Spatial Analysis Lab (SAL)

Using Trimble's Quick Plan Software
For GPS Condition Predictions

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See also:   Ephemeris Data (downloading)
                Trimble's Planning software is a free, stand-alone application that does the same thing as
                    Quick Plan, which can be downloaded for free here.

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The current and predicted GPS Satellite locations and timing are contained in what is known as the ephemeris data. This data can be used to predict GPS satellite constellations in the future and thus can be used for scheduling so as to maximize the quality of data collected.

Quick Plan is a part of Trimble's GPS Pathfinder Office software and uses downloaded ephemeris data for satellite predictions. The downloaded ephemeris almanac (current.ssf) is typically stored in the C:\Program Files\Common Files\Trimble\Almanacs folder). By knowing in advance which times of day will have better or worse satellite configuration conditions you can schedule your data collection so as to maximize your positional accuracy. For more information see the Quick Plan help files.

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Below are examples of predictive graphs generated with Quick Plan


Chart showing Number of satellites (Nsats, more is better) and Quality of Satellites (PDOP, a Lower PDOP is better) for a 24 hour period of time (for a chosen date and location). PDOP = Positional Dilution of Precision, a measurement of the overall satellite quality.


Example of a SkyPlot - showing which satellites will be visible for a chosen location and date.


Chart showing which satellites are available (visible), and when for a chosen date and location.


Chart showing Elevation of visible satellites for a chosen date and location.

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