[time-nuts] Smart Phone time display accuracy...?
hoag at hiwaay.net
Sun Mar 19 04:30:11 EDT 2017
Look at the line below the live time display. The data elements are the AM/PM indicator, a colored dot indicating the quality of the phone's time vs NTP time, the local time zone, followed by the offset. It's explained on the instructions that come up when you click the info button in the lower right corner of the screen.
Sent from my iPhone
> On Mar 18, 2017, at 16:43, Jeremy Nichols <jn6wfo at gmail.com> wrote:
> I have that app but don't see an option to display "the offset between NTP time and the device's internal clock." Please guide me.
>> On 3/18/2017 9:37 AM, Glen Hoag wrote:
>> On my iPhone, I run an NTP client, Emerald Time, that displays the offset between NTP time and the device's internal clock.
>> I'm on T-Mobile US and the offset is typically in the low tens of milliseconds or better.
>> It's certainly accurate enough as a clock where all I'm looking at is one minute resolution.
>> Glen Hoag
>> hoag at hiwaay.net
>> Sent from my iPhone
>>> On Mar 18, 2017, at 09:52, John Hawkinson <jhawk at MIT.EDU> wrote:
>>> Chris Albertson <albertson.chris at gmail.com> wrote on Fri, 17 Mar 2017
>>> at 14:38:17 -0700 in <CABbxVHsRa41HoB=xu4nk4T_c39uh2BCOMu17Nb7H3rA8uHXLQg at mail.gmail.com>:
>>>>> AndroiTS GPS Test (V 1.48 Free) is good, but a battery hog I find. On
>>>> THIS is why the phones don't really track time so well. Not that they
>>>> can't but doing so requires battery power.
>>> This statement doesn't seem to be well-supported. I think it's
>>> basically untrue if we're talking about timing at the tens of
>>> millisecond level. Anything more precise seems relatively useless in
>>> a smartphone without specialized mechanisms to get the time off of the
>>> A phone's GPS receiver takes a lot of battery. But GPS is not the primary
>>> mechanism that phones use get their time.
>>> They get time from the cellular phone network (whether from the layer
>>> two timing information or at a higher layer with something like
>>> NTP). The effort required to keep a phone's clock in sync, even with a
>>> really bad local oscillator, is lost in the noise of all the other
>>> things the phone has to do. It's just not a battery issue.
>>> The only reason modern smartphones keep bad time is because their
>>> designers can't be bothered to do better, or possibly the network is
>>> providing "bad" time to the phone. (Unless I'm missing something.)
>>> --jhawk at mit.edu
>>> John Hawkinson
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