It is worth mentioning that, in the differential
procedure there is an extra communication between
the reference and the mobile receiver
through a terrestrial radio-navigation system (very
high frequency––VHF system) in order to transfer
different kind of corrections (e.g., meteorological
etc.) from the reference to the mobile stations. This
results to a considerable improvement of the determination
accuracy of the position vector. The
differential procedure is today a more powerful
tool for applications related to combination procedures
of GPS especially with geographic information
systems (GIS). Moreover, absolute positioning accuracies better than one meter, can