39. I've noticed that one of your sites has varying coordinates for the base station. The Rinex file displays one coordinate while the property box in my manufacturer's software displays another with the WGS as a reference frame. I thought I could find the correct coordinate by visiting the CORS website and looking at the data sheet, but that gives me another coordinate. Which is correct?
We supply 2 positions for our CORS users. The L1 Phase Center (L1PC) and the center of the bottom of the antenna which we call the antenna reference point (ARP). We supply these positions in 2 reference frames, NAD83 (epoch 2002.0) and ITRF00 (epoch 1997.0) . We do not use the WGS84 to position points. You can read more about WGS here ...... http://www.ngs.noaa.gov/CORS/Articles/Reference-Systems-Part-3.pdf
Here is the file (coordinate file) which shows the positions for EPRT
ftp://www.ngs.noaa.gov/cors/coord/coord_00/eprt.
You can get any coordinate file by changing the site_ID in that link.
The datasheet will only show positions in NAD83 (not ITRF) and may show other control marks. The datasheet lists each mark with a PID. The PID for EPRT's L1 phase center is AH5047. The PID for the ARP is AH5046 .
Consider the coordinate in the rinex file header and station logs as APPROXIMATE. Always use the Coordinate file (Position Velocity file) position. It is the policy of NGS to overwrite the appoximate position in the header with the published NAD83 position, but some older files may not have these corrections.