# ![](media/image1.wmf)

# Standard Operating Procedures

# **Downloading and Correcting GPS Data**

10/17/02

\*\*When returning from the field, always bring in GPS unit to return to
office\*\*

## **Downloading Data**

-   Turn on Datalogger, set in cradle.

-   Click on "GPS Pathfinder" icon on desktop to open program (or click
    on "Start" Button, Select "Programs", and double click GPS
    Pathfinder on menu).

-   When the window opens, a "Select Project" pop-up will ask you to
    select a project name, (or just click "X" to bypass).

-   Along the top of the window, click "Utilities" and select "Data
    Transfer" from the pull-down menu. The "Device" column should say
    "GIS Datalogger on COM1". On the "Receive" tab, click the "ADD"
    button and select either datafile or waypoints (whichever you are
    trying to download).

-   Once the "Open" window pops up, click on the files you want to
    download (click on one, or to select multiple files hold down the
    "Ctrl" key and click), Click "Open". Make sure that the
    "Destination" window shows the correct folder you want your file in.
    Click "Transfer All".

-   A pop-up window will appear, saying whether or not the file was
    successfully transferred and will tell you a corresponding text file
    with log information. Click "Close".

-   In Windows Explorer, check destination folder to make sure files
    have transferred.

## **Correcting Data** 

-   Open GPS Pathfinder Office (see above).

-   On the menu along the top of the window, click "Utilities" and
    select "Differential Correction".

-   The Differential Correction window will appear. In the "Rover Files"
    box, select files to be corrected. If you just downloaded, they may
    appear automatically (if not, click on "Browse", select your files
    and click "Open").

-   In the "Base Files" box, select "Internet Search", make sure the
    window says "USFS- Prescott, AZ" and click "OK". Make sure in the
    "Corrected Files" box the window displays the folder you want your
    files in (if not, use the "Browse" button to find the right one).
    File extension should say "cor". Click "OK".

-   The program should automatically download the corrected base station
    files from the website. (If this **doesn't** work, see the next
    section- Manually Correcting Files).

-   The program will then give you a series of pop-up windows describing
    the status of corrections and percentages... if they are less than
    90%; check to make sure that accuracy is sufficient or try and redo
    the corrections.

## **Manually Correcting Files** 

-   Go to the website
    **http://www.fs.fed.us/database/gps/prescott.html**. From the
    pull-down menus, select the date for which you want corrections.
    Click "List CBS files for Download" button.

-   Files are named with two characters and then the date (Example:
    P2090101 for September 1, 2001). Click on the links for all the
    files with the appropriate dates. The computer will ask you if you
    want to open it or save it to your computer- save these files in a
    folder.

-   On the "Differential Correction" window, select files to correct
    (see above). In the "Base Files" box, select "Local Search" button.
    Use the "Browse" button to select the folder where correction files
    were saved, Click "OK" button. Make sure the "Corrected Files,"
    "Output Folder" box shows where you want your corrected files saved.

-   The program will then give you a series of pop-ups telling you the
    status of corrections and percentages... if they are less than 90%,
    check to make sure that accuracy is sufficient or try and redo the
    corrections.