CDM-625 Advanced Satellite Modem
Revision 1
Open Network Operations
MN-0000036 (Ref MN/CDM625.IOM)
14.2.1
IBS Clock/data Recovery and De-jitter
Performs clock and data recovery on the G.703 format. Clock de-jitter and data encoding/decoding
is done as with the IDR configuration.
14.2.2
IBS Framing
Multiplexes/demultiplexes the primary data in compliance with the standard IESS-309 overhead
ratio of 1/15 (4 overhead bytes per 60 data bytes) and provides the rate exchanged transmit clock
to the modulator portion of the base modem.
14.2.3
IBS Engineering Service Channel
Bi-directional processing of the components of the ESC channel, including the ASYNC or SYNC
EIA-232 data channel, and fault/alarm indications.
Alternately, a high-rate ESC channel – at up to 1/20
th
of the primary data rate – is available, using
async EIA-232 format.
14.2.4
IBS Scrambling
Provides the synchronous scrambling/descrambling of the satellite-framed data specified in IESS-309.
Base modem scrambling/descrambling is disabled in this mode.
14–2
