Comtech EF Data CDD-880, Инструкция по установке и эксплуатации

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CDD-880 Multi Receiver Router MN-CDD880
Appendix G Revision 2
G–23
After the targeting of reference calibration, the DPC Delta is zeroed, and any +/- offset from this
point indicates power changes due to link quality variations.
Depending on symbol rate, small rates will have variations up to ±.5 dB, even during
clear-sky conditions.
Item Description
Current Beam offset Current Beam offset is modified in a roam configuration, and any +/- offset
from zero either adds or subtracts from the margin or terminal maximum
power backoff during a beam contour variation.
Target Es/No Target Es/No is calculated from maximum MODCOD and will remain
constant unless changed.
Last Es/No Received This most recent reported value may change depending on link conditions.
Current DPC Delta This represents the Adaptive Control Loop (ACL) change in power compared
to the set reference, which can increase to margin or terminal maximum
power. Any decrease has the full remaining range down to -40 dBm of
modulator’s output.
Time since last LQRM This is the time, in seconds, from the last power report received. Under
normal conditions, the status updates every 60 seconds.
G.4.2 DPC – Operational Changes
DPC operation modifies the behavior between VMS site policy home state parameters and
power reference control.
Normally, the operator updates the home state parameter in the VMS to match the current
settings in the CDM-840. This synchronizes the power settings between the two, providing
correct power adjustments when the VMS sends a switch command to modify transmission
rates.
When you enable DPC, you now modify power with the CDM-840 and ignore any power setting
in the switch command; this changes the behavior of the home state settings. The home state
settings remain very important for frequency domain check, but you now use the power only to
limit the site’s symbol rate. During each rate change, the VMS calculates a new power value,
comparing this value against the Up-converter’s power limit value; if the calculated power is less
than or equal to this value, the requested rate is set. However, if the calculated power is greater
than this value, the requested rate will be limited to the set limit.