Paradise Datacom Quantum Installation And Operating Handbook page 86

Quantum and Evolution Series Installation and Operating Handbook
Requires Reed-Solomon SAF feature (standard in base modem). In this
mode the Reed-Solomon FEC is active and the modem automatically
chooses appropriate values for n, k and interleaver depth.
Other
Requires both the Reed-Solomon and Custom SAF features. In this mode,
the user can choose the values of n, k and interleaver depth.
Factory
Off
default:
Controls whether the Reed-Solomon outer-FEC encoder is active.
Description:
Edit-Tx-FEC-Outer-Advanced Menu
Advanced:
This menu can be selected (when user level is set to Advanced) following the setting of the
modulation type. It contains the following options:
•
RSN. This sets the Reed-Solomon codeword length, i.e. k data symbols + (n - k) parity
symbols, where (n - k)/2 symbol errors per codeword can be corrected.
•
RSK. This sets the number of data symbols per Reed-Solomon codeword (range (n -
2) to (n - 20) in steps of 2).
•
Interleave. This is used to set the Reed-Solomon interleaver depth, which controls
resilience to burst errors (larger depth gives best BER) through data dispersal at the
expense of introducing processing delay.
The table below defines normal Reed-Solomon operation.
Service
Off
Closed, IBS/SMS, IDR, Closed+ESC, OM73
IDR
Closed, IBS/SMS, Closed+ESC, OM73
Table of Reed-Solomon N, K and Interleaver Depth Values for Normal Operation
1:RS N
2:RS K
3:Interleave
FEC Terrestrial Data Rate
x
>1544k
TCM
<=1544k
2048k
1544k
Other
6312k
8448k
Other
Other all
7-57
Type
x x
(219,201,9)
(225,205,10)
Intelsat
(194,178,8)
(126,112,7)
(126,112,7)
Normal RS
(n,k,t) Depth
x x
8
4