Kevin Oberman wrote: > Also, the jitter on your time is extremely high for PPS which should be > < 1 us. I suspect that this is a system problem, but I can't be sure. I > never see this much jitter on any of our PPS synced reference clocks (of > which we have about 25 scattered across the US). If the jitter on any of > my reference clocks using PPS exceeds .005, I consider this a big > problem. I use FreeBSD which has excellent PPS support.
I have setup a bunch of FreeBSD based refclocks over the years, mostly Oncore UT+ timing receivers (15-50 ns) but also Gar 18LVC as well as an Endrun CDMA-based clock in the US. I just got my homebuilt 18LVC back in operation today, after moving to a new office building: I use this the monitor all my official refclocks by configuring them as servers to my local box, so I can compare with the GPS results. Since the Garmin isn't a timing-optimized receiver, I cannot put it in Zero-D like the Oncores, and it has a less than optimal window sill location (pointing NE in Oslo, at 60N), but I'm still getting offset mostly around +/- 2-3 us, and sub-5 us jitter. Terje PS. I had lost my original documentation on how to setup a server with this GPS, but a little Googling found lots of howto, including some that quoted my old description. :-) -- - <Terje.Mathisen at tmsw.no> "almost all programming can be viewed as an exercise in caching" _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
