3 interleaving – Comtech EF Data DMD1050 User Manual
Page 47
DMD1050 Satellite Modem Board
Theory of Operation
MN-DMD1050
3–21
Revision 9
3.12.3 Interleaving
The DMD1050 allows for interleaving depths of 4 or 8 R-S Blocks so that burst errors are spread
over 4 or 8 R-S blocks to enhance the error correction of the R-S Codec. In Closed Network
Mode, manually set the interleaver depth to 4 or 8. In DVB Network Mode, the DMD1050 sets
the interleaver depth to 12 automatically.
Figure 3-10. Reed-Solomon Encoder Functional Block Diagram
Figure 3-11. 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.