Figure 3-33. Doppler Shift - Comtech EF Data SDM-300A Installation And Operation Manual

SDM-300A Satellite Modem
N
S
N
S
Rev. 4
SAT ELLITE M O T IO N AN D O R BITAL IN C LIN AT IO N
GEO -SYN C H R O N O U S
IN C LIN ED O R B IT
GE O -S YN C H R O N O U S
EQ U ATO R IAL O R B IT
A
C
B

Figure 3-33. Doppler Shift

A
A S ATE LL ITE IS M AIN TAIN E D AT A N
AS SIG N ED GE O S TATIO N A RY
LO C AT IO N TH R O U G H TH E U S E O F
G R O U N D C OM M A N D AD JU ST M E N T S
TO IT S N /S A N D E /W LO C ATIO N . TH IS
S AT ELLIT E
PR O C E SS , KN O W N AS SAT EL LIT E
N OM IN AL
STATIO N -K EE PIN G , IS U SE D TO KE EP
PO S IT IO N
T H E SATE LLITE D R IFT W ITH IN
C ERTAIN B O U N D A R IES.
A S STATIO N -KE EPIN G F U EL
B EC O M ES E XH AU S T ED , T H E N /S
S TATIO N -KEE PIN G IS LIM IT E D
TO PR O D U C E A M O R E IN C LIN ED
O RB IT, T H U S PR O LO N G IN G T H E
LIFE O F T H E SATE LLIT E .
T H E N /S M O T IO N C H A N G ES T H E
PATH FR O M T H E SATE LLITE TO TH E
EA RTH , R ESU LTIN G IN F R EQ U E N C Y
SAT ELLIT E C H A N G ES KN O W N AS TH E D O PP LE R
EF FEC T.
N /S
M OT IO N
Operation
3–95