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SDM-300L3 Satellite Modem
Revision 1
Front Panel Operation
MN/SDM300L3.IOM
4–13
FUNCTION SELECT: CONFIGURATION: MODULATOR:
CARRIER MODE
CARRIER MODE
NORMAL-MODULATED
Programs the modem for alternate carrier modes. All modes, except Normal-Modulated
are
Test Modes
. Four modes of operation are available:
NORMAL-MODULATED
This mode is normally selected.
CENTER-CW
Generates a CW-carrier at the current modulator frequency. This can be used to
measure the output frequency.
DUAL-CW
Generates a dual side-band suppressed carrier signal. Side-bands are at one-half of
the symbol rate from the carrier. This is used to check the channel balance and
carrier null.
OFFSET-CW
Generates a single, upper, side-band-suppressed carrier signal. The upper side-
band is at one-quarter of the symbol rate from the carrier. When inverted spectrum
is selected, this generates a single, lower, side-band-suppressed carrier.
Upon entry, the Center mode is displayed. To activate this test mode, press <ENTER>.
Press [
↑
] or [
↓
] to select the desired mode. To return to the Configuration menu, press
[CLEAR].
FUNCTION
SELECT:
CONFIGURATION: MODULATOR:
MODEM
REFERENCE
MODEM REFERENCE
INTERNAL
Select either: Internal, EXT1 MHz, EXT5 MHz, EXT 10MHz, EXT 20MHz, or
Output 10 MHz.
IMPORTANT
Use only Internal or EXT 10 MHz with a Block Up Converter (BUC) or
Outdoor Unit (ODU).
Upon entry, the current status of the scrambler is displayed. Press [
↑
] or [
↓
] to make the
selection. Press <ENTER> to execute the change.
Note:
If any EXT REF is selected for the modem reference and is disconnected or not
present at CP3, an alarm is generated, and the modem switches to its Internal Clock.