GNSS receivers are electronic devices that receive and digitally process the signals from one or more GNSS satellite constellations in order to provide the user position, velocity and precise time (PVT). They act as the user interface to any GNSS.
Every GNSS/GPS satellite transmits a signal, which has a number of components including carrier frequencies, digital codes and a navigation message. The carriers and the codes are then used to determine the distance from the receiver to the GNSS satellite, and the navigation message contains, among other information, the location of the satellites as a function of time.
Why Are GNSS Receivers So Precise?
GNSS receivers determine their position using four factors: longitude, latitude, height and clock error, and any navigation solution provided by a receiver is based on the computation of its distance from a set of satellites.
The transmission of signals is controlled by highly accurate atomic clocks on board the satellites, and as such, receivers can calculate the time taken for the information from the satellite to reach the receiver. Since the exact satellite positions are known, it then becomes possible for the GNSS receiver to calculate its exact distance from the satellite.
GNSS receivers need at least four satellites to obtain a position, and there must be a line of sight between the receiver’s antenna and the four satellites. The use of more satellites, when available will improve the position solution, but not every receiver will have the ability to make use of additional satellites.
The receiver’s ability to, and the way in which it uses additional satellite signals will of course vary depending on the model of the receiver. Receivers also vary in terms of which constellation or constellations they track, and how many satellites they track simultaneously. Receivers can be packaged for use in a specific application, such as aviation or agriculture, for example.
Besides position, GNSS receivers can also provide users with very accurate time by synchronizing their local clock with the highly accurate atomic clocks on board the satellites. This precise time is used in financial networks, cellular systems, the internet, and in the synchronization of power grids.
