Global Positioning System Reference
In-Depth Information
Fig. 9. Positioning quality of a geodetic receiver when a MAC correction is used: CDF of the
planimetric error (top left) and of the elevation error (top right), cumulative moving average
of the planimetric error (bottom left) and of the three-dimensional positioning error (bottom
right)
The curves above confirms what was expected. Analysing, for example, the CDF curves of
planimetric and elevation error, it is possible to see how positioning errors do not increase
excessively when switching between the “red” and the “green” network. In these cases, the
positioning quality is similar, and reaches about 5 cms (95% of observations) in planimetry
and about 10 cms in altitude. A significant positioning deterioration occurs when differential
MAC corrections broadcasted by the “blue” network are used. In this case, the master
station is very far from the rover, causing problems on the quality of the positioning (15 cms
in planimetry and 25 cms in elevation).
The trend of cumulative moving averages allows to highlight once again the similar
behaviour of the MAC positioning performed with a “red” and a “green” network, as seen
in bottom right in the Fig. 9. The cumulative moving average also shows how the MAC
positioning with the “blue” network is not perfectly consistent over the time: as it is possible
to see, after about 8 hours of measurement there is a worsening of the three-dimensional
positioning quality, due to measurement error variations that are not well modelled by a so
wide network.
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