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6.2.1.4.6
Appendix K. V
MODULATION (ACM) OPTION
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
Rx Descrambler = IESS (Normal,IESS,Off)
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 = EDMAC/2/3 and Reed-Solomon is OFF, its frame synchronous
scrambler is used.
•
ITU V.35 scrambler (Intelsat variant) is the default scrambler when all of the above
settings are OFF.
When you select IESS, the default ITU V.35 scrambler specified in IESS-315 takes priority over
all "normal" scramblers and is used instead. Therefore, for many operating modes, the two
scrambler selections are redundant.
Front Panel Operation
CONFIG: Rx Symb (IP-ACM or V2-ACM Modes Only)
®
FEC
/ V
ERSA
ERSA
CONFIG: Rx Descram (Descrambler)
IESS-315 V.35 Scrambler
CDM-425 Advanced Satellite Modem
FEC-2 ACM ADAPTIVE CODING
6–29
Revision 0
AND
()
MN-CDM-425
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