[ntp:questions] Re: GPS Time source offset

Patrick Klos pklos at osmium.mv.net
Fri Oct 21 20:03:45 UTC 2005


In article <1129915741.107351.269460 at g47g2000cwa.googlegroups.com>,
DJ <drnj at freemail.redherring.co.uk> wrote:
>I have a 4000 GPB ($6000 ?) GPS time source - it works beautifully.
>I then took a $200 etrex hand-held GPS, set it to NMEA mode, plugged in
>into a serial port on a Linux machine, I then did
>ln -fs /dev/ttyS0 /dev/gps0 and configured ntp.conf
>
>server 127.127.1.0
>fudge 127.127.1.0 stratum 10
>
>server 127.127.20.0
>
>I started ntpd and then my linux platform appears as a stratum 1
>server. However, it seems to have an approx 300mS offset from the 4000
>GBP GPS time source. 

What are the chances that one or the other of your time sources is using
the wrong edge of the PPS?  300ms sounds like a reasonable "active" time
for a pulse per second signal.

================= GPS based time synchronization solutions =================
    Patrick Klos                           Email: patrick at timegeeks.com
    Klos Technologies, Inc.                Web:   http://www.timegeeks.com/
==================== http://www.loving-long-island.com/ ====================




More information about the questions mailing list