had radar
and antiacraft misslles." "Your neck," shouted Hussein,
"it's the same length." "I didn't piss on W's father."
"Then what happened?" the three asked. "Damned counterfiet
Lipitor and insulin!"
Matt Simpson
Jan 19, 2012, 4:09:50 PM1/19/12
to
Back to my original question, which involved the timezone and not the
precise time, it gets curiouser and curiouser.
I'm not completely convinced that the cell tower is telling the iPhone
what timezone it's in. Or to be more correct, maybe the cell tower is
telling it, but the iPhone is ignoring that in favor of some other
source.
For one thing, I've noticed that the timezone doesn't change immediately
when I get home. It stays correct for a while. It seems to change
overnight.
Also, the displayed time doesn't seem to change zones while the screen
is locked. When I picked up my phone this morning, it had the correct
time. As soon as I unlocked the screen, the time dropped back an hour.
After being at work about an hour, I noticed the time displayed on the
locked screen was still an hour behind. I unlocked the screen and it
immediately jumped ahead.
There's something very mysterious happening overnight that's causing my
phone to think it's in a different timezone. At this point, I'm not
even sure it's related to location. I haven't spent a night with the
phone somewhere else to see if it changes timezones elsewhere.
precise time, it gets curiouser and curiouser.
I'm not completely convinced that the cell tower is telling the iPhone
what timezone it's in. Or to be more correct, maybe the cell tower is
telling it, but the iPhone is ignoring that in favor of some other
source.
For one thing, I've noticed that the timezone doesn't change immediately
when I get home. It stays correct for a while. It seems to change
overnight.
Also, the displayed time doesn't seem to change zones while the screen
is locked. When I picked up my phone this morning, it had the correct
time. As soon as I unlocked the screen, the time dropped back an hour.
After being at work about an hour, I noticed the time displayed on the
locked screen was still an hour behind. I unlocked the screen and it
immediately jumped ahead.
There's something very mysterious happening overnight that's causing my
phone to think it's in a different timezone. At this point, I'm not
even sure it's related to location. I haven't spent a night with the
phone somewhere else to see if it changes timezones elsewhere.
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