Quantum and Evolution Series Installation and Operating Handbook
7-57
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
default:
Off
Description:
Controls whether the Reed-Solomon outer-FEC encoder is active.
Edit-Tx-FEC-Outer-Advanced Menu
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 s (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.
Normal RS
Service
FEC
Terrestrial Data Rate
Type
(n,k,t)
Depth
Off
x
x
x
x
x
Closed, IBS/SMS, IDR, ESC, OM73
TCM
>1544k
Intelsat
(219,201,9)
8
<=1544k
4
IDR
Other
2048k
1544k (225,205,10)
6312k
(194,178,8)
8448k
Other (126,112,7)
Closed, IBS/SMS, ESC, OM73
Other
all
(126,112,7)
Table of Reed-Solomon N, K and Interleaver Depth Values for Normal Operation
Advanced: 1:RS N
2:RS K
3:Interleave
