Comtech EF Data DD2401 VME - Manual (Page 24)

Theory of Operation DD2401 VME L-Band Demodulator Card Installation & Operational Manual
3-6 MN-VME2401 – Rev. B
3.2.4 Interleaving
The DD2401 VME DEMODULATOR CARD allows for interleaving depths of 4 or 8 R-S blocks.
This allows burst errors to be spread over 4 or 8 R-S blocks in order to enhance the error
correcting performance of the R-S Codec.
Figure 3-4. Reed Solomon Decoder Functional Block Diagram
Table 3-1. Reed-Solomon Codes for IDR
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
(225, 205,10)
(219, 201, 9)
0.0976
0.0896
4
4
9
7
n = code length, k = information symbols and t = symbol error correcting capability.
Design objective
For the DD2401 VME Demodulator Card, the IDR Deframing must be supplied externally.