Not sure why my platt is not lining up the facet postion. My corrections are from State COR nad 83. The platt is the same. I verified the same monument the surveyor used. I have solid fixed postions on over 20 metal stakes. All the angles are off a little and distances are within a foot. What am I missing.
Run through this accuracy verification guide and see how that shakes out
Do you have RINEX observations from the CORS? Or a site log for equipment / settings? The NOAA CORS typical show equipment changes (receiver, antenna), and firmware updates, current survey / re-averaging, shift-corrections, etc.
Check also the email of the site manager, perhaps chat with them.
I’m highly doubtful the RTCM3 is in NAD83 datum.
Can you plug it’s coordinates into Google Maps and sight the antenna, vs that of the monument?
I’d expect some offset in the satellite imagery, but some local consistency to that.
Could be a number of things.
Was the Professional Land Survey performed with conventional tools ?
It’s typical for most of the corners to be occupied with a total station, and a least squares analysis performed to adjust all measurements. This can change both distances and angles that appear on the final Plat.
How many points on the Plat are labeled with Coordinates?
Your Plat is likely Ground Coordinates and the GNSS is giving you Grid Coordinates.
You must apply the appropriate scale factor to compare.
Are all 20 corners in good locations for observing GNSS ?
Are you able to prove repeatability in your GNSS measurements?
The Professional Land Surveyor also had to rely on Evidence And Procedures.
IE: a pre-existing mark will usually be the ground truth even when it’s measurements (previous plat/survey/deed verse ground) disagree.
There are many more possibilities.
Mount Point is VRS_RTCM32 NAD83(2011)
All gnss measurements are repeatable, Only 5 or 6 are in clear view of the sky.
I check two monuments, they are dead on. NAD 83 (2001)
It appears that the rotation was established by the 722’ baseline that’s labeled with State Plane Coordinates. The monuments and pins were likely shot in a conventional survey. The closure error for the entire boundary was likely later “spread-out” via a least squares adjustment. When comparing GNSS measurements to your Professional Survey, you will notice a slight difference in Angles and distances between points because of the least squares adjustment and the need for using the scale factor (to compare Grid vs Ground distances).
Example on Scale Factor:
Imagine you were to use a theoretical perfect (calibrated tension and temperature) 1,000’ long tape measure to establish a 1,000.00’ baseline in a perfectly flat field. Then you perform a 3 day survey with a good GNSS and post-process both baseline endpoints. The GNSS points will not be 1,000.00’ apart without applying the Scale Factor to move from Grid Coordinates to Ground.
Both measurement techniques are correct, accurate, and repeatable, but they are not the same by definition.
I see this in my State’s CORS network also. Keep in mind that the CORS Base Station, the “D WILSON” control point, all R/W monuments, etc, have been on the move since 2011.
The CORS is broadcasting correction data from it’s “known” position from a long time ago.
It’s normally not a big deal but we have to be mindful of what data we’re working with.
IE: If you throw in a new (accurate) PPP solution today on a mark it wouldn’t play well with the CORS Network that hasn’t been updated with respect to time.
What is a good easy to learn post desktop software. I have using swmaps to collect stake position.
Looking at QGIS software, but there is alot to learn.
QGIS is our recommendation for Windows Windows - SparkFun RTK Product Manual
They have pretty good docs here and you can probably find guides/videos for specific workflows
You’re right there is a lot to learn with QGIS, but you also don’t have to learn all of it. I use QGIS for work multiple times a week, and I only know probably 5% of what it’s capable of doing. It seems that most workflows are pretty simple once you’ve become familiar with the interface.
How far off will points on the survey be after 20years. Are we talking about inches?
You can find out exactly with the guide that @TS-Russell linked to in Post #2.
It’s an extremely helpful guide 
Keep in mind that the physical marks shown on your survey plat have also been moving at the same rate as the nearby NC CORS Base Station, so the movement likely isn’t a big deal to you when using that CORS Base for RTK corrections (depending on how/when the State Plane Control Points were collected for the Plat).
It can be a large source of “perceived” error if you use a RTK correction source that is updated on a regular basis (PointPerfect, etc) or a position that’s post processed with PPP, when comparing to “old” coordinates.
These are just some examples of why we need to keep in mind the sources of data when we try to compare results. They may or may not have much impact on your specific project.
It would be helpful if someone would do a youtube video on using the Qgis for basic offline surveying. For people not familiar with surveying and terminology used.
Might I suggest reading
I feel like while GNSS is an amazing tool it takes a bit of concept understandings
You may find a PDF copy on a Anna’s archive
One thing that may help you is not focus so much on the coordinates themselves but rather capture known points, draw the record in qgis and then shift the record to your captured points, from that you can create search points if that’s why you’re attempting to do.
Also as a land surveyor I’ll preface be careful what activities you’re doing so you’re not surveying without a license.
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I am only looking for stakes and building a good map for land I own.
Re reading, I am wondering if you’re calculating grid distance instead of ground distance. Usually records of survey are scale factor 1 ground distance when shot with conventional total station. Your GNSS is usually gonna give you grid distance.
All of my stakes are line of site except one . Which is1400ft up hill then down to a creek. All Woods. The measures on one deed is from before 1945
Down loaded the GPS and GNSS for Land Surveyors, Fifth Edition. 800 pages with lots of info to learn.
Can Qgis convert points Grid to Ground.
Grid to ground is a scale factor you multiply points by its usually very small where I’m at in Oregon but not sure about your location.
https://www.ngs.noaa.gov/NCAT/
You can use ncat to input your GNSS coordinates and see if there’s enough scale factor. Also if it’s an old deed are you sure the measurement is correct? Does it show on the plat? The plat looked more recent.
Another thing to consider is an old survey could say 100 foot for a course between two monuments and in Oregon if you measured 105 today but the monuments were original they would hold over 100 foot course. Again different states may be different. I know some states hold angles over distance calls.
What the best Qgis plugs-in for working with offline surveys