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Re: ntrip and sending position

From: Gary E. Miller
Subject: Re: ntrip and sending position
Date: Wed, 18 Dec 2019 15:50:36 -0800

Yo Greg!

On Wed, 18 Dec 2019 17:32:38 -0500
Greg Troxel <address@hidden> wrote:

> "Gary E. Miller" <address@hidden> writes:
> >> I find that WAAS isn't as good as local DGPS from the USCG used to
> >> be, even with a clear sky view.  But I have no hard data.  
> >
> > Of course.  Local corrections are better than wide are corrections.
> > But some GNSS receivers consider them equal when turning on DGPS
> > status bit.  
> Agreed that they both count as DGPS.  I just meant that I suspect that
> between local and rate that the local ones are better.


> >> I have the impression PPP requires static observations for a
> >> longish time, vs being able to produce a gpx of a moving receiver.
> >>  
> >
> > 10 to 15 mins is considered the minimum.  Getting better up to about
> > 24 hours of data.  There are services that will post process moving
> > data, at less precision.  That is essentially the same as RTK.  
> And it probably needs the same kind of not having cycle slips as RTK.

Cycle slips happen.  To avoid them you need to move really slowly.
Even a fast walk can be too fast.  Even stationary I get them as
sats cycle through the used list.

> > All GNSS receivers do better with better sky views and better
> > signals.  
> Sure.  I meant that RTK doesn't really work at all without good views.

No GNSS receiver works without good views.

> > No reason your base should not have a great sky view and signals.  
> My base is run by MassDOT, and has Leica stuff that I'm sure is very
> spiffy.  So I expect high-end performance on that side of things.

Such were my expectations of ORGN.  The results, not so much.

> > I don't see much improvement with expnsive equipment over a
> > ZED-M9P.  
> I had some offlist conversations with a Trimble emploeyee, who claims
> that their stuff can do RTK with tree cover, and sent me imagery
> where I can't see the ground.

I've rarely had problems with trees.

>  If you are succeeding at < 10cm RTK
> with a ZED-M9P and some antenna under tree cover -- or even if in the
> open -- please post part numbers and I may try it out.

I was getting 1cm years ago with Skytraq and RTK.  Never tried with
trees.  I do not have even one of thee two ZED-M9P I'd need to test.

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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