CDM-625A Advanced Satellite Modem MN-CDM625A
Appendix P Revision 4
P–2
P.2.1 IBS Clock/Data Recovery and De-jitter
This feature performs clock and data recovery on the G.703 format. Clock de-jitter and data
encoding/decoding is done as with the IDR configuration.
P.2.2 IBS Framing
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.
P.2.3 IBS Engineering Service Channel
The IBS Engineering Service Channel provides 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.
P.2.4 IBS Scrambling
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.
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