The objective of the diploma thesis is to compare the actual signal quality in selected locations with the coverage maps of the mobile operator. The places of interest with reduced level of signal strength are located in Brno and its surroundings. Theoretical part of the thesis discusses the issues of geographical information systems, GNSS technologies, mechanisms of signal propagation and mobile applications useful for surveying purposes. The practical part describes the communication with mobile operators, the process of data collection and processing the project using ArcMap software.