Tx: Code - Comtech EF Data CDM-700 Installation And Operation Manual

CDM-700 High Speed Satellite Modem
Front Panel Operation
If Tx Modulation
Tx Spectrum:
Inverted
When Normal is selected the spectral sense of the carrier has the default transition to I and Q
constellation points. Selecting Inverted causes the I and Q transition points to move in the
opposite sense. The selection of the Inverted also can correct for spectral inversion in the uplink
or downlink.
Select Normal or Invert using the ◄ ► arrow keys. Press
If Tx Modulation
Tx (α) Rolloff %:
The Rolloff, or α, dictates how fast the spectral edges of the carrier are attenuated beyond the
3dB bandwidth. The default setting is 25%; with 25% rolloff, the edge falls off more quickly
than with the 35% setting.
Select the Rolloff (α) setting using the ◄ ► arrow keys. Whenever the Mode is changed, (α)
reverts to 25%, but (α) can be modified to 35% from this menu. Press
Tx: Code
Tx Code Rate: 3/4
Refer to data rate menu for valid code rates.
• All possible choices are presented at all times.
• If an option is not installed (either Hardware or FAST) or is not valid, or if a
IMPORTANT
Select the code rate by using the ◄ ► arrow keys. Press
Tx Code Rate Selection
3/4
7/8
Inv is selected:
α is selected:
( E)
(
code rate is not available for the Mode selected, the ◄ ► arrow keys will
force the cursor to skip past the unavailable choice.
Normal
( E)
ENTER
25 35
7/8
E)
ENTER
Description
Valid for all Modulation Types
Valid for all Modulation Types (actual 20/23)
6–13
MN/CDM700.IOM
.
.
ENTER
.
Revision 5