DMD20/20LBST Universal Satellite Modem
Theory of Operation
MN-DMD20-20LBST Revision 14
3–16
3.9.3 Interleaving
Interleaving depths of 4, 8, or 12 R-S blocks are allowed. This allows burst errors to be spread
over multiple blocks in order to enhance the error correcting performance of the R-S Codec. For
Intelsat Network Modes, the interleaving depth is automatically set to 4 for QPSK or BPSK, or 8
for 8PSK. In Closed Network Mode, the interleaver depth can be manually set to 4 or 8, and in
DVB Network Mode, the interleaver depth is automatically set to 12.
Figure 3-8 Reed-Solomon Encoder Functional Block Diagram
Figure 3-9 Reed-Solomon Decoder Functional Block Diagram
Table 3-1. Reed-Solomon Codes
Type of
Service
Data Rate
(Kbps)
R-S Code
(n, k, t)
1
Bandwidth
Expansion
[ (n/k) -1 ]
Interleaving
Depth
Maximum
2
R-S Codec
Delay (ms)
Small IDR
(With 16/15
O/H)
64
128
256
384
512
768
1024
1536
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
(126, 112, 7)
0.125
0.125
0.125
0.125
0.125
0.125
0.125
0.125
4
4
4
4
4
4
4
4
115
58
29
19
15
10
8
5
IDR
(With 96
Kbps O/H)
1544
2048
6312
8448
(225, 205,10)
(219, 201, 9)
(194, 178, 8)
(194, 178, 8)
0.0976
0.0896
0.0899
0.0899
4
4
4
4
9
7
2
<2
8PSK
1544
2048
6312
8448
(219, 201, 9)
(219, 201, 9)
(219, 201, 9)
(219, 201, 9)
0.0896
0.0896
0.0896
0.0896
8
8
8
8
18
13
4
3
DVB
All
(204, 188, 8)
0.0851
12
-
1. n = code length, k = information symbols and t = symbol error correcting capability.
2. Design objective.