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1
vote
1answer
36 views

NTP using GPS and PPS as clock, PPS is marked as falseticker

I am attempting to add a GPS-based clock source to my network, using a GPS which emits a 1-PPS clock pulse. This is connected to a GPIO pin. After allowing ntpd to run for 30 minutes or so, the PPS ...
9
votes
1answer
182 views

Linux ntpd leap second preparation

There will be a leap second on June 30, 2015 at 23:59:60 UTC. I have a Linux based stratum 1 NTP server which uses GPS as a reference clock. The server is using the "default" ntp.org ntpd. How ...
2
votes
1answer
742 views

configuration to use gps time with no internet connection

I use ntp with a GPS device with PPS on port /dev/ttyS0. All seems to be fine if the machine is connected to the internet. Output looks correct. But if there is no internet connection I get: $ ntpq ...
1
vote
1answer
526 views

Access NMEA reference clock and GPS position simultaneously

I noticed two approaches to get an accurate time from GPS (with PPS). Using ntpd either with NMEA reference clock or Shared Memory Driver My problem: I want to have a very accurate time and access ...
2
votes
1answer
417 views

udev rule running setserial low_latency don't work

My server runs Ubuntu 14.04.1. I created udev rules in /etc/udev/rules.d/09-pps.rules to get GPS with PPS support work. KERNEL=="ttyS0", SYMLINK+="gps0", MODE="0666" KERNEL=="ttyS0", ...
6
votes
3answers
4k views

Seemingly poor quality of NTP time synchronization using a GPS clock

I have a Linux server which has its time synchronized to a GPS-based NTP appliance located close by. Ping times from the server to the appliance are circa 1ms, with very low jitter: --- x.x.x.x ping ...
30
votes
12answers
14k views

Is anyone using GPS for time sync?

I've come across a handful of GPS NTP servers, as well as some inexpensive solutions using off-the-shelf receivers and software. Right now I'm just using NTP with a list of servers over the Internet. ...