[time-nuts] Discipline an oscillator with NTP?

Bob Camp lists at rtty.us
Sun Jul 24 13:15:50 UTC 2011


Hi

The standard NTP software does a "best of the bunch" selection when given a large number of servers. What it considers best and what you would pick likely are not the same thing. You stick at a few ms of error rather than getting say a 10X improvement with 100 servers.

Custom code, custom hardware, stable routing - you can do *much* better. Of the three, routing is normally the biggest source of error. If it's not you have a very unusual ISP / connection / server.

Bob



On Jul 24, 2011, at 12:50 AM, "David J Taylor" <david-taylor at blueyonder.co.uk> wrote:

>> Indeed thats why I was saying choose 3 servers.
>> Now I see in the thread that you can pick pools of servers so thats good.
>> Then average what they say the time is and drive oscillator.
>> Wonder if you could look towards the stratum 1 servers.
>> But that said I could easily believe that it might ot be any better then
>> wwv.
>> Good thread. Things to learn as we all seek a backup to GPS I assume.
>> Regards
>> Paul
>> WB8TSL
> 
> Paul, be aware that three servers is not the best choice, as if one fails you are left with two servers, and you don't know which is correct.  IIRC four, five and seven servers allow for the failure of 1, 2 or 3 of them, but do choose more than three.
> 
> 73,
> David
> GM8ARV 
> 
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