Comtech EF Data CDM-425, Installation And Operation Manual

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CDM-425 Advanced Satellite Modem
Revision 0
Front Panel Operation 6–29 MN-CDM-425
6.2.1.4.6 CONFIG: Rx

Symb (IP-ACM or V2-ACM Modes Only)
Appendix K. V
ERSA
FEC
®
/ V
ERSA
FEC-2 ACM ADAPTIVE CODING
AND
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 – S et 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 = 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.