Comtech EF Data CDM-840 - Manual (Page 99)

CDM-840 Remote Router Revision 2
Ethernet-based Remote Product Management MN-CDM840
6–31
If an CDM-840 Remote Router reports that its demod is unlocked, the ACM
Controller will assign the lowest MODCOD (QPSK ¼) to that remote in an
effort to “recover” the remote. Once the remote locks again, the ACM
algorithm adapts to the correct MODCOD for the reported Rx Es/No.
• A packet path is required from the CDM-840 to the CTOG-250 Management interface.
Rx ACM Configuration
• Rx Max MODCOD – Use the drop-down list to select the maximum demodulation type and
FEC rate (MODCOD). The available selections are:
• QPSK 1/4 • QPSK 1/3 • QPSK 2/5 • QPSK ½
• QPSK 3/5 • QPSK 2/3 • QPSK 3/4 • QPSK 4/5
• QPSK 5/6 • 8PSK 3/5 • 8PSK 2/3 • 8PSK 3/4
• 16APSK 2/3 • 16APSK 3/4 • 16APSK 5/6 • 16APSK 9/10
• 32APSK 3/4 • 32APSK 4/5 • 32APSK 5/6 • 32APSK 9/10
• Rx Target Es/No Margin – Use the drop-down list to select a margin value, in 0.5 dB
increments, from 0.0 to 4.5 dB.
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.
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Rx ACM Status (read-only)
Information is presented in this section as follows:
• Rx ACM Enable – Identifies ACM operation as Enabled or Disabled.
• Time Since Last Controller Announcement – Amount of time in seconds since the the
CDM-840 received an announcement message from the CTOG-250.
• Max Time Since Last Controller Announcement – Maximum amount of time since last
announcement message was received from the CTOG-250.
• ACM/VCM Controller IP Address – The assigned IP Address for the Controller. This will be
the management IP address for the associated CTOG-250.