Re: GPS/PPM very large offset

[Gary E. Miller]

Yo B&A!

On Fri, 6 Nov 2020 15:42:22 +0100
B&A Consultants <infos+gpsd@ba-consultants.fr> wrote:

> We are using an Uputronics GPS board on a pi2 with Gentoo Linux. The
> Pi2 has no other function than delivering time to our machines. It
> has been working ok for some time, and NTP did use the GPS/PPS
> sources to get the time.

We need some of you implementation details to take a guess here:
        gpsd version
        gpsd command line
        ntp.conf

Does cgps show a valid 2d fix?  For how long?
How many leap seconds does cgps show?

> Not anymore, those two sources are considered invalid : they exhibit
> a *5 seconds* offset :

The good news is that it appears to be exactly 5 seconds, so unlikely
network related.

> Is such a huge offset « usual » ?

Common when the GPS does not have the current leap ssecond yet.

> What could it mean (hardware failure ?).

Some older firmware can compute the leap wrong.
Also it takes a while, up to 30 min, to get the leap second on startup.

> The Gps gets proper fixes, as per cgps (do not know if
> it's okay to attach a screen copy, will do if requested).

cgps is just text, so you can cut/paste that here.  SCreen shots are
often hard to read and impossible to cut/paste.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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