Yes the Emlid unit is quite interesting for the price... Nicolas Cadieux https://gitlab.com/njacadieux
> Le 6 mars 2021 à 11:04, Dan <19dm...@gmail.com> a écrit : > > > Kirk is spot on. That unit is for GIS use and cannot receive RTK GNSS > corrections. You will need a survey grade receiver, with RTK corrections (or > post processed) for better accuracy. > > Budget option for cm accuracy is the Emlid Reach RS or RS2 > >> On Sat, 6 Mar 2021 at 23:53, Greg Troxel <g...@lexort.com> wrote: >> >> Springfield Harrison <stellar...@gmail.com> writes: >> >> > I recently acquired a Trimble GeoXT 2005 Series and am puzzled by the >> > results it produces: >> > >> > 1. Compared to a variety of "known" points, it consistently records >> > positions that appear to be in error by 1.2 - 1.5 m NW from the >> > known point. >> > 2. Points are collected and then mapped in QGIS as NAD83, UTM Zone 10 N. >> > 3. The known points include property survey pins, Government control >> > survey monuments, Total Station survey points derived from the >> > above, other GPS results (Trimble ProXRS) and identifiable points on >> > orthophotos. >> > 4. I'm using SBAS correction in the GeoXT. >> > >> > It appears to be adding a consistent offset to the GPS result although >> > no offset has been set in TerraSync. >> > >> > Many thanks for any thoughts on this situation . . . . . >> >> I'm really not clear on what this particular receiver is purporting to >> do, but a consistent meter-ish offset smells like an incorrect datum. >> >> If you are using SBAS and in the US, that means WAAS. So you are >> getting results that in some CRS that the list hasn't figured out what >> it is, but "ITRF2008 current epoch" is my best guess. That's >> essentially equal to "WGS84(G1762) current epoch". >> >> Those frames are definitely not equal to any flavor of NAD83. >> >> qgis, via proj, will treat "WGS84" and "NAD83" both as datum ensembles >> and because each ensemble has a low-accuracy member treat them as equal, >> and thus choose a null transform. IMHO this is the wrong thing to do, >> as WGS84(G1762) and NAD83(2011) are both datums with high intrinsic >> accuracy and are definitely not equivalent. >> >> Converting from ITRF2014 to NAD83(2011) will apply a datum shift. >> >> Advice 1 is to shift your project CRS from NAD83 to ITRF2014 and see if >> the relative position of the observations and controls changes. If so, >> you have datum transform trouble. >> >> My real advice 2 is to take the data file from the unit and label it as >> ITRF2014, and then see how things line up. If you are talking about a >> meter you need to really pay very close attention not only to datum >> labeling but also in understanding the transformations your software is >> making. >> >> Greg >> _______________________________________________ >> Qgis-user mailing list >> Qgis-user@lists.osgeo.org >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
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