[ntp:questions] custom NMEA messages

Paul tik-tok at bodosom.net
Mon Jan 4 18:26:10 UTC 2016


On Mon, Jan 4, 2016 at 3:58 AM, Hal Murray <hmurray at megapathdsl.net> wrote:

> > On Tue, Dec 29, 2015 at 4:08 PM, Brian Inglis <
> Brian.Inglis at systematicsw.ab.ca> wrote:
> > If you are looking at NMEA message timing - that's all over the board on
> > every device
>
> No, some devices do it right.  Look at my graph (way above).  You can do a
> whole lot better than most devices do.
>

If you're referring to your 18 vs 18x chart then I would disagree.  The 18
numbers are typical of my experience with various NMEA serial devices.
I've found one exception -- the JL Fury.  These are typical values:

o127.127.22.0    .GPPS.           0 l    5    8  377    0.000    0.001
0.002
*127.127.20.0    .FURY.           0 l    4    8  377    0.000   -0.042
0.023

The JL Firefly II is about an order of magnitude worse than the Fury so
it's not simply that they're GPSDOs from JL.  Still better than your
typical serial device but nothing to write home about.


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