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P300H P300 Series Modem Installation and Operating Handbook Page 69
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 144
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.