Antennas for Global Navigation Satellite System Receivers
Table 14.1 lists four major active and planned global navigation satellite systems (GNSS) that allow the determination of the position (longitude, latitude, altitude) of a GNSS receiver. Each receiver receives pseudo-random noise (PRN) code sequences from a constellation of GNSS satellites that are orbiting the Earth at different medium Earth orbits (MEOs) to broadcast satellite signals covering the entire Earth's surface. The total system is separated into three segments: namely, the control, space, and user segments . The control segment includes a network of command centers on the ground and is responsible for maintaining satellite position, adjusting satellite clocks, and uploading navigational data. The space segment includes a constellation of satellites that broadcast their times and positions. The user segment receives satellite signals and derives its position using trilateration methods based on estimated distances to four or more known satellite locations from which the signals are received . Each satellite signal contains the identification, positions, and sending time of the initiating satellite. Although this trilateration positioning concept is mathematically straightforward, in practice, obtaining an accurate range between a receiver ...