Paradise P300 specifications Framing & Deframing, Intelsat Reed Solomon Codec & Custom Features

Framing & Deframing

Formats	Closed Network (unframed)
	Closed Net plus ESC [Async ESC Feature] provides variable rate async
	ESC, optional synchronous scrambler above 32kbps to replace error
	multiplying V.35 scrambler, optional backward alarm facility, and optional
	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)
Poor BER performance	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).

[INTELSAT Reed Solomon Codec & Custom Features]

Format	Concatenated Reed Solomon outer codec to IESS 308/310
Code Rate	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
Processing Delay	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)
[Custom Features]	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).

P300H P300 Series Modem Installation and Operating Handbook Page 27