[ntp:questions] NTPD can take 10 hours to achieve stability

David Lord snews at lordynet.org
Tue Apr 19 14:04:09 UTC 2011


C BlacK wrote:
> I am talking about the cheep crystal oscillator in the local x86 computer.
> 

There are designs for temperature control of the motherboard
xtal and alternative of using an external 14.31818 MHz clock
source. Some of my motherboards even have an external source
connector.

I tried an experiment with a watch xtal divided down to give
a pps output with best result drift of only a few ms/day but
worst was more than 1s/day. The module was in the open but
shielded from direct sun.

There is another method where motherboard/xtal temperature is
measured and a correction applied via a patched ntpd.

Sorry but the links I have are no longer working as sites
have moved.


David

> Chip
> On 04/18/2011 05:54 PM, C BlacK wrote:
>> On 04/17/2011 10:58 PM, C BlacK wrote:
>>> Why would it take ntpd ten hours to achieve its accuracy?  Can this be explained in laymans terms and
>>> mathematically
>>>
>>>
>>>
>>>>> Absolutely normal!  NTPD can sometimes need up to ten hours to achieve 
>>>>> the accuracy it is capable of.
>>>>>
>> Thanks for all the great answers.  Now for a harder question, how does the accuracy of the local clock source
>> affect the accuracy of ntpd.
>>
>> Thanks
>>
>>
>> Chip
> 




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