4-20
An ECLIPSE is when the satellite is not in view or in direct line of sight with the sun. This happens
when the earth is between them.
An EPHEMERIS is a table showing the precalculated position of a satellite at any given time.
PROGRAMMED TRACKING uses known satellite orbital parameters to generate antenna
pointing angles.
AUTOMATIC TRACKING is done by the equipment comparing the direction of the antenna axis
and the direction of the received signal.
HAND OVER is the period of time for one earth terminal to yield control to another as a satellite
moves out of its area of coverage.
SATELLITE-SUN CONJUNCTION is when the satellite and sun are close together and the noise
from the sun prevents or hampers communications.
A SATELLITE ECLIPSE is an eclipse where the rays of the sun don't reach the satellite. This
prevents recharging of the solar cells of the satellite and decreases the power to the transmitter.
The ZONE OF MUTUAL VISIBILITY is where the satellite can be seen by both the up- and
down-link earth terminals.
