GDC21D003 Datasheet, PDF (59/77 Pages) Hynix Semiconductor – VSB Receiver

GDC21D003
6.6 Channel Decoder
Channel Decoder consists of Cable Slicer, Viterbi
Decoder,
Symbol-to-Byte
Converter,
Convolutional Deinterleaver, Reed-Solomon
Decoder, Data Derandomizer, Transport
Demultiplexer Interface, and etc. as shown in
Figure 6.6.1. Channel Decoder input comes from
Phase Tracker. MMDS 2/4/8/16 VSB signal and
ATSC 16 VSB signal are sliced in Cable Slicer,
and ATSC 8 VSB signal is decoded in Viterbi
Decoder. Viterbi Decoder is bypassed when I²C
register64[7](Viterbi_on) value is ‘0’. In this case,
signal is sliced by 4-level slicer. Symbol stream,
the output of Cable Slicer and Viterbi Decoder is
converted into Byte Stream by Symbol-to-Byte
Converter and sent to Convolutional Deinterleaver.
Convolutional Deinterleaver is bypassed when I²C
register64[6] (Deint_on) value is ‘0’. Reed-
Solomon Decoder and Data Derandomizer are
bypassed when I²C register64[5] (RSdec_on) and
I²C register64[4] (Derand_on) are set to ‘0’
respectively. I²C register values bypassing each
block are shown in Table 6.6.1.
Viterbi_on
Deint_on
RSdec_on
Derand_on
Table 6.6.1 I²C bus register64 values for sub-block bypass
Viterbi Decoder on/off selection
‘1’ : on
‘0’ : off
If this bit is set to ‘0’, hard decision decoding is performed instead of viterbi
decoding. Default value is ‘1’.
Deinterleaver on/off selection
‘1’ : on
‘0’ : off
If this bit is set to ‘0’, deinterleaver is bypassed. Default value is ‘1’.
RS Decoder on/off selection
‘1’ : on
‘0’ : off
If this bit is set to ‘0’, RS decoder is bypassed. Default value is ‘1’.
Derandomizer on/off selection
‘1’ : on
‘0’ : off
If this bit is set to ‘0’, derandomizer is bypassed. Default value is ‘1’.
Phase
Tracker _Cable
Slicer
Viterbi
Decoder
Vsbmode
Symbol-
1
to-Byte
0
Converter
Slicer
Viterbi_on
Convolutional
Deinterleaver
1 _Reed-Solomon 1
0
Decoder
0
Data
Derandomizer
Transport
Demultiplexer
I/F
1
0
Deint_on
RSdec_on
Derand_on
Figure 6.6.1 Block Diagram of Channel Decoder
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