Abstract: On the basis of DDKIN software for processing kinematic observations on carrier phases and results for a vehicle-borne DGPS this paper discusses the following performances for GPS kinematic positoning:——to select a suitable positioning constellation to consider the User Range Accuracies (URA) provided by the navigation message of GPS satellites:——to make choise of a suitable antenna and its setting-up site based on features of the motional carrier:——to process finely 4000SST data at the update rate of one second to adopt Trimvec Plus and DDKIN software written by these authors.