[ntp:questions] Can NTP sync within 1ms

Rob nomail at example.com
Tue Apr 29 16:26:09 UTC 2014


William Unruh <unruh at invalid.ca> wrote:
> On 2014-04-29, Rob <nomail at example.com> wrote:
>> William Unruh <unruh at invalid.ca> wrote:
>>> The problem is not the electronics, it is the response of the system to
>>> the interrupt. That interrupt processing time is in the usec range.
>>
>> This does not really matter when it is constant.
>> And my experience is that the jitter on the PPS refclock is usually
>> 0, 1 or 2us when I check it.
>
> That sounds like 100% variability. And the serial port level converter
> time delay is much more constant. 
> Also look at the jitter when the system is heavily loaded with disk
> input/output or network load. 

This is included in the above figure.



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