Global Positioning System Control/User Segments. Volume III. User Segment Description, Performance, Error Budgets, and RF Link Budgets.

The User Segment includes navigation hardware necessary to determine position or navigation data of the user in earth-centered coordinates. As such, it accomplishes receiver and computational functions. The User Segment measures pseudorange and range rate using the navigation signals from each of four satellites. Each satellite signal carries satellite ephemeris data, time bias data and other data necessary for the user ReceiverProcessor to convert the pseudorange and range rate to user three-dimensional position and velocity and system time. This positional information is determined in earth-centered coordinates which can be converted to any coordinate frame or units of measure that the user requires. The User Segment consists of military navigation equipment for various aircraft and surface uses. Users generally define six classes of user equipment. The classes categorize the user community as functions of mission requirements, electromagnetic environment, vehicle dynamics, and vehicle constraints. The User Segment includes an Antenna, Receiver, Processor, ControlDisplay Unit, Interface, Power Supply and Auxiliary Sensors as appropriate.