NTP

[Amos Shapira]

Doesn't make sense to me:

1. The NTP server only needs the time signal, not the location (which
requires 4 satellites to be accurate), so even a signal from a single
satellite should be sufficient.
2. "getting a signal lock" is mostly a matter of having an up to date
satellite position almanac and recent location (within hundreds of
kilometers) in order to find the 4 required satellites. Finding the first
satellite is usually very quick.
3. Once the phone knows where it is, it's capable of keeping track of a car
moving at over 100 km/h for hours in order to update Google Maps and
friends. So the "keeping up" part is a solved problem, even if it was an
issue for the context of this thread.

Besides - the information should be there (the accurate time is a crucial
part of the positioning process). The main question from where I stand now
is how does Android provide access to the information (which API and was it
added to the multitude of reference clocks that the standard NTP software
comes with).

--Amos



On 8 May 2014 15:20, E.S. Rosenberg <esr+linux-il at g.jct.ac.il> wrote:

> One possible explanation may be that due to the very hard time cellphones
> have to get and maintain GPS locks (which is the reason we have
> technologies like AGPS) makes it impractical....
>
>
> 2014-05-08 14:43 GMT+03:00 Amos Shapira <amos.shapira at gmail.com>:
>
>>  I posted a question in
>> http://android.stackexchange.com/questions/68996/using-android-gps-as-ntp-refclock
>>
>>
>> On 8 May 2014 10:56, geoffrey mendelson <geoffreymendelson at gmail.com>wrote:
>>
>>> On 5/8/2014 10:49 AM, Amos Shapira wrote:
>>>
>>>> Yeah I'm with you about taking advantage of the phone's GPS signal to
>>>> get a good clock, and I thought that this is what this time-server thing
>>>> does. What does it do if not that?
>>>>
>>>
>>> The one I saw was just an Android port of the standard NTP server, which
>>> syncs to other NTP servers.
>>>
>>>
>>>> It's weird that nothing does it yet. Any takers?
>>>>
>>>>
>>> My opinion too.
>>>
>>> I'd settle for an RS232 serial emulation over USB of the old GPSs. :-)
>>>
>>>
>>> Geoff.
>>>
>>> --
>>> Geoffrey S. Mendelson 4X1GM/N3OWJ
>>> Jerusalem Israel.
>>>
>>>
>>
>>
>> --
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>> <http://www.linkedin.com/in/gliderflyer>
>>
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>


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