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From: Doug Jantzer on 14 Jul 2010 22:04
My iPhone is consistently 18 seconds ahead of both my Mac.

Why?
From: Richard Maine on 14 Jul 2010 23:44
krishnananda <krishna(a)divine-life.in.invalid> wrote:

> In article <doug-C1F85B.19042914072010(a)news.astraweb.com>,
> Doug Jantzer <doug(a)gmail.com.invalid> wrote:
>
> > My iPhone is consistently 18 seconds ahead of both my Mac.
> >
> > Why?
>
> Just a guess -- your iPhone gets its time from AT&T, and your Macs
> probably use the Apple Time Server. Why there would be that much
> difference I don't know.

Me neither, but I recall a lot bigger consistent time differences that
that in other contexts. Before I retired, I was in a carpool whose
members tended to work a bit longer than the official quitting time
(yes, there are government employees like that, in this case NASA ones).
So we would often call up each other to say when we were heading out to
the car.

Fairly often, I'd have been working out of my office and get back maybe
15 minutes after formal quitting time to find a phone message saying
that another carpool member was heading out. I'd want to know whether
the message came in 10 minutes earlier, in which case I really ought to
speed out there so that they didn't wait too long on me, or whether I
just barely missed the call, in which case I could afford to take a
minute or two to clean up. But darned if the phone system didn't often
tell me that the message had come at a time that was still 10 minutes in
the future (according to clocks that I was confident in to about a
second, or at least close to that).

--
Richard Maine | Good judgment comes from experience;
email: last name at domain . net | experience comes from bad judgment.
domain: summertriangle | -- Mark Twain
From: DevilsPGD on 15 Jul 2010 02:16
In message
<krishna-CF2F11.22194314072010(a)reserved-multicast-range-NOT-delegated.example.com>
krishnananda <krishna(a)divine-life.in.invalid> was claimed to have wrote:

>Just a guess -- your iPhone gets its time from AT&T, and your Macs
>probably use the Apple Time Server. Why there would be that much
>difference I don't know.

Does anyone know where the iPhone gets it's time?

It seems to be capable of getting time without a cellular connection,
but also without any data connection, so it makes me suspect that the
phone can obtain time from NTP and/or the cellular network, but I'm
curious if it's actually documented anywhere.

The reason I'm curious, once in a while my iPhone's clock jumps about 10
minutes off. I can't narrow it down, it's not using my network's NTP
server (supplied by DHCP), but none of my other phones (that do pull
time from the same cellular network) manage to drift.
From: Fred Moore on 15 Jul 2010 10:49
In article <1jlmzul.1qkwxon9pg0cgN%nospam(a)see.signature>,
nospam(a)see.signature (Richard Maine) wrote:

> krishnananda <krishna(a)divine-life.in.invalid> wrote:
>
> > In article <doug-C1F85B.19042914072010(a)news.astraweb.com>,
> > Doug Jantzer <doug(a)gmail.com.invalid> wrote:
> >
> > > My iPhone is consistently 18 seconds ahead of both my Mac.
> > >
> > > Why?
> >
> > Just a guess -- your iPhone gets its time from AT&T, and your Macs
> > probably use the Apple Time Server. Why there would be that much
> > difference I don't know.
>
> Me neither, but I recall a lot bigger consistent time differences that
> that in other contexts. Before I retired, I was in a carpool whose
> members tended to work a bit longer than the official quitting time
> (yes, there are government employees like that, in this case NASA ones).
> So we would often call up each other to say when we were heading out to
> the car.
>
> Fairly often, I'd have been working out of my office and get back maybe
> 15 minutes after formal quitting time to find a phone message saying
> that another carpool member was heading out. I'd want to know whether
> the message came in 10 minutes earlier, in which case I really ought to
> speed out there so that they didn't wait too long on me, or whether I
> just barely missed the call, in which case I could afford to take a
> minute or two to clean up. But darned if the phone system didn't often
> tell me that the message had come at a time that was still 10 minutes in
> the future (according to clocks that I was confident in to about a
> second, or at least close to that).

Sounds like another one of those NASA units screw ups. The phone system
was using English seconds while the launch countdown was using metric
seconds. Now if you guys had just standardized on UTC seconds, there
wouldn't have been any problem. That's what you get for using the lowest
bidder. ;)
From: Thomas R. Kettler on 15 Jul 2010 13:33
In article <fmoore-9368CC.10493715072010(a)news.eternal-september.org>,
Fred Moore <fmoore(a)gcfn.org> wrote:

> In article <1jlmzul.1qkwxon9pg0cgN%nospam(a)see.signature>,
> nospam(a)see.signature (Richard Maine) wrote:
>
> > krishnananda <krishna(a)divine-life.in.invalid> wrote:
> >
> > > In article <doug-C1F85B.19042914072010(a)news.astraweb.com>,
> > > Doug Jantzer <doug(a)gmail.com.invalid> wrote:
> > >
> > > > My iPhone is consistently 18 seconds ahead of both my Mac.
> > > >
> > > > Why?
> > >
> > > Just a guess -- your iPhone gets its time from AT&T, and your Macs
> > > probably use the Apple Time Server. Why there would be that much
> > > difference I don't know.
> >
> > Me neither, but I recall a lot bigger consistent time differences that
> > that in other contexts. Before I retired, I was in a carpool whose
> > members tended to work a bit longer than the official quitting time
> > (yes, there are government employees like that, in this case NASA ones).
> > So we would often call up each other to say when we were heading out to
> > the car.
> >
> > Fairly often, I'd have been working out of my office and get back maybe
> > 15 minutes after formal quitting time to find a phone message saying
> > that another carpool member was heading out. I'd want to know whether
> > the message came in 10 minutes earlier, in which case I really ought to
> > speed out there so that they didn't wait too long on me, or whether I
> > just barely missed the call, in which case I could afford to take a
> > minute or two to clean up. But darned if the phone system didn't often
> > tell me that the message had come at a time that was still 10 minutes in
> > the future (according to clocks that I was confident in to about a
> > second, or at least close to that).
>
> Sounds like another one of those NASA units screw ups. The phone system
> was using English seconds while the launch countdown was using metric
> seconds. Now if you guys had just standardized on UTC seconds, there
> wouldn't have been any problem. That's what you get for using the lowest
> bidder. ;)

You're wrong. The 10 minute difference was due to relativistic effects
since everyone knows that moving clocks run slow.
--
Remove blown from email address to reply.
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