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Figure A-21. Reed-Solomon Encoder Section Block Diagram
A.3.3
Interleaver
The interleaver is implemented by writing scrambled and RS encoded data (with check
bytes) into a static ram in a row format, and reading data out in a column format.
The interleaver depth can be programmed for 4, 8, or 16.
When a depth of 4 is programmed, the interleaver consists of four pages with each page
consisting of 4 Reed-Solomon code word blocks. A total of 16 Reed-Solomon code
word blocks make up the interleave frame. The unique words are inserted during the
interleaving process and placed in the last two bytes of the last two Reed-Solomon code
word blocks of the last page of the interleave frame.
When a depth of 8 is programmed, the interleaver consists of two pages with each page
consisting of 8 Reed-Solomon code word blocks. Again, a total of 16 Reed-Solomon
code word blocks make up the interleave frame. The unique words are inserted during
the interleaving process and placed in the last two bytes of the last two Reed-Solomon
code word blocks of the last page of the interleave frame.
The unique word is used by the decoder to detect the frame boundary for
synchronization of the descrambler and the deinterleaver. The deinterleaver operates in
much the same manner as the interleaver, except it writes data in column format and
reads in row format. See Figure A-22. for the RS code word format prior to
interleaving.
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A–74
Revision 3
MN/SLM3650.IOM
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