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SLM-7650 Satellite Modem
Theory of Operation
TX OVER
HEAD
PROGRAMMABLE
TEST PATTERN
OVERHEAD
GENERATOR
INTERFACE
RX OVER
HEAD
SD
EIA 422/530
TT
OPTIONAL
ST
PLUG-IN
DDS
INTERFACE
CLOCK
M C
RECOVERY
EXT REF
(1,5,10MHz)
REF
PLL
PROGRAMMABLE
TEST PATTERN
DETECTOR
RX_C
RX_D
SERIAL
M&C
ALARM
INTERFACE
FAULT
INTERFACE
ETHERNET
(Optional)
OVERHEAD
MUX
(INTELSAT, NON-
(PROGRAMMABLE)
TX OVER
INTELSAT, DEMAC)
HEAD
MOD
ST REF SEL
TIMING
SOURCE
INT_REF
RX_CLK
ST
ST
PLL
M C
DATA
INT_RE
INT_REF
F
OSC
INT_REF
TT
BUFFER
RX_CLK
PLL
MC
BUFF REF SEL
RX OVER
HEAD
OVERHEAD
DE-MUX
DE-INTERLEAVER
BUFFER
(INTELSAT, NON-
RX_CLK
(PROGRAMMABLE)
INTELSAT, DEMAC)
RX_DAT
KEYPAD
PROCESSOR
&
DISPLAY
Figure 4-1. System Block Diagram
UNCODED
SCRAMBLER
FORMATTING
R-S ENCODER
INTERLEAVER
OM73
SCRAMBLER
CONV/TCM
ENCODE
TX R-S
BYPASS
TURBO CODEC
W/ SCRAMBLER
& DESCRAMBLER
& SYMBOL
CLOCK
FORMATTING
DISTRIBUTION
RX R-S
VITERBI/TCM
BYPASS
DECODE
OM73
DESCRAMBLER
DESCRAMBLER
R-S DECODER
UNCODED
FORMATTING
4–2
Revision 4
MN/SLM7650.IOM
I
MAPPER
QAM
TX DE-JITTER
PRE-
TX FILTERING
Q
PROCESSING
I_R
CARRIER/
I_SOFT
CLOCK
DEMOD
Q_SOFT
LOOP &
Q_R
FILTER
70/140MHz
TX IF
70/140MHz
I F
LOOP
BACK
RX IF
70/140MHz
70/140MHz
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