Comtech EF Data CDM-425, Installation And Operation Manual

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CDM-425 Advanced Satellite Modem
Revision 0
Front Panel Operation 6–40 MN-CDM-425
6.2.1.7.2 CONFIG: ACM

Unlock-Action
If using IP-ACM Mode:
When distant-end demod loses lock:
Go to min Tx ModCod (Maintain,Min) (

)
Use this submenu to establish the desired action when the remote demod loses lock. This is
important,
as the ACM system depends on the feedback of the SNR metric from the remote
demod to determine the optimum ModCod. Use the
▲▼ arrow keys to select
Go to min Tx
ModCod (recommended) or Maintain Tx ModCod . Press ENTER .
If using V2-ACM Mode:
When distant-end demod loses lock:
Go to Tx ModCod 0 (Fixed in VEFC-2)
This screen is read-only . Press ENTER or CLEAR to return to the previous menu.
6.2.1.7.3 CONFIG: ACM

Target-SNR-Margin
Target SNR Margin = 1.0 dB (0.0 – 4.5)
(

)
Use the
▲▼ arrow keys to select a margin value from
0.0 to 4.5 dB, in 0.5 dB increments. Press
ENTER .
The ACM system is designed to switch based on thresholds that correspond to
a BER of 5 x 10
-8
for each ModCod. However, in order to prevent oscillation
around two ModCods at this exact value, 0.3 dB of hysteresis has been added.