The accuracy of the global positioning systems

In certain cases, due to such high precision of geographical position estimation, there problems connected with the accuracy of systems for the projection of the globe convex surface to the two-dimensional surface of a chart emerge. When using DGPS, one should pay closer attention if the chart datum is compliant with GPS. Although DGPS can increase the precision of the SPS several times, the accuracy improvement of the PPS is very limited. Satellite navigation systems used for non-military purposes found their application mainly in maritime and aerial navigation; however, recently they started to invade inland applications. Expensive cars are being equipped with such systems, which transmit signals from remotely controlled transmitters hidden in vehicles in case of theft. Today, one can buy an inexpensive GPS or DGPS receiver capable of displaying position and travelled distance on a map of any selected region, in selected scale and with a variety of useful information such as location of hotels, restaurants, museums, or gas stations. Many developed countries are beginning to implement GPS receivers equipped with an interactive vehicle communication system that connects them with traffic control centres.