CDM-625A Advanced Satellite Modem MN-CDM625A
Front Panel Operation Revision 4
6–29
6.2.1.4.6 CONFIG: Rx Symb (IP-ACM or V2-ACM Modes Only)
Appendix M. ADAPTIVE CODING AND MODULATION (ACM)
VersaFEC ACM or VersaFEC-2 ACM modes require the appropriate FAST codes for
the maximum operating symbol rate.
RxSymbolRate = 01000.000 ksps (ACM Mode)
Data Invert=Off Clock Invert=Off ()
When either ACM mode is active, the CONFIG: Rx menu changes the Data option to Symb.
On the top line – Edit the Rx Symbol Rate by using the
◄ ►arrow keys to select a digit, and
then using the
▲▼ arrow keys to change that digit. Press ENTER. Note that asymmetric
operation is supported – transmit and receive symbol rates do not have to be equal.
On the bottom line – Set the Data Invert or Clock Invert operation by using the
▲▼ arrow keys
to select On or Off. Press ENTER.
6.2.1.4.7 CONFIG: Rx Descram (Descrambler)
Rx Descrambler = IESS (Normal,IESS,Off)
IESS-315 V.35 Scrambler ()
Use the
▲▼ arrow keys to select Normal, IESS, or Off. Press ENTER.
The modem automatically selects the actual scrambler used for Normal, depending on the exact
operating mode:
• When framing = IBS/D&I, the IESS-309 scrambler is used.
• When Reed-Solomon is ON but IBS/D&I is OFF, its frame synchronous scrambler is used per
IESS-310, App. H. An exception to this is legacy Comtech EF Data Reed-Solomon, which
instead uses a proprietary modified V.35 scrambler.
• When framing = EDMAC/2/3 and Reed-Solomon is OFF, its frame synchronous scrambler is
used.
• When configured for TPC (Turbo) encoding and all of the above settings are OFF, the TPC
frame scrambler is used except for 8-QAM. For CDM-570 compatibility, TPC with 8-QAM
uses the V.35 scrambler.
• ITU V.35 scrambler (Intelsat variant) is the default scrambler when all of the above settings
are OFF.
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