P300H
P300 Modem Installation and Operating Handbook
Page 67
Tx RS outer codec: [?]
1=Off 2=INTELSAT n,k,t & depth 3=Other
Change, Tx/Rx, Mod/Demod, Reed-Solomon Menu
Scrambler: [?]
1=Off 2=Normal 3:Other
Change, Tx/Rx, Mod/Demod, Scrambler Menu
The Reed-Solomon menu appears as follows:
The Reed-Solomon outer FEC codec may be configured as follows:
OFF
The Reed-Solomon out FEC is disabled. Note that for testing the effectiveness
of the RS codec, a test mode allows you to disable the RS decoder error
corrections without removing the RS overhead (which changes the satellite data
rate and therefore to a small extent the Rx Eb/No).
INTELSAT
This switches the RS codec on using standard INTELSAT values which are as
follows:
FEC
Framing
Data Rate
(n,k,t)
Depth
TCM
Any
> 1544 kbps
8
(219,201,9)
<= 1544 kbps
4
Non-TCM
eg Turbo, Viterbi,
Sequential, or
No FEC
IDR
1544 kbps
(225,205,10)
2048 kbps
Other rates
(126,112,7)
IBS or
All rates
Closed Net
Note: When interworking with NEC modems in TCM mode (and IBS framing), NEC have chosen to use
Interleaving depth 4 for all data rates. For rates >1544kbps then it will be necessary to select `Other`,
and manually select the interleaving as depth 4.
OTHER
This option is only available if the `Custom Features` feature is available
(standard on P300-TCM). This feature allows the operator to specify the code
rate outside of the normal INTELSAT parameters
ie a fully variable code rate
Reed-Solomon codec
. The limitations are as follows `n` = [60 - 255], `k` = [n -
(2, 4, 6, 8, 10, 12, 14, 16, 18, or 20)] ie `t`=1 to 10.
See the applications section, para 8.4 "Choosing
Optimum
Custom RS N&k
Values" on page 134
6.6.13 Change, Tx/Rx, Mod/Demod, SCRAMBLER Menu
The Scrambler selection is made from
OFF
,
NORMAL
, and
CUSTOM
.
OFF
Turns off all scrambling, and whilst this may be used for testing or carrier line up,
it is not normally used over satellite.