Differential Correction Errors

Answer

Differential Correction Errors can result from a number of problems so I would go through the whole list to determine what the problem may be.

1. The NGS User friendly CORS download isn’t working properly for some stations and this is the same program Trimble’s Pathfinder Office Software uses.  This problem occurs when the base files don’t contain any information in the observation file.
2. You may not have the most recent updates for Pathfinder Office.
3. You may not have the appropriate Admin permissions set.
4. You may not have a current base station list.
5. The base station you are using may not be available at that time.
6. You may have tried to differential correct the data too soon after you collected the field data.

Solutions:

1. In the last month there have been several outages of the central site that manages links to CORS stations. This site is not controlled or managed by Trimble and we have no control over whether or when it is available. However, it is now back up and running but if you still experience problems inquiries can be addressed tongs.cors@noaa.gov.  There are a couple of ways to obtain CORS base station data directly from the NGS website to process your data in Pathfinder Office (PFO).  See the related article Downloading Base Station Data directly from NGS.
2.  Check Trimble’s website for the most recent PFO updates.
   • In Pathfinder Office, click on Help/Check for updates now.
   • Download and run the updates.
3.   Check to see if you have the appropriate Admin permissions set.
   • See the related article about PFO Admin permissions.
4.  Update your base station list in the differential correction wizard.
5.  Sometimes base stations temporarily/permanently go down.   The CORS website provides information on the CORS base station status.
   • Check for base station data availability
     • Go to this link http://www.ngs.noaa.gov/CORS/
     • Pick your state
     • Pick your station
     • Click on the Data Availability link on the left side of the website page
     • Look at the GPS date…you are looking for BLUE
   • Choose another base station
6.  Sometimes customers try to process the data too soon.  Usually the CORS stations post data every hour, but this isn’t always a guarantee.
   • Check for base station data availability (see number 5)
   • Try again later
7.  Sometimes it helps to delete everything out of your base folder
   • Navigate to your project folder
   • Open your Base folder
   • Delete everything in them
   • Try differential correction again