Q-Flex Satellite Modem Installation and Operating Handbook
6-51
Off
When using DVB-S2, this switches ACM off in both transmit and receive.
On
This switches ACM on in both transmit and receive.
When ACM is on, the choice of modulation and FEC rate (modcod) in the
transmit path is dynamically matched to the reported Es/No from the
remote modem. Symbol rate and carrier power are unchanged but data
rate will vary with the choice of modcod.
The modem will automatically insert regular Es/No information into the
return carrier (with no material effect on bandwidth). This is used to
control the carrier modcod selection of the other modem, should it have
ACM enabled.
Monitor
This switches ACM on in receive only. This causes the modem to
automatically insert regular Es/No information into the return carrier,
which is used by the distant modem to determine the choice of transmit
modcod.
A secondary function that is switched on is as a test mode that simulates
ACM being on but does not actually change modcod. Instead, it records
what modcods
would
have been selected if ACM was actually on,
including recording the time, remote Es/No and the data rate. This allows
ACM to be tested in a non-intrusive way on a live link and also allows any
projected bandwidth savings to be confirmed prior to going live.
The record of ACM modcod changes can be viewed graphically on the
ACM graph (under
View->Graphs->IP->ACM
) or as text in the system log
(under
View->Log
).
Table 6-53 ACM Mode