Yo Greg! On Wed, 26 Nov 2025 08:11:13 -0500 Greg Troxel <[email protected]> wrote:
> > I prefer to say the restuls are the results. They are what they
> > are. The hard foundation on which theories are built.
>
> My point is that you are saying CEP as if the mean or some such is the
> true answer. A tight cluster of positions that is 3m from the true
> position is going to have a good CEP by your analysis, but it's still
> 3m off.
Not my terms. All terms in the scatterplot are from standard RCC 261-00.
All computations are also per that standard.
But yes, similar to Hans's recent posts, getting a solid true position
is non-trivial. As I mentioned to him, a trip to a local USGS banchmark,
known to about 1cm, is on my TODO list.
> >> My take from watching that is that there are significant, perhaps
> >> dominant, periods when the device is in RTK FIX.
> >
> > I almost never see RTKFIX. I think it is dropping into simple DGPS
> > (SBAS) mode for a short period.
>
> huh. In my book, RTK without FIX is deficient.
Not ideal, but it is what it is. Nothing I can do about it.
>
> >> And, periods when FIX is lost, and it's RTK FLOAT (or maybe maybe
> >> even just autonomous/DGPS). I find that there is a slow wander to
> >> FLOAT.
> >
> > I hace not seen fix lost. I'll see if I can write a program to
> > extartc $ of time in each assist mode.
>
> That would be most enlightening.
That was in my next message.
> >> It would be interesting to process the data by looking at only
> >> points in FIX, and to plot the non-FIX points separately.
> >
> > So yeah, when I'm guiding my car with the GPS, I'll just freeze when
> > assist mode changes?
>
> I don't understand why you said that.
To be blunt, tossing out data points is just wrong.
> The first question is to
> understand what's going on, and then there's a later question about
> how useful it is.
Without access to the u-blox code, I doubt we will ever know. Since I'm
not a real "end user", they will have to speak for themselves on their
use cases.
> If it turns out that plots segregated by mode show
> that different modes have different error statistics, that's really
> useful to know.
I'm sure we already know that. We have a lot of experience with F9P, and
never have seen anything remotely close to this good before.
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
[email protected] 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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