IntelliTrack Module
Operations Guide
AvL Technologies
| Proprietary – Content is Subject to Change without Notice
pg. 15
Figure 8 - Topographic Coordinate System
Each look angle measurement is converted to a direction vector in the Topocentric frame. In
order to more generally describe the satellite position, this Topocentric direction vector is
rotated into the Earth-Centered Inertial (ECI) Frame. The ECI frame is depicted as the
Cartesian [x,y,z] frame in figures 9&10 and where the x direction is aligned with the Vernal
Equinox, and the z direction is oriented north.
Figure 9 - Earth-Centered Internal Coordinate System
