[time-nuts] ntpd not talking to gpsd

Hal Murray hmurray at megapathdsl.net
Wed Apr 2 03:13:15 EDT 2008


> server 127.127.28.0 minpoll 4 maxpoll 4

Speaking of gpsd and ntpd...

That minpoll/maxpoll stuff is trying to work around a bug/oversight in ntpd.

The current code grabs one sample per polling interval.  The right way is to 
grab a sample every second and filter/average them over a polling interval.  
ntpd had code to do all the hard work.  I've got a patch for the shared 
memory refclock driver that takes advantage of that.  Results are here:
  http://www.megapathdsl.net/~hmurray/ntp/GPS18USB-SHM-off.gif
  http://www.megapathdsl.net/~hmurray/ntp/GPS18USB-SHM-jit.gif

A long time ago, I asked on comp.protocols.time.ntp but nobody responded.

Is anybody here willing to help test it?  If so, please contact me off-list.



-- 
These are my opinions, not necessarily my employer's.  I hate spam.






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