Re: [questions] Re: GPS+PPS vs NTP server, why a huge offset ?

Quoting Daniel O'Connor : If you are using it for NTP then GPS+PPS over USB is quite adequate (from personal experience). Ian Lepore (RIP) who worked for Micro Semi and worked on FreeBSD did a bunch of tests on a PPS over USB setup and found it more than acceptable for keeping a PC in

Re: [ntp:questions] Realistic Performance Expectation for GPS PPS fed ntpd jitter

Quoting Andreas Mattheiss : I wonder what's a realistic ballpark for the jitter I can expect when feeding a GPS PPS into ntpd? Assuming Linux, and using pps-ldisc or pps-gpio, I'd expect reported jitter to be around 1us : The jitter values I get do, sorry, jitter. I guess it's a lot to do

Re: [ntp:questions] Performance estimation

Quoting David Taylor: The clock on a Raspberry Pi ranges from 700 to 1500 MHz, so clock resolution is in the nanosecond range. There is mention of 250 MHz as well, which would be 4 nanoseconds. It would be nice to see numbers which distinguish a little better than earlier RPi is "3" and more

Re: [ntp:questions] help with setting up NTP on windows with a USB GPS

On 07/30/19 03:48, Jakob Bohm wrote: USB-to-RS-232 converters generally completely loose the precision timing abilities of traditional serial port circuits (a 16550 or equivalent chip connected to the main CPU bus like in the serial adapters for the original 1981 IBM PC). This is because the

Re: [ntp:questions] Garmin LVC 18x jitter problem

Quoting David Taylor : I'm not an expert in this, but the timing seems to be the same in both graphs, the problem occurring around 8000. Could that be due to someone with a GPS jammer parking nearby? To expand on this: what were your GPS satellite signal strengths like during this time

Re: [ntp:questions] NTP using server IPV6 address instead of IPV4

Quoting "Potter, Timothy CCS" : I have a laptop running a version of Linux ( 3.12 ). I have ntpd installed and configured to sync with time.google.com. The problem I am having is if I am plugged into a network that only provides an IPV4 address, ntp's dns is using the ipv6

Re: [ntp:questions] Long term disciplining against 1PPS reference only

Quoting "Charbonneau, André" : Recently I've been trying to get one of my NTP server (a Raspberry Pi), to stay synchronized to a 1PPS signal coming from a Rb clock over long periods of time when all other sources are unavailable. The NTP server on the RPi is configured to have a couple

Re: [ntp:questions] Time syncing with something other than ntpd

Quoting Jakob Bohm : 1. Do you know if anyone has tried using the real-time coprocessors on the BBB to more accurately track the PPS signal? I have a driver for the BBB's input capture timer hardware here: https://github.com/ddrown/pps-gmtimer There's a bug in the

Re: [ntp:questions] Atheros AR9331 w/GPS + PPS

Quoting Gabs Ricalde : ... You can also improve the stability of the local clock by avoiding rapid temperature changes. This is the loopstats of a TL-WR841N placed inside a box where the temperature doesn't change that fast. https://imgur.com/a/eNT0k Rapid temperature

Re: [ntp:questions] Atheros AR9331 w/GPS + PPS

Quoting Joachim Fabini : : I'm really surprised, that's excellent. Do you have any figures how ntpd performs when using this PPS source? My earlier comment was relying on the assumption that the diagram displays the ntp log (loopstats) statistics. Until now, with

Re: [ntp:questions] measuring os latency for pps

Quoting folkert folk...@vanheusden.com: Not sure if it is interesting for you guys but I wrote a simple program for e.g. Linux (or any other system with the pps api implemented) that listens on a pps source waiting for a pulse and then toggles a gpio pin. That way you can measure the latency