I recently set up my Reach RS (latest v 2.3) over a base marker (PSU1b) and let it collect for about 25 minutes. My goal was to see what my post-processed positional accuracy is in good conditions (minimal interference from buildings/trees) and very near (less than 1km) a CORS station (PSU1).
Collection parameters: Reach RS was in static mode, solution status was reported as single in ReachView. The SNR bars were mainly >40 the whole time, and I’ve included the obs file so you’ll be able to see I had reasonably good satellite views.
My raw data in RTKPLOT has a large (and expected) spread, but the coordinates for PSU1b fall right in the middle. When I post-process, the Q=1 solution is more than a meter off of the reported PSU1b location. The images below show both the raw data and the processed data in the same plot -the processed data is at the origin on the plot. I have performed a datum transform on the reported location using NOAA’s HTDP tool (https://www.ngs.noaa.gov/TOOLS/Htdp/Htdp.shtml). In this case I only transformed the location reported on PSU1b’s data sheet.
I think the problem has to do with datum differences, but I haven’t found any information in the forums about converting the CORS files for use in RTKPOST. I have also been told that the .obs and .nav files are in satellite units and it’s only when RTKPOST gives the position file are the locations plotted in reference to WGS84. Do I need to transform the CORS data?
Does anyone have suggestions for improving my ppk results? The spread is quite small but that doesn’t help me at all if the accuracy isn’t great. I was hoping to get at least centimeter accuracy but if everything is correct, I’m looking at a couple of meters. Hopefully I’m missing something simple and I’ve just been looking at it too long to see it. Any and all suggestions welcome!
PSU1b’s data sheet: https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=AJ2131
Here’s a link to a folder with the following files in it:
- raw log file from collection (.ubx)
- .obs, .nav, and .sbs files from RTKCONV on the raw log file
- Folder containing .17o and .17n observation and navigation files from PSU1 CORS station
- Configuration file I used for RTKPOST called base.config