Paradise Datacom P300-VSAT Installation & Operating Handbook page 27

Poor BER performance
[INTELSAT Reed Solomon Codec & Custom Features]
Format
Code Rate
Processing Delay
[Custom Features]
[Drop /Insert Feature]
Bearer Types
P300H
Timeslot ID Maintenance when used with Drop/Insert, all in minimum
possible overhead down to <0.5%.
INTELSAT IBS & Eutelsat SMS [IBS/SMS Feature]. Framing to IESS 309
& IESS 310
INTELSAT IDR [IDR Option]. Framing to IESS 308 & IESS 310
Custom Framing [`Custom Features` feature]. Provides custom framing
based on IBS or IDR formats. For example the use of 16 kbps ADPCM
on the IDR audio ESC channels, providing an IDR carrier with all normal
facilities but with 32kbps of overhead spare for continuous traffic quality
BER monitoring (using built in PRBS tester with automatic results logging
or external BERT)
Deframer includes extended threshold operation which improves
performance when used with Reed-Solomon in very poor BER
conditions (where a single uncorrectable RS codeword can contain
enough corrupt frame alignment words to knock an INTELSAT specified
deframer out of frame sync).
Concatenated Reed Solomon outer codec to IESS 308/310
Default n, k, t = (126, 112, 7) depth 4, automatically switching to: (225,
205, 10) depth 4 for 1544 kbps IDR mode. (219, 201, 9) depth 4 for 2048
kbps IDR mode & TCM <=1544 kbps, and (219, 201, 9) depth 8 for TCM
>1544 kbps
Combined Encoder & Decoder: 8 x (2n - k + 60)
Combined Interleaver & De-interleaver: 8 x n x depth (Calculate delay
time using data rate including RS overhead)
When available allows arbitrary selection of `n` & `k` to provide fully
variable code rate.
`n` = 60-255
`k` = n-2 to n-20 step 2
Interleaving depth of four or eight
The `Custom Features` Feature allows use of shorter codewords to
reduce interleaver / de-interleaver delay on low data rate circuits. For
example switching from n, k, t = 126, 112, 7 to 64, 56, 4 provides
approximately the same correction ability (7 in 126 = 5.5% and 4 in 64
= 6.25% respectively), with similar overheads (126/112=12.5%,
64/56=14.3%), but with interleaving & decoder delays reduced from 5632
to 3104 bits (156 ms to 85 ms at 32 kbps).
T1-D4, T1-ESF, and G.732.
P300 Modem Installation and Operating Handbook Page 27