Looking for the Satellite
As seen from a specific
Observer,
the satellite has 3 coordinates in a spherical
coordinate system:
Azimuth - the (true) compass direction to the satellite;
Elevation - the angle above the horizon; and Slant Range - the
distance to the satellite. In addition to the changing azimuth and elevation
(az/el - sometimes referred to as look angle), the changing range
causes a Doppler shift of the radio signals between the observer and the
satellite.