Setting the time on the watch

Discussion in 'Apple Watch' started by ianrip, Apr 26, 2015.

  1. ianrip macrumors 6502

    ianrip

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    work:Oyu Tolgio, Home:LOS, From Scotland G15
    #1
    Is the watch and the iphone in sync???

    or will the alarms go off at different times etc.

    I disable the “Set Automatically” on my iphone to conserve battery power, can we do the same with the watch ????
     
  2. dylman macrumors regular

    dylman

    Joined:
    Oct 30, 2014
    #2
    I don't think you can manually set the time. I'm fairly sure the watch syncs itself with Apple's servers (through the phone),so you might as well get the phone to do it as well.
    You're only saving fractions of a percent of battery, and if you're setting the time yourself regularly probably using more (screen being on uses more battery than a quick ping of a time server).
     
  3. ianrip thread starter macrumors 6502

    ianrip

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    #3
    I've only set the time once since I’ve had the iphone, I thought if its “Set Automatically” it must be looking once per day, where “manual” it doesn’t care as its asleep
     
  4. dotnet macrumors 6502a

    dotnet

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    #4
    Very good question. Until five minutes ago I would have guessed no, since the watch is known to sync using NTP and the phone gets its time from the cellular network. In other words, the watch would be more accurate than the phone.

    I've got the Chronometer app on my iPhone, which shows a range of lovely watch faces and syncs with NTP. It also shows the offset between NTP and iPhone time, but is unable to correct the iPhone system clock, because apps aren't allowed to.

    The offset between NTP and iPhone time was usually in the range from 0.1 to 0.5 seconds, so not very large at all, but still there.

    Checking (and re-checking because I couldn't believe my eyes) just now I found the offset of the iPhone clock from NTP to be much smaller than usual, between 0.00 and 0.01 seconds. Those 0.01 seconds are smaller than the Chronometer app's current NTP sync accuracy (0.03 seconds), so this leads me to believe that iOS has quietly moved to syncing off NTP servers itself, rather than off the cellular network.

    If this is true I don't know whether it is a new feature in iOS 8.3, or whether this only happens when people pair an Apple Watch with their iPhone. My iPad in comparison, running the Chronometer HD app, still shows 0.37 seconds offset between iOS and NTP. It syncs off the cellular network.

    It could well be that in order to achieve the 0.05 second accuracy advertised for the Apple Watch the paired iPhone gets upgraded to NTP time sync, because I doubt the watch itself would be making the periodic network connections to NTP servers that are required to achieve and maintain good synchronisation.

    If the iPhone turns to NTP once paired with a watch then this would also go some way to explain the hit on battery life that some people around this forum are reporting.

    I don't think setting the time automatically on an iPhone in the past did anything to conserve battery power.
     
  5. Newtons Apple macrumors P6

    Newtons Apple

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    #5
    Setting the time automatically would use so little power that it's not worth turning off. Correct time is usually provided by your carrier. Are you running out of battery power before the day is out?
     
  6. Scott6666 macrumors 65816

    Scott6666

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    Feb 2, 2008
    #6
    Ironic that on a watch one of the most non-obvious things is how to set the time.
     
  7. ianrip thread starter macrumors 6502

    ianrip

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    #7
    Sorry that's the complete opposite
     
  8. Newtons Apple macrumors P6

    Newtons Apple

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    #8
    Please educate me on why you think the watch consumes so much power to keep the correct time.
     
  9. kdarling macrumors demi-god

    kdarling

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    #9
    Interesting post. Thanks very much for checking against NTP!

    Do we know for sure the watch time is based on NTP? Or is that just a widespread assumption because of the 50ms accuracy claim, as opposed to GPS time (which is about a million times more accurate), or network time (which can be seconds off).

    Weird. Supposedly, starting with iOS 5.0, iPad-WiFi time comes from NTP. So is the cellular model worse at time because of using NITZ?

    I think you could be right. It's certainly one possibility.

    Apple will probably have to detail their chosen method(s) sooner or later, since it could be false advertising to claim such accuracy, without also specifying that it requires a phone with a data connection to work.
     
  10. dotnet macrumors 6502a

    dotnet

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    #10
    I don't think I've heard it stated by Apple, so it is an assumption, spread by some early reviewers (who may or may not have been told verbally by Apple). However, cell network time could't provide this accuracy and GPS is probably too hard on the battery (location services is a major battery hog in iPhones)

    Yes, again the answer could be battery life. The WiFi-only models don't have any other choice and can probably afford to use NTP because they don't have to power a cell radio. The cell models are compromised in that regard already and make do with cell network time, which comes at no extra cost to battery life. It would be interesting to see how badly the time on a WiFi-only iPad drifts when away from the net for a while.
     
  11. kdarling macrumors demi-god

    kdarling

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    #11
    Yeah. People have noted that iOS devices can drift up to ten seconds a day on their own (more normally within a couple of seconds), so I'm wondering if the battery hit to ensure 50ms is worth it.

    First off, what's the point of it, except perhaps to help dancing Mickies stay in sync (and it'll probably only work best for watches all the same room where every iPhone got a similar time sync). Otherwise, a user at most needs the time to the second.

    Secondly, even if the watch or phone would only normally drift one or two seconds a day, they'd have to check the time every hour or more to stay within 50ms. Ah well, I suppose that's not much of a power hit.

    Still and all, it feels like one of those specs for specs' sake, at least on a watch.
     
  12. vikingjunior macrumors 65816

    vikingjunior

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    Aug 17, 2011
    #12
    without starting a new thread can you set it to military time?
     
  13. dotnet macrumors 6502a

    dotnet

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    Apr 10, 2015
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    #13
    Yes, I found this curious, too. Normally Apple would focus on utility and user experience rather than specs, with iPhones and iPads you don't hear them talking about mega-this or giga-that (except for storage capacity, which almost everybody is able to grasp and compare). So, pointing out this 50ms figure feels as strange and unnecessary as the 300-odd dpi they paraded for the first Retina displays.

    ----------

    If you mean 24-hour time, yes.
     

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