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SDM-300A Satellite Modem
A.2.1.4
Reed-Solomon Decoder
Refer to Figure A-18 for a block diagram of the Reed-Solomon decoder section.
The Reed-Solomon decoder section includes the following circuits:
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•
•
•
•
JP 2
R X S AT D AT
U N IQ U E W O R D
(S E R IA L)
JP 2
D E TE C TOR
R X S ATC L K
Figure A-18. Reed-Solomon Decoder Section Block Diagram
The data and clock signals come from the demultiplexer on the interface PCB, and are
sent to the Reed-Solomon decoder section.
The data is sent through a serial/parallel converter. Because it was block interleaved by
the encoder, the data must pass through a de-interleaver with the same depth as the
interleaver used on the encoder. The de-interleaver is synchronized by the detection of
the unique words, which are placed at the end of each page by the interleaver on the
encoder.
Once the de-interleaver is synchronized to the incoming data, the data is reassembled into
its original sequence, in accordance with the INTELSAT-308 Rev. 6B specification. The
data is then sent to the Reed-Solomon outer decoder.
Rev. 4
Serial/Parallel Converter
RAM Deinterleaver
Parallel/Serial Converter
Reed-Solomon Codec (decoder section)
Synchronous Descrambler
S E R IA L
R A M
T O
PA R A L LE L
D E IN T E R LE AV E R
C O NV E R TE R
U 3
U 3
D E IN T E R L E AV E R
A D D R ES S
G EN E RATO R
PA R A LL E L
R S
C O D E C
T O S E R IA L
(D E C O D E R S E C T IO N )
C O N V E RT E R
U 2
U 1
U 3
R S T IM IN G C O N T R O L LE R
U3
JP 2
D M X DAT
S Y N C H RO N O US
(S E R IA L)
D E S C R A MB L ER
D M XC LK
U3
U 3
JP 2
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