Comtech-ef-data SDM-300A User Manual download pdf (Page 231)

SDM-300A Satellite Modem Revision 6

Buffering SDM300A.IOM

8–3

S

A

T

E

L

L

I

T

E

M

O

T

I

O

N

A

N

D

O

R

B

I

T

A

L

I

N

C

L

I

N

A

T

I

O

N

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.

Figure 8-2. Doppler Shift

1 2 ... 226 227 228 229 230 231 232 233 234 235 236 ... 469 470

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