Downloading Base Station Data directly from NGS

Answer

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.

Solution:

NGS has been notified about the problem and they are working on a solution.  There are a couple of ways to obtain CORS base station data from the NGS website to process your data in Pathfinder Office (PFO).

Option 1

1. Find out the date and local time for the data you collected.
   1. Open PFO
   2. Open your ssf file
   3. Open Feature properties (Data and check box next to feature properties)
      • Look at the first record and the last record
        • Take note of the date and time
        • Note* make sure PFO has the correct time zone set to match the location of the data collected.
2.  Download CORS base station data manually from NGS website using theStandard Download
   1. First, you need to get the station ID you want to use
      • Go to http://www.ngs.noaa.gov/CORS/
      • Click on the state you are working in
      • Click on the station you want to obtain data from
      • Remember the CORS station ID (4 letters)
      • Click on Standard Files link on the left side of the website
   2. Under SITE, highlight the Station you want to get data from
   3. Under OPTION, highlight RINEX2Data
   4. Choose the Year
   5. Choose the Month
   6. Choose the Day
   7. Click on Find Files
   8. If you collected data the same day you are going to differentially correct the data:
      • Click on View then Details
      • Choose the files with the times that match your data collection times.
      • Right Click on the ****2560.07o.gz  file and save target as
      • The **** represents the 4 letter ID of the station
   9.  If you are differentially correcting data you collected from previous days the files will be consolidated into one.
      • Right Click on the ****2560.07o.gz  file and save target as
      • The **** represents the 4 letter ID of the station
   10. Save it/them to your base folder
   11. Click on the link Up to higher level directory
   12. Scroll to the bottom of the page
   13. Copy the broadcast file brdc2560.07n.gz to your base folder
   14. Change the first four letter of the brdc2560.07n.gz file to match the four letters of your base station
3.  Differentially Correct your data
   1. Open PFO
   2. Click on Utilities/Differential Correction
   3. Choose your ssf file
   4. Processing Type: Choose Automatic Standard Carrier and Code Processing
   5. Click Next and Next again
   6. Base Data Page
      1. Choose the Folder Search option
      2. Click on the Select button and navigate to the Base folder of your project (You should have saved the files from the NGS website here earlier.)
      3.  Reference Position
         • Choose Use reference position from base provider
           • Click on Select and pick the base station that matches the data you downloaded.
         • If you see a 2 meter offset, select from base file.  There are datum issues sometimes.
      4.  Make sure to check the box next to Confirm base data and position before processing
      5.  Continue on normally with the differential correction process
      6. Confirm Page
         • Look at the Coverage Details – you’re looking for 100% coverage

Option 2

1. Follow steps 1 and 2a from above.
2. Go straight to the NGS CORS ftp server
   • ftp://www.ngs.noaa.gov/cors/rinex/
   • Click on the folder with the year you want
   • Click on the day of the year you want
   • http://www.vpcalendar.net/Julian_Date.html
   • Copy the broadcast file brdc2560.07n.gz to your base folder
   • Change the first four letters of the brdc2560.07n.gz file to match the four letters of your base station
   • Click on the station you want (4 Letter ID)
   • If you collected data the same day you are going to differentially correct the data:
     • Click on View then Details
     • Choose the files with the times that match your data collection times.
     • Right Click on the ****2560.07o.gz  file and save target as
     • The **** represents the 4 letter ID of the station
   •  If you are differentially correcting data you collected from previous days the files will be consolidated into one.
     • Right Click on the ****2560.07o.gz  file and save target as
     • The **** represents the 4 letter ID of the station
3. Follow step 3 from above