Figure 6-4. Doppler Shift - Comtech EF Data SNM-1001L Installation And Operation Manual

SNM-1001L Satellite Modem
Clocking Options
N
S
N
S
SATELLITE MOTION AND ORBITAL INCLINATION
GEO-SYNCHRONOUS
INCLINED ORBIT
GEO-SYNCHRONOUS
EQUATORIAL ORBIT
A
C
B

Figure 6-4. Doppler Shift

A
SATELLITE
NOMINAL
POSITION
SATELLITE
N/S
MOTION
6–6
Revision 1
MN/SNM1001L.IOM
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.
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.
THE N/S MOTION CHANGES THE
PATH FROM THE SATELLITE TO THE
EARTH, RESULTING IN FREQUENCY
CHANGES KNOWN AS THE DOPPLER
EFFECT.