One of the basic tasks of geodesy is determination of accurate position (coordinates) in terrestrial coordinate systems. Due to a rapid technological and satellite geodesy development, also a common user nowadays is able to find out his position accurately, despite not being familiar with concepts of satellite aided positioning. Besides position itself, the position quality is of great importance. We may stress that nor GNSS nor GNSS-receivers do not provide relevant information regarding quality of acquired position. Absence of relevant information about positioning quality was the motivation for our testing of few GNSS sensors, available in present-day single-frequency GNSS receivers. GNSS and supporting systems, used by single-frequency GNSS receivers are also described. Two tests were set up for testing position quality: static and kinematic mode. Both were conducted in »near perfect« and difficult conditions. for the reception of satellite signal.