[ntp:questions] Using Trimble TSIP under Linux

David Taylor david-taylor at blueyonder.co.uk.invalid
Tue Nov 27 08:19:47 UTC 2012


On 26/11/2012 23:59, David Woolley wrote:
> Offsets should be randomly distributed between + and - signs.  If they
> are all of one sign, you are not locked up or there is a bug.  They
> should be of s similar magnitude to the jitter.
>
> They may not be evenly distributed, because of limitations of the
> network, but they must be spread across zero.

On the card which is synced purely to LAN servers, over a day the mean 
offset of the FreeBSD stratum-1 server (the selected sync source) is 
0.000 ms, and that of two Windows stratum-1 servers is 0.014 ms.  The 
mean jitter is 0.041 ms (FreeBSD) and 0.048 and 0.280 ms (Windows).  The 
offset of WAN-based pool servers was in the region of 2 - 8 ms.

On the card with the PPS source, the mean offset of the other servers is 
-0.020 ms (FreeBSD) and -0.008 ms (both Windows).  Mean jitter is 0.230 
ms (FreeBSD) and 0.036 ms and 0.230 and 0.047 ms (Windows).  The offset 
of WAN-based pool servers was in the region of 2 - 14 ms.

THe WAN is vai a cable modem connection, rather asymmetrical at 30 Mb/s 
down and 3 Mb/s up.
-- 
Cheers,
David
Web: http://www.satsignal.eu



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