Reed-Solomon Decoder; Figure A-4. Reed-Solomon Decoder Section Block Diagram - Comtech EF Data SDM-9000 Installation And Operation Manual

SDM-9000 Satellite Modem
A.1.2.2 Reed-Solomon Decoder
A block diagram of the Reed-Solomon decoder section is shown in Figure A-4. The
Reed-Solomon decoder section includes the following circuits:
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•
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•
•
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3 CHANNEL
RXSATDAT
JP2
SERIAL
(SERIAL)
UNIQUE WORD
RXSATCLK
JP2
CORROLATER
U9

Figure A-4. Reed-Solomon Decoder Section Block Diagram

The three channels of serial data and the clock signals come from the demultiplexer on
the interface PCB and are sent to the Reed-Solomon decoder section through connector
JP3.
The data is passed to a 3-channel serial corrolater which locates the unique words and
reformats the data to 8 bits on the appropriate byte boundaries.
Because the data was block interleaved by the encoder, 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
RS frame 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 IESS-308 Rev. 6B specification. The data is then sent to the input FIFO and on to the

Reed-Solomon decoder.

Rev. 4
3-channel serial unique word corrolater
RAM interleaver
Input FIFO
Reed-Solomon decoder
Output FIFO
8-bit parallel descrambler
RAM INPUT
DEINTERLEAVER FIFO
U10
DEINTERLEAVER
ADDRESS
GENERATOR
U15
RS TIMING
CONTROLLER
RS CODEC
OUTPUT
(DECODER
FIFO
SECTION)
U16 U16
U15
Options
DEMUXDAT
8 BIT PARALLEL JP2
(SERIAL)
DESCRAMBLER
DEMUXCLK
JP2
U16 U9
A–5