On 2010-02-22, ryandoyle <[email protected]> wrote: > For anyone interested in setting up a Garmin 18 LVC GPS receiver on > FreeBSD 8, I wrote up a fairly detailed tutorial of my experiences > here: http://blog.doylenet.net/?p=145 > > A couple of months ago I thought it would be a neat idea to run a > strat 1 time server at my work. I hadn't had any experience with NTP > before, didn't know what local clock drivers were etc... and coming > from a Linux background I had very little experience with FreeBSD.
I disagree with your comments re the accuracy on Linux. I have consistantly gotten 2usec accuracy on Linux with ntpd, (and with chrony, Lichvar gets sub usec accuracy with no change in the kernel). The important thing is to get the time into the system as rapidly as possible from an interupt. I wrote my own interrupt driver for the parallel port to get the data in as quickly as possible, and running tests ( Tie an output data line to the parallel interrupt line, time when you output on the data line, time when you get the input from the interrupt) I get about 1-2usec delay on the interrupt on Linux spread between output and input. With ntp, the other problem is that the algorithm used responds very slowly to temp changes. This is the primary limit to the accuracy of an ntpd driven refclock. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
