Re: [gpsd-users] ntpd vs Venus638FLPx-L with week rollover bug

[Gary E. Miller]

Yo Jeff!

On Tue, 4 Jun 2019 14:14:34 -0500
Jeff Epler <address@hidden> wrote:

> Recently I decided to add PPS time synchronization to a Rasberry Pi,
> and a Venus638FLPx-L on a SparkFun breakout board emerged from the
> junkpile.  Sadly, I discovered that this device suffers from a bug and
> doesn't report the correct time since the GPS rollover earlier this
> year.

A common tale.

> Its NMEA sentences report a date in November 1999, with two-digit
> years: 101899. It appears that GPSD interprets the date as in the year
> 2099, giving a unix timestamp of around 4'096'000'000.  Of course,
> this is too big for a 32-bit signed integer, so it ends up being
> treated as -199'000'000 seconds somewhere along the line, and so gpsd
> concludes the date is 19630912.

Which version of gpsd?  This may be dealt with in git head.

You can see your version this way: gpsd -V

> Is there (A) any knob I can turn in gpsd to work around this device's
> bugs and make it useful?

Nope.  Nor should there be a need with git head.  But that would
need to be confirmed.

There are also unconfirmed reports that simply recompiling older version
of gpsd may also work for you.

>  Failing that, (B) is there anybody who would
> like this board, if only for the curiosity factor?  It's one of these,
> which I purchased in 2010:
> https://www.sparkfun.com/products/retired/9133

A lot has happened with GPS since 2010.  So not worth much.

> In the meantime, I found a different module and got my NTP synced up
> to its PPS.

Good.

If you could provide a 30 second snippet of your NMEA, and send it
here, then someone can check if the bug is compensated for in git head.

Easy to get a capture:  gpspipe -R -n 300 > raw.log



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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    "If you can’t measure it, you can’t improve it." - Lord Kelvin

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