User guide

Introduction
C-2 Vipersat CDD-56X Series User Guide
control algorithm is a closed loop servo-mechanism with the received E
b
/N
o
values as the input function and the modulator’s transmit power as the output
function. Only modulator transmit power is controlled by the algorithm since
the receive chain has its own automatic gain control. DPC can be applied to any
or all of the modems with the exception of the STDMA burst control demodula-
tors. Since the STDMA burst demodulators are SCPC fast acquisitions receivers
they cannot provide stable signal quality measurements (E
b
/N
o
). This value is
critical in closing the power loop control mechanism.
Note: STDMA is not susceptible to bursts at different power levels since it is a
standard SCPC demodulator — as long as the input C/N burst power
ranges comply with the performance specifications of the modem. An
example is an operation using meshed video carriers.
DPC is a modulator function that cannot be enabled in remotes operating in
STDMA mode. DPC is automatically turned on when the remote switches to
SCPC mode.
NOTE