Resumen
The uninterrupted information about user?s position can be obtained from satellite navigation systems (SNS). Currently (September 2017) two global SNSs, GPS and GLONASS, are fully operational, two next, also global, Galileo and BeiDou are under construction. Several hundred million receivers of these systems are used in the world in each mode of transportation, road, rail, maritime and air. The position?s accuracy depends on the parameters of SNS, user?s latitude and the visibility of satellites in restricted area. Last parameter must be taken into account in road transport in urban canyon, in particular the street orientation and its dimensions, the width and height of the buildings. The impact of satellite position on the effectiveness of intelligent transportation systems are described in this paper.