Questions tagged [gps]
The gps tag has no usage guidance.
19
questions
0
votes
1
answer
270
views
Do NTP pool servers use gpsd?
A bug in gpsd upon which some NTP servers rely, has been known for a couple of months, but it hasn't really become general knowledge until recently, just before the October 24, 2021 rollover that ...
2
votes
0
answers
782
views
Local GPS clock is marked as falseticker by ntpd — why?
I have a Linux NTP server with a ublox M8Q GPS module connected via GPIO (UART @ 9600bps and PPS).
What I observe is that the local GPS source — SHM(0) — gets marked as falseticker and I'd like to ...
0
votes
0
answers
169
views
querying data from NTP in ubuntu using socket
I have configured ntp to use gpsd as reference server on my machine. I am querying data from ntp directly, using udp socket. For ip address I use localhost and port_number = 123. Packet structure I ...
6
votes
1
answer
641
views
Using GPS as only source for NTP daemon
I have questions regarding the use of a GPS receiver as an external clock source for realization of a time server with NTP daemon (client version 3), on a local network with no connection to external ...
3
votes
1
answer
768
views
are ntp.org pools and time.windows.com safe from gps 2019 week rollover?
Can anyone point to any public doc stating that pools from ntp.org and time.windows.com are safe from next thrusday gps week rollover ?
I am looking to something similar to this Red Hat KB
https://...
1
vote
0
answers
353
views
NTP does not update until after I poll it
I have NTP setup to run with GPSd and all is well. The issue arises after about a week of my raspberry pi being disconnected, NTP will trust the old date on the system clock. Since the GPS takes a ...
1
vote
0
answers
22
views
Changing Polling times on a VM running under Server2012 R2?
Is there a way to know or change the polling times of VMs running under a Hyper-V 2012 R2 server? We have set all the hosts and physical domain controllers to keep time with our new GPS time server ...
-4
votes
1
answer
473
views
Ping latency vs location on a map (x kilometer of a trip) | ping-latency vs distance
Orange is having problem delivering the internet between biggest cities (I'm traveling via train). There are white spots on the way...
They do not see the problem, so I thought - lets make a chart
...
1
vote
1
answer
5k
views
chrony and gpsd: socket or PPS connection
I've try to get high precision time from gps receiver GlobalSat BU-353s4 (/dev/ttyUSB0) through gpsd in Raspberry PI with ArchLinux.
/etc/chrony.conf contains:
refclock SHM 0 delay 0.5 refid NEMA
...
4
votes
1
answer
1k
views
Is PTP really more precise than NTP? If so, why?
I have read quite a bit about NTP and PTP time keeping protocols. While many sources claim that PTP is more precise than NTP for that type of granularity - the reason is not as clear. Why can't NTP be ...
1
vote
2
answers
3k
views
Setting ntp time from gpsd
I'm trying to configure ntpd to source it's time from a gps receiver (BU-353S4) but I'm getting some errors.
I'm using ntpd 4.2.8.p6-3 and gpsd 3.16-2 on Arch Linux Arm. I've been following the ...
8
votes
2
answers
2k
views
Getting gpsd address for ntpd
I'm working through some tutorials for setting ntpd clock from gpsd. The guides that I'm working from list adding something like this:
server 127.127.46.0
fudge 127.127.46.0 time1 0.0 time2 0.0 ...
3
votes
1
answer
3k
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 ...
10
votes
1
answer
601
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 ...
3
votes
2
answers
4k
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
1
answer
2k
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
1
answer
3k
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", RUN+="/bin/...
8
votes
3
answers
12k
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 ...
37
votes
12
answers
22k
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. ...