Interleaving - Radyne DMD20 Installation And Operation Manual

DMD20/20LBST Universal Satellite Modem

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.
Type of
Service
Small IDR
(With 16/15
O/H)
IDR
(With 96
Kbps O/H)
8PSK
DVB
1. n = code length, k = information symbols and t = symbol error correcting capability.
2. Design objective.
MN-DMD20-20LBST Revision 14
Figure 3-8 Reed-Solomon Encoder Functional Block Diagram
Figure 3-9 Reed-Solomon Decoder Functional Block Diagram
Table 3-1. Reed-Solomon Codes
Data Rate R-S Code
(Kbps) (n, k, t)
64 (126, 112, 7)
128 (126, 112, 7)
256 (126, 112, 7)
384 (126, 112, 7)
512 (126, 112, 7)
768 (126, 112, 7)
1024 (126, 112, 7)
1536 (126, 112, 7)
1544 (225, 205,10)
2048 (219, 201, 9)
6312 (194, 178, 8)
8448 (194, 178, 8)
1544 (219, 201, 9)
2048 (219, 201, 9)
6312 (219, 201, 9)
8448 (219, 201, 9)
All (204, 188, 8)
Bandwidth Interleaving
1
Expansion
[ (n/k) -1 ]
0.125
0.125
0.125
0.125
0.125
0.125
0.125
0.125
0.0976
0.0896
0.0899
0.0899
0.0896
0.0896
0.0896
0.0896
0.0851
Theory of Operation
Maximum
Depth R-S Codec
Delay (ms)
4 115
4 58
4 29
4 19
4 15
4 10
4 8
4 5
4 9
4 7
4 2
4 <2
8 18
8 13
8 4
8 3
12 -
2
3–16