Comtech EF Data CDM-625A Installation And Operation Manual page 444

Advanced satellite modem (18 kbps – 25 mbps)

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CDM-625A Advanced Satellite Modem

CDM-625A ODU (Transceiver, BUC, LNB) Operation

10.3.3.1.2.2 CONFIG: Mask  LNB

LNB alarm = Active

Attach to Rx alarm = No

When using L-Band, a Low-Noise Block Down Converter (LNB) may be included in the system. It

cannot be monitored and/or controlled by the modem, except for the power supply values.

For a modem in a 1:1 redundancy setup, the fault indications must be customized for

the physical setup:

First, use the

For LNB Alarm, use the

For Attach to Rx alarm, use the

Press ENTER when done.

Two modems, two LNBs in parallel – If a fault occurs on the active modem/LNB

pair and switchover is desired, the LNB mask should be configured as Attach to

Rx alarm = Yes.

The more common redundancy setup is Two modems in parallel, one LNB – If a

fault occurs on the active modem, switchover is desired. But, if a fault occurs on

the LNB, a switchover of modems might or might not fix the problem. If

switchover should take place, the LNB mask should configured as Attach to Rx

alarm = Yes.

If the system has no redundancy and was attached to an external audio alarm,

Attach to Rx alarm = Yes would indicate that a LNB fault has occurred, as the

fault would be included in the FORM C alarms.

arrow keys to select LNB Alarm or Attach to Rx alarm. Then:

arrow keys to select Active or Masked.

(Active,Mask)

(Yes,No)()

arrow keys to select Yes or No.

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