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3.2.5.2.2
Initiate Handover
Clicking on the Initiate Handover button switches from the primary Demod to the secondary
Demod. The operator needs to select the Demod to which the switchover should occur (in
the Demod Select). This is a dynamic change that does not cause the transmit signal to be
disabled.
3.2.5.3 ACM
ACM (Adaptive Coding and Modulation) is an advanced algorithm that automatically adjusts
the modulation and coding points in response to conditions such as rain fade and/or
variations in satellite footprint power. For example, during clear sky conditions at all sites,
the downstream carrier may be operating at a highly bandwidth efficient modulation and
coding point (such as 8PSK modulation with 8/9 FEC). When heavy rain fades occur at one or
more sites, the modulation and coding automatically changes to a more robust point for the
traffic only to the faded sites. The downstream bandwidth for the non‐faded sites remains at
the highly efficient modulation and coding point. Once the fade is cleared at the faded sites,
the modulation and coding is automatically restored to the original highly efficient
modulation and coding point. The net effect of this technology is to deliver the highest
speed possible in the least amount of bandwidth during the majority of the time, and to
slightly reduce the speed to the faded sites during degraded conditions.
Enabling and configuring ACM requires two steps:
Field
ACM Properties
Es/No Report Interval
ModCod Timeout
3‐24
Figure 28: Set Power Transmit Level Okay Message
1. From the Configuration tab, select ACM, then set MODCOD Mask Properties. ACM
Properties are generally left with their default values.
2. From the Configuration tab, select Sites and set the fields below:
a.
ACM Operation: Select Enable to enable unilateral ACM. Can be enabled
for any or all of the 32 sites.
b. Report Es/No: Select Enable to enable bilateral ACM. Can only be enabled
for one of the 32 sites.
c.
IP Address: Set this address to the control port IP address for the modem
to which the ACM report will be sent. This IP address must also be filled in
for header compression to be functional.
Table 6: ACM Algorithm Configuration Parameters
MEOLink User Manual
Definition/Configuration
Default is 0.5 sec; range is 0.03 to 2 sec.
Default is 5 sec; range is 1 to 30 sec. If no Es/No
report is received in this time period, modem
reverts to base ModCod.
Rev 002vx
1141780,
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