UPDATE (Aug 2009): With some prompting Trimble has added AREQ back in the list of SOPAC reference stations for differential correction. If Arequipa Laser Station (AREQ), Peru doesn't appear in Pathfinder Office Differential Correction provider list, click the "Update List" button.
The Arequipa base station operated by the International GPS Service (IGS) no longer appears as an available base station in the Trimble - Differential Correction list (GPS Pathfinder Office, GPS Analyst), though the data continues to be served by the Garner host at UC San Diego.
The following settings allow you to post-process data from Trimble GPS receivers directly in Pathfinder Office/GPS Analyst. This information is based on software versions from 2006, and full install and updates to Pathfinder Office are available online from Trimble.
In the Differential Correction wizard under "Base Provider Search" click "Select". Note that AREQ, the Arequipa base station no longer appears in the available list altough other SOPAC base station are available.
Choose the station listed as "SOPAC, UNSA Salta, daily" and click Copy...
Click Properties... and change the settings to match the following
General
Organization: SOPAC, Arequipa Peru
Station Location: Arequipa, Peru
Base Station
Receiver Type: ROGUE SNR-8000
Latitude: 16°27'55.8612"S
Longitude: 71°29'34.0680"W
Altitude (m HAE): 2,488.9266
Internet Server
Base file address format:
ftp://garner.ucsd.edu/pub/rinex/%YYYY%/%DDDDD%/%CCCC%%DDDDD%0.%YY%d.Z
Use GPS Time (UTC)
Station ID: areq
RINEX Format
Nav File Address Format:
ftp://garner.ucsd.edu/pub/nav/%YYYY%/%DDDDD%/%CCCC%%DDDDD%0.%YY%d.Z
Website link
http://sopac.ucsd.edu/sites/
You can manually visit the webpage where these data are hosted from here
http://garner.ucsd.edu/pub/rinex/
or ftp://garner.ucsd.edu/pub/rinex/
Then by /year/GPSday/
This allows you to download the data yourself and place it in the /Base/ folder for post-processing but you must calculate the GPS week and day yourself and manually gather each of the necessary files. See the CORS GPS calendar online.
Depending on your correction needs you may want to choose "Output Positions: Corrected and Uncorrected" in Change the "Correct Settings" under "Output". This is a more inclusive setting so that uncorrected positions are retained but with Corrected positions taking precedence.