[ntp:questions] How to debug GPS PPS?

David J Taylor david-taylor at blueyonder.delete-this-bit.and-this-part.co.uk.invalid
Thu Dec 31 07:19:01 UTC 2009

"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message 
news:FbGdnYtRs_jzfqbWnZ2dnUVZ_s-dnZ2d at giganews.com...
> Your biggest problem may be that Windows is not exactly the world's 
> greatest time keeper!  The clock "ticks" every 17 milliseconds!

Whilst this is correct and, yes, FreeBSD can do better, it may be 
misleading because with care Windows does much better than 17ms for 
running NTP.  Here is data I've gathered from my own GPS-synced Windows 

PC Feenix - offset typically better than 250 microseconds:

PC Stamsund - offset typically much better than 250 microseconds:

PC Bacchus - offset typically better than 250 microseconds, except when 
the CPU suddenly changes from 0% to 100% CPU usage for an hour, and causes 
a considerable temperature rise:


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