Ground stations are the link between the control system and a satellite in orbit. They track a satellite's signal to find it's location, and the status of equipment onboard and distribute that information to interested parties. They are also used to transmit operational signals back to the satellite to help control it.
Data collection, receiving or processing facilities located on the ground used to receive imagery from satellites.
The satellite equipment located on the ground that controls the satellite and the information that is sent and received by the satellite.