Tracking and Display of Earth Satellites

In a new method of displaying the predicted paths and real-time positions of artificial earth satellites, cathode-ray tubes are used with two types of map overlays: orthographic projection and Mercator projection. Functions to match these projections are generated electronically. Auxiliary satellite information is cataloged and made available through "light gun" interrogation of the satellites displayed on the CRT. The display and orbit simulator can be used as an integral part of a live tracking system. A mathematical derivation of the subsatellite path on the orthographic projection is given.