On 13 Jan 2016 at 14:20, David Rawling wrote: > I'm thinking of getting back into proper timekeeping now that I have my own > place and can (finally) put up a GPS antenna for my poor unloved timeserver. > ..... > Any tips / pointers to guides much appreciated >
Hi I added two ntp servers to the pool late 2009 then in 2011 most of my network was badly damaged by a mains electrical fault. When I had repaired some of the damaged pcs I eventually had four internet servers in the pool. Since around 2010 I've had a GPS as source, first was a Garmin 18X-LVC then a Sure. They were connected to serial or parallel ports on a pc running NetBSD. My monitoring didn't show any significant differences between Garmin or Sure, nor between serial or parallel. On more recent hardware I'd expect GPIO to be usable in place of serial/parallel. Daily rms offsets (us) over 31d to 2015-12-24: pc hostname #1 #15 #29 d525mw01 mail0 111.3 163.6 230.2 d525mw02 mail 47.5 94.5 134.6 d525mw03 117.7 149.2 195.1 e350n1b 869.0 2702.7 12157.3 me6000e 3.6 4.0 6.5 me6000g ns2 152.9 243.4 328.3 p3x1300 113.6 131.9 237.4 pd6000e2 ns3 74.1 108.3 149.4 Offsets are mostly below 300us except for one amd64 pc, e350n1b, that has an out of tolerance xtal causing offset to sometimes be above 20ms. Offset of pc with PPS from a GPS, me6000e, is mostly below 10us. Without stable local or external system clock sources, offset of any of above pcs can vary significantly when under load and/or subject to large ambient temperature changes. I intend to assemble an OCXO for use as external system clocks which with PPS should give stable offsets below 300ns. Bad news is that this requires solder connections to each motherboard. An alternative is to fit temperature controlled heaters to xtals on the motherboards. David -- David Lord <[email protected]> <ftp://ftp.lordynet.org/pub/pgpkeys/[email protected]> <http://www.lordynet.org/pub/pgpkeys/[email protected]> _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
