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Re: [gpsd-users] Garmin 18X LVC and upcoming week rollover

From: Gary E. Miller
Subject: Re: [gpsd-users] Garmin 18X LVC and upcoming week rollover
Date: Mon, 18 Feb 2019 16:59:20 -0800

Yo Rich!

On Mon, 18 Feb 2019 14:45:46 -0800
Rich Wales <address@hidden> wrote:

> > /3.15? Really? Fix that./  
> Thanks.  I have.  3.17 now.

3.18.1 is current.  There are some CVE in 3.17, so watch your host
until you get 3.18.1

> > /You, and everyone else, wants to know the answer to that. The
> > Garmin firmware is proprietary, and unsupported. OTOH, that is an
> > ancient GPS. Modern GPS are much better. Skip the worries, and get
> > 10 years of bug fixes by spending $20 on a modern one./  
> Thanks.  I'm going to wait until April and see what happens then.  I
> imagine the rollover code in timebase.c may rescue me; if not, I'll go
> looking for a new GPS unit at that time.

As long as you don't do anything critical on roll-over date.  But
almost as likely there is a different roll over data bakend into your

> I've had 9+ years of solidly reliable performance from this Garmin 18X
> LVC, but I realize no hardware lasts forever.

For its time, it was great.  You will see much better performance with
a newer model.

>  If I were to replace it
> now with a newer GPS unit, what specific modern models should I look
> at?

Well, that depends on what your needs are.

>  My existing unit -- a miniature "hockey puck" with a pigtail of
> bare wires -- is connected to a DB9 serial connector (plugged in to an
> RS232 serial port on my desktop computer), with a separate USB
> connector solely for supplying power.

I have something similar on my 18x.  Problem is that it will not
work inside, like newer GPS.

>  I am intentionally not using a
> USB data interface to the GPS unit, btw, in order to avoid known
> latency issues with USB serial adapters.

Yup.  You turn a 1 us GPS in to a 2 ms GPS that way.

>  The GPS is being used
> exclusively for time sync via GPSD and NTPSEC, so I have no need for
> any fancy box, display, or the like.

RS-232 is getting harder to find.  If you need that, your choices narrow,
or you need a TTL to USB adapter.  That adds a few dollars and some
hacking.  Or just go to a Raspberry Pi and use a 3.3V or 5V GPS.

You can get some u-blox 6 with RS-232 for about $20:

But a u-blox 8 will be more sensitive.  $40 will get you one of those:

Keep an eye on e-bay and you'll see good deals come and go.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  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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