Insatellite communications, there is the ground segment and the space segment. The ground segment comprises all communications technology facilities on earth. It is the ground station with its antennas and receivers and its connections to other ground stations, implemented via gateway stations for connection to mobile and fixed networks.
The ground segment includes equipment and components located outside and inside the building, the outdoor units( ODU) and indoor units( IDU). Ground unit equipment and components include the parabolic antennas with LNB converters, the receiving and transmitting equipment for the downlink and the uplink. To the indoor units, that is the receiver, the receiving equipment and the equipment and systems for signal processing.
In GPS systems, the ground segment consists of the control segment with the monitor stations, the main control station and the ground transmit stations. The monitor stations contain the receiving equipment with the receiving antenna, a cesium standard and the data processors. The ground transmit station contains, among other things, the RF power amplifier and the transmit antenna. In addition, there is the user segment with the navigation device for receiving the GPS signals.