Navigational systems throughout history have been constantly refined. Satellite systems, created in the middle of the last century, through systems that use Doppler's effect developed according to systems that measure the pseudorange. The strongest representative today is GPS, the central theme of this paper with an emphasis on describing GPS systems and devices that receive and process satellite signals. Work has been conceived in several units. The introduction briefly describes the history of satellite navigation and its features. After the introduction, the theory of satellite navigation and general movement of the body in the orbits is explained. Next, the GPS system's operation by segments and the GPS reception method are described. Also mentioned are DGPS systems and antenna systems also types of GPS receivers, receiver architecture and generally their mode of operation. It was also inevitable to look at the Russian GLONASS system and the hybrid GPS + GLONASS systems. At the end of the work, a portable Garmin GPS receiver is described as a short review and receiver test.