Datum Systems M7 Series - Figure 1-19 - Reed-Solomon Block Diagram; Table 1-4 - Reed-Solomon Modes

Operation M7/M7L/M7LT Modular Satellite Modem
1-24 M7/M7L/M7LT - Rev. 0.05
Transmit Reed-Solomon
Block Encoder &
Synchronous Scrambler
Processor
Transmit
Terrestrial Data
Channel
Receive
Terrestrial Data
Channel
Transmit
Data Channel
Receive Data
Channel
Control
XMT
Clock and Frame
Generation
RCV
Control
Clock
Clock
Main Modem
Assembly
Clocks
Reed-Solomon Codec Simplified Block Diagram
Transmit Reed-Solomon
Block Interleaver
Receive Reed-Solomon
Block Decoder &
Synchronous
Descrambler
Receive Reed-Solomon
Block De-Interleaver
FIFO From
Main Modem
IBS
Multiplex
Option
Figure 1-19 - Reed-Solomon Block Diagram
The available Reed-Solomon modes shown in Table 1-4 can be selected from the front panel or
remote control. The CT220,200 mode is a special compatibility mode and is automatically set by
certain CT FEC modes, for example when Viterbi, Rate 3/4 is selected when in 16QAM mode. It can
be over-ridden from the Custom Reed-Solomon parameter settings.
Table 1-4 - Reed-Solomon Modes
Mode
Compatibility
Terrestrial Data
Rate
Overhead
Ratio
n, k and depth Values
Disabled
N/A
1/1
IESS-308
IESS-308
1.2 kbps to
<1.544 Mbps
9/8
126, 112, 4 (M4 modem compatible)
IESS-308
1.544 Mbps to
<2.048 Mbps
45/41
225, 205, 4
IESS-308
>2.048 Mbps
73/67
219, 201, 4
IESS-309
IESS-309
All
73/67
219, 201, 4
CT220,200
Comtech
All
11/10
220, 200, 4
Custom
Modified IESS-
309
All
Variable
Allows setting the “n”, “k” and “depth”
values for special requirements. Can
also be set for M4 compatibility to max
M4 data rate.