Comtech EF Data CDM-710G, Installation And Operation Manual

Page: 94 / 246

CDM-710G High-Speed Satellite Modem Revision 1
Front Panel Operation MN-CDM710G
6–18
(CONFIG:) Rx
Æ
Dem (Demod)
Rx Demod: Type Inv Acq
α
Eq IQ-TP Pilot Scr ( E)
Select Type , Inv , Acq ,
α
, Eq, IQ-TP , Pilot , or Scr using the
W X
arrow keys, then press
ENTER
.
If Rx Demod: Æ Type is selected:
Rx Dem: QPSK 8PSK 16QAM
16APSK 32APSK (
E)
This menu is
read-only
, as the type of modulation is determined automatically. Prior to
synchronization of the Rx path, the cursor may reside in any position. After synchronization (Rx
Traffic LED is
Green ), re-access the Rx Demod: Æ Type menu to update the display – the cursor
rests under the modulation type.
Note: While 16QAM is displayed in this menu, it is
not
selectable and
not supported
in DVB-S2
mode.
If Rx Demod: Æ Inv is selected:
Rx Spectrum:RX PARAMETERS
AUTOMATICALLY SELECTED.
This menu is
read-only
, as the demodulator automatically resolves frequency inversion.
Normal or Inverted is
not
reported in the demodulation. Press
ENTER
or
CLEAR
to return to the
previous menu.
If Rx Demod: Æ Acq is selected:
Demod Acquisition Range:
+/-010 kHz
( ▲ ▼ E)
The value entered here determines the amount of frequency uncertainty the demodulator will search
over in order to find and lock to an incoming carrier.
To edit the demodulator acquisition search range value, use the
W X
arrow keys to select the digit
to be edited, then use the
ST
arrow keys to change the value of the digit. Press
ENTER
when done.
The range varies from
±
001 kHz to
±
100 kHz.
If Rx Demod: Æ
α
is selected:
RX (
α
) Rolloff %: 20 25
35 ( E)
The rolloff or α dictates how fast the spectral edges of the carrier are attenuated beyond the 3 dB
bandwidth. With 20% rolloff the edge falls off more quickly than with 25% and 35%. Select the
value using the
W X
arrow keys, then press
ENTER
.
The default Rolloff (
α
) setting is 20% ; whenever the mode is changed, (
α
) reverts to 20% but
can be modified to 25% or 35% using this menu.