[ntp:questions] Jitter versus polling interval

Unruh unruh-spam at physics.ubc.ca
Sun Mar 1 21:45:57 UTC 2009

"David J Taylor" <david-taylor at blueyonder.neither-this-bit.nor-this.co.uk> writes:

>Unruh wrote:
>> YOu have a couple of answers, both of which are probably wrong and are
>> asking which it is. As stated your premise is bad. It depends is the
>> best
>> answer you are going to get. It depends on the source of the jitter.
>> Measurement noise? clock drift noise? assymetric network delays? Day
>> of
>> week? phase of moon?..... All make a difference.

>The noise I see on a typical system - typical Internet connections with no 
>local precision reference.

Ethernet (fibre, Cat5e, Gigabit switches, 1.100 switches), ADSL, modem, ...? 

Busy time of day, nighttime, backup time,...

Summer, winter, airconditioned, heated,...

>> And it depends on how it is compensated. Mill's Markovian feedback?
>> Chrony's linear regression? ...

>Regular, official NTP.  I don't run chrony.

All I am saying is "it depends".


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