Geode Features; Accuracy And Precision - Juniper Geode GNS3 User Manual

Geode GNS3 Real-Time Sub-Meter GPS Receiver

2. Geode Features

The Geode is a real-time, sub-meter, sub-foot, or decimeter
receiver. This means the Geode is able to deliver sub-
meter, sub-foot, or decimeter accuracy, depending on the
configuration, with 95–98% precision in the very moment
the data is being collected. This is the cutting edge of
geospatial technology. Historically, this level of precision and
accuracy was only available via post-processing software or
expensive survey-grade equipment.

2.1 Accuracy and Precision

It is important to note that in the context of GPS, accuracy
and precision are related, but not the same thing.
Accuracy refers to the radius of the circle of unknown
around a true point. The smaller the radius, the higher the
accuracy. The Geode has sub-meter, sub-foot, or decimeter
accuracy. This means the Geode can plot a position to
within a sub-meter (or better) radius of the true point.
Precision refers to repeatability or how frequently a receiver
can plot a point inside the circle of accuracy and whether or
not that circle is centered over the true point.
Over time, any stationary GPS receiver will plot multiple
positions for a given point. This happens because of errors
caused by variables in the satellites, the surrounding
physical environment, and the ionosphere. Modern
geospatial technology has
made huge progress in
correcting for those errors,
but a receiver's real-time
accuracy is dependent on its
ability to process those
corrections. The points
plotted by the stationary
receiver eventually form a
scatter plot. Precision is the
percentage of points on the
scatter plot that fall within
the circle of accuracy.
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Chapter 2 Geode Features