GPS Ephemeris Data

See Also: GPS Links    GPS Info    GPS Workshop

 

See Also:

            Planning software notes and examples (free software from Trimble)

            Quick Plan information notes and examples (Trimble software that comes with Pathfinder Office)

 

GPS satellites transmit information about their location (current and predicted), timing and 'health' via what is known as ephemeris data. This data is used by the GPS receivers to enable them to estimate location relative to the satellites and thus position on earth. It can also be used to predict satellite conditions in the future providing a tool for planning when (or when not) to schedule GPS data collection. Ephemeris data can be downloaded from certain GPS receivers (typically the higher end receivers such as the Trimbles) or downloaded from the Trimble website.

 

Once you download the latest GPS almanac (the ephemeris data) it can be used in either Trimble Pathfinder Office or Timble's free Planning software to display projected satellite configuration geometry for a given date and location.

 

Ephemeris data is considered good for up to 30 days (maximum). If you are attempting to predict GPS conditions for weeks into the future it is recommended that you repeat your predictions a week or two before collection to verify the results (satellite conditions are constantly changing).

 

 

Download Current Ephemeris Data (.alm format) for use with Trimble's Planning software

                For Firefox, right-click on the above link and choose Save Link As...

                For Internet Explorer, right-click on the above link and choose Save Target As...

        This will download a file (almanac.alm) that will need to be placed in the following folder:

        

                    C:\Program Files\Common Files\Trimble\Planning   

                (replacing the existing file of the same name)

 

 

Download Current Ephemeris Data (.ssf format) for use with Trimble's free Pathfinder Office (Quick Plan) software

                This link will download a file (current.ssf) that will need to be placed in the following folder:

 

                C:\Program Files\Common Files\Trimble\Almanacs
       or:    C:\Program Files (x86)\Common Files\Trimble\Almanacs

                 (replacing the existing file of the same name)