Comtech EF Data CDM-625A - CONFIG: Tx  Freq (Frequency)

CDM-625A Advanced Satellite Modem MN-CDM625A
Front Panel Operation Revision 4
6–13
• Txα (Tx Alpha Filter Rolloff Factor) – Use the ▲▼ arrow keys to select the Txα. Press
ENTER. Valid settings are:
Txα (Tx Alpha rollout Factor) (%)
Default
0.05, 0.10, 0.15, 0.25
0.35
The Rxα of the corresponding receiver must match the Txα – see Sect. 6.2.1.4.1
for details. To summarize:
• Set Rxα = 0.35 if Txα ≥ 0.25;
• Set Rxα = 0.12 if Txα ≤ 0.20.
6.2.1.3.2 CONFIG: Tx  Freq (Frequency)
Tx-IF Frequency: 0050.0000 MHz
()
To edit the Tx-IF Frequency, use the
◄ ►arrow keys to select a digit, and then use the ▲▼
arrow keys to change that digit. Press ENTER. Valid settings are:
IF Frequency
Range
Step Size (Increment)
70/140 MHz
50-180 MHz
100 Hz
L-Band (FAST Option)
950-2250 MHz
100 Hz
When you use the ODU menus to configure a BUC lockout frequency, this screen displays a
second line of information:
Tx-IF Frequency: 1750.0000 MHz
(LO:12500 MHz Sat:14250.0000 MHz) ()
As you edit the IF frequency, the Satellite frequency updates accordingly.
Satellite frequency = LO ± IF frequency
, where the sign ± is determined
by the LO mix parameter:
• High-sided mix [–] (includes a spectral inversion);
•
Low-sided mix [+].