Quantum and Evolution Series Installation and Operating Handbook
13-5
NB: When set to 10MHZ, the station reference may
replace internal reference to all internal circuitry and
reference outputs on the IF ports. The unit
automatically switches back to internal reference if
the station reference fails.
Buffer Size
Selectable in 1ms increments from 0ms to 99ms at
data rates up to 42Mbps and from 0ms to 80ms at
data rates from 42Mbps up to 55Mbps.
Automatically adjusted to slip an integer number of
terrestrial multi-frame lengths for framed rates
Buffer storage: Maximum buffer size – 256kbytes
13.5 Framing and Deframing Specifications
Parameter
Modem
Closed Network Format
Unframed, no overhead.
IBS/SMS Option Format
Intelsat IBS to IESS-309 and IESS-310 up to 10
Mbps, and Eutelsat SMS to EESS501.
IDR Option Format
Intelsat IDR to IESS-308 and IESS-310 up to 10
Mbps.
Closed Network plus
ESC Format
Provides variable rate asynchronous 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%
Poor BER Performance
Deframer includes extended threshold operation
that 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). Up
to 10 Mbps
