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Re: gpsd hardware with RTK support?
From: |
Gary E. Miller |
Subject: |
Re: gpsd hardware with RTK support? |
Date: |
Mon, 21 Nov 2022 16:34:32 -0800 |
Yo Greg!
On Mon, 21 Nov 2022 19:28:21 -0500
Greg Troxel <gdt@lexort.com> wrote:
> "Gary E. Miller" <gem@rellim.com> writes:
>
> >> MaCORS can send on various mountpoints (for carrier phase, omitting
> >> CMR):
> >>
> >> RTCM 3.x (Extended) : GPS/GLO only
> >> RTCM 3.x (MSM4) : GPS/GLO/GAL/BDS including GPS L5
> >
> > Only MSM4? Sad.
>
> I have not found info that really makes the case that MSM7 is better
> in practice.
To quote the standard that I obviously do not have a pirate copy of:
"Messages MSM1 – MSM5 are standard precision messages and messages
MSM6 and MSM7 are high precision messages. "
>
> >> I am using MaCORS which is
> >> Leica and I go into FIX very easily (given good sky view) and have
> >> observed 4 cm repeatability when occupying the same mark days
> >> later.
> >
> > 4cm not that great these days.
>
> For F9P, $100-class antenna and RTK where the reference receivers are
> in the 25 km range, vs 500m, I think it is. People quote theoretical
> accuracies all the time, and I'm talking about actually making repeat
> measurements on a real mark with some tree cover. At this degree of
> accuracy you need to be careful about leveling; I was hand-holding a
> prism pole with a bubble level.
Good for your application, but not as good as it can get.
> I would be very interested to see similar data from others, doing:
>
> establish some point that you can return to
>
> measure it with RTK (and a prism pole or tripod) once, with a 30s
> average, and compute the mean with qgis etc.
>
> several days later, do it again, wait a few more days, do it a third
> time
>
> talk about the extreme spread of the 3 measurements, longest side of
> the triangle. Explain the RTK reference source, leveling method,
> and antenna.
Maybe after the next release.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
gem@rellim.com 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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