Comtech EF Data SDM-300A - Manual (Page 106)

SDM-300A Satellite Modem Revision 6
Front Panel Operation MN/SDM300A.IOM
5–12
FUNCTION SELECT: CONFIGURATION: MODULATOR:
DIFF. ENCODER
DIFF. ENCODER
ON
Programs the Differential Encoder: On or Off. Upon entry, the current status of the scrambler is
displayed. Press [ ↑] or [↓] to make the selection. Press [ENTER] to execute the change.
IMPORTANT
Always Off in Turbo mode.
FUNCTION SELECT: CONFIGURATION: MODULATOR:
CARRIER MODE
CARRIER MODE
NORMAL-MODULATED
Programs the modem for alternate carrier modes.
IMPORTANT
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].
Note: When [CLEAR] is pressed, the modem is configured to the state before CW mode was
invoked. The transmitter is automatically turned off to prevent the possible swamping of other
channels. To turn the transmitter on, use the IF Output function.