A radiator for a satellite intended for being placed in geostationary orbit around the earth in a tilted plane relative to the plane of the ecliptic, includes at least one panel having at least one radiative surface, and including: a mounting foot supporting the panel; and control and motor elements for pivoting the mounting foot about an axis of rotation tilted relative to the radiative surface which is perpendicular to a radiation axis, the radiation axis and the axis of rotation being tilted relative to one another by a non-zero working angle, corresponding to the tilt angle of the plane of the orbit of the satellite relative to the plane of the ecliptic, the working angle being fixed, such that for any rotation of the mounting foot about the axis of rotation owing to the control and motor elements, the radiative surface remains parallel to the plane of the ecliptic.

A three-dimensional map of an environment with buildings is used to computationally predict locations and times of global navigation satellite system (GNSS) blockages. For example, in urban environments some of the GNSS satellites are occluded by buildings. These blockages can be modeled. A computing system can make a map showing which satellites are or are not visible as a function both of location and time. The map can be used by a mobile GNSS receiver to determine which satellites to use or whether to use a backup system for navigation. The system can determine when a given satellite will enter or leave a GNSS receiver view during a route. The map can be stored in the GNSS receiver (or a host of the GNSS) or can be stored by a network service. This mapping can be used to predict multi-path effects of a satellite transmission at a location.

A method for controlling an antenna of a mobile communication application system based on double quaternions in MEMS inertial navigation. The method comprises: introducing an antenna control quaternion based on a navigation attitude quaternion; in each interrupt cycle of a navigation computer, updating the two quaternions respectively using a carrier system measured by a gyroscope relative to a rotation vector of an ideal platform coordinate system; in each filter cycle, correcting the error of the navigation attitude quaternion respectively using a Kalman filter; according to the relationship between the attitudes determined by the two attitude quaternions, determining the angular speed in an antenna control instruction; and finally, driving a servo system to rotate at an antenna servo control angle converted by an antenna control quaternion attitude.