[I'm not sure how on-topic this is for qgis-user, but I'm guessing it's relevant enough, at least until a Moderator comment otherwise.]
Springfield Harrison <stellar...@gmail.com> writes: To figure out what's going on this description needs to be tightened up, which is probably going to require trimble documentation or support to clearer (maybe the docs are fine; I haven't looked). > For many years my work flow has been: > Trimble Receiver + RTCM/SBAS -> This is unusual phrasing. SBAS is a class of things, not a particular corrections source. I'm guessing you are in North America and this really means WAAS. RTCM is a family of protocols for transporting corrections. I am unclear on whether the WAAS format uses RTCM but I don't remember seeing it. Within RTCM there is RTCM2, usually used for pseuorange corrections, and RTCM3, usually used for carrier phase reference data. So I wonder if the ProXR is doing RTK, what the correction source is, and what the distance to the base station is (or if it's VRS). To me the most important thing to be precise about is pseudorange solutions (often called navigation solutions) vs carrier phase solutions (post processed or RTK). Then, there's PPP which is harder to understand. So I think you mean that while you were collecting points the receiver was calculating pseudorange solutions and using the pseudorange corrections delivered by WAAS. > Pathfinder Office [+ RINEX Post Processing] -> SHP files -> GIS (QGIS > or Manifold GIS). You say "RINEX Post Processing" but that leaves out a ton of important details. I am guessing you mean that the receiver records carrier phase observables, and then there was a double-differenced carrier phase solution for each ooccupation. The obvious question is where the reference station data is coming from, how far away it is (or is it some VRS), and what datum the reference station coordiantes are in. Or maybe this is doing PPP. There, similar questions apply about where the orbit data is coming from and what frame that is in. > The CRS is NAD83 UTM 10N throughout, for my home area at least. There are many realizations of NAD83. Anything you did last year is likely in "NAD83(2011) epoch 2010.0" if you are in the US and firmly on the North American plate, and in Canada likely in NAD83(CSRS) apparently in a province-dependent epoch. The recent realizations are close enough that neglecting this won't hurt too much, but if you are going to call 1m an error rather than a match, you should be careful about this. If you are in an area with ground motion (e.g. Pacific Plate) then you have a lot more to do. The other big thing that's missing is what the trimble software is doing about datum transformations (or not, if the reference station coordinates are in NAD83(2011) as I'd expect). > None of these steps offer any option to choose or modify the Base > Station CRS so I don't think that would be the culprit in my NW > data offset, although maybe I've missed something. I think it's necessary to understand what's going on inside the software. > Last fall I collected quite a few points in an attempt to > quantify the problem, if that's what it is. Here are some > summaries: As Nicolas said, you are talking about "known" but have not explained where those coordinates came from and their expected errors. I also can't figure out your color scheme, and whether you are measuring 2 marks or one, etc. Data from the receiver in no-differential pseudorange solutio mode (not sure what "uncorrected" means) is going to be in WGS84(G1762), probably labeled as WGS84, which is different than NAD83(2011), and that needs a datum transform. In QGIS, that often ends up with a null transform, which is wrong. So there's a good question about what is going on within Pathfinder Office with datum transforms, which you need to find out from Trimble docs or support.
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