Re: [gpsd-dev] gpsd rolls back to 1999

[Gary E. Miller]

Yo Sanjeev!

On Sat, 22 Jun 2019 10:49:30 +0800
Sanjeev Gupta <address@hidden> wrote:

> I have a Surefire MTK-3301 , which has been running well for over 6
> years. Noticed today that ntp was reporting 1999 .

This is bascially this issue:

    https://gitlab.com/gpsd/gpsd/issues/3

You got hit by the GPS Week Rollver (GWRO) bug.  That happened to you,
and others, on April 6th, 2019.

Not to be confused with this month's Leap Second Roll Over bug.

Your GPS is reporting that it is 1999:

$GPZDA,023522.000,06,11,1999,,*5C
                        ^^^^
And not only the year.  The month and day as well:

$GPRMC,023523.000,A,0118.6185,N,10345.1253,E,0.00,328.56,061199,,,D*66
                                                         ^^^^^^

You took your sample on 22 June 2019, but your GPS reports 11 June 1999.

Dunno if your time of day is correct.  The date time matches the
$GPRMC time, but that is expected since you set your system clock
from your GPS?

If it was just the year, the fix might be easy, but there needs
to be some fancy date math too.  Not gonna happen for 3.19.

You GPS seems semi-sane, but there are reports of all sorts of
craziness due to the GWRO.  Sometimes 1963, 2099, etc..

I assume your ntpd is rejecting that as a false ticker?

As a stratum 1 server, gpsd has to trust the GPS.  I guess we could
just reject any date before the compile date, except that breaks the
regressions.

Why not spend $15 and get a modern GPS?

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

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