3.2.4.9.2. RSC DB Decoder parameters¶
3.2.4.9.2.1. --dec-type, -D
¶
Type: text Allowed values: BCJR
CHASE
ML
Default: BCJR
Examples: --dec-type BCJR
Select the decoder type.
Description of the allowed values:
Value | Description |
---|---|
BCJR |
Select the BCJR DB decoder [BCJR74]. |
CHASE |
See the common --dec-type, -D parameter. |
ML |
See the common --dec-type, -D parameter. |
3.2.4.9.2.2. --dec-implem
¶
Type: text Allowed values: GENERIC
DVB-RCS1
DVB-RCS2
Default: DVB-RCS1
Examples: --dec-implem DVB-RCS1
Select the implementation of the algorithm to decode.
Description of the allowed values:
Value | Description |
---|---|
GENERIC |
Select a generic implementation that works on any trellis. |
DVB-RCS1 |
Select an implementation dedicated to the DVB-RCS1 trellis
(faster than the GENERIC implementation). |
DVB-RCS2 |
Select an implementation dedicated to the DVB-RCS2 trellis
(faster than the GENERIC implementation). |
3.2.4.9.2.3. --dec-max
¶
Type: text Allowed values: MAXS
MAXL
MAX
Examples: --dec-max MAX
Select the approximation of the \(\max^*\) operator used in the trellis decoding.
Description of the allowed values:
Value | Description |
---|---|
MAXS |
\(\max^*(a,b) = \max(a,b) + \log(1 + \exp(-|a - b|))\). |
MAXL |
\(\max^*(a,b) \approx \max(a,b) + \max(0, 0.301 - (0.5 |a - b|))\). |
MAX |
\(\max^*(a,b) \approx \max(a,b)\). |
MAXS
for Max Star is the exact \(\max^*\) operator. MAXL
for
Max Linear is a linear approximation of the \(\max^*\) function. MAX
for Max is the simplest \(\max^*\) approximation with only a
\(\max\) function.
Note
The BCJR with the \(\max\) approximation is also called the max-log-MAP algorithm.
3.2.4.9.2.4. References¶
[BCJR74] | L. Bahl, J. Cocke, F. Jelinek, and J. Raviv. Optimal decoding of linear codes for minimizing symbol error rate (corresp.). IEEE Transactions on Information Theory (TIT), 20(2):284–287, March 1974. doi:10.1109/TIT.1974.1055186. |