Global Positioning System Reference
In-Depth Information
between the “red” and the “green” networks (98-99% of epochs using 5 minutes files and 99-
100% using 10 minutes files). For the “blue” one, this percentage decreases to 92% and 97%
respectively.
Fig. 15. Positioning quality of a geodetic receiver after the post-processing with the nearest
reference station. CDF of the planimetric (left) and altimetric (right) error using static time
sessions of 5 (top) and 10 (bottom) minutes
These results clearly show what is the limit (about 2 cms) of the post-processing approach
when a master station is located farther than 25-30 kms from the rover. This distance is until
today comparable with the actual inter-station distances of GNSS networks. To improve the
2 cms limit with a reasonable reliability, two strategies can be adopted:
•
increase the static measurement length, resulting in a lack of the productivity;
•
use a post-processing network product, i.e. a virtual RINEX file generated from the
error models estimated by the GNSS network.
In the last case, the main advantage for the user consists in having a raw data file located
close to the rover.
In this way, the rover has a higher probability to fix the phase ambiguities. Otherwise, this
product shows the problems already discussed for the real-time VRS positioning. The VRS
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