Comtech EF Data SDM-300L3 - Manual (Page 221)

SDM-300L3 Satellite Modem Revision 1
Clocking Options MN/SDM300L3.IOM
6–11
SATELLITE MOTION AND ORBITAL INCLINATION
SATELLITE
NOMINAL
POSITION
N
S
GEO-SYNCHRONOUS
EQUATORIAL ORBIT
GEO-SYNCHRONOUS
INCLINED ORBIT
SATELLITE
N/S
MOTION
N
S
A
B
C
A
AS STATION-KEEPING FUEL
BECOMES EXHAUSTED, THE N/S
STATION-KEEPING IS LIMITED
TO PRODUCE A MORE INCLINED
ORBIT, THUS PROLONGING THE
LIFE OF THE SATELLITE.
A SATELLITE IS MAINTAINED AT AN
ASSIGNED GEOSTATIONARY
LOCATION THROUGH THE USE OF
GROUND COMMAND ADJUSTMENTS
TO ITS N/S AND E/W LOCATION. THIS
PROCESS, KNOWN AS SATELLITE
STATION-KEEPING, IS USED TO KEEP
THE SATELLITE DRIFT WITHIN
CERTAIN BOUNDARIES.
THE N/S MOTION CHANGES THE
PATH FROM THE SATELLITE TO THE
EARTH, RESULTING IN FREQUENCY
CHANGES KNOWN AS THE DOPPLER
EFFECT.
F IGURE 6-7. D OPPLER S HIFT