Comtech EF Data SDM-309B - Manual (Page 59)

Operation SDM-309B Satellite Modem
3–28 MN/U-SDM309B Rev. #
CW_Mode *Programs the modem for continuous wave mode. Three modes of
operation are available: center, dual, and offset modes.
Center Mode:
Generates a carrier at the current modulator frequency. This can
be used to measure the output power and output frequency.
Dual Mode:
Generates a dual side-band suppressed carrier signal. Side-bands
are at one half (1/2) the symbol rate from the carrier. This is used
to check the channel balance and carrier null.
Offset Mode:
Generates a single upper side-band suppressed carrier signal.
The upper side-band is at one quarter (1/4) the symbol rate from
the carrier. This is used to check the quadrature.
On entry the “CENTER” mode is displayed. To activate this test
mode press the “ENTER” key. Use the arrow keys to select the
“DUAL or the “OFFSET” modes. To return to the “CONFIG” menu
press the “CLEAR” key.
Note: When the “CLEAR” key is pressed, the modem is
configured to the state it was in before “CWMode” was invoked
and the transmitter is automatically turned off to prevent the
possible swamping of other channels. To turn the transmitter on
use the “RF_OUT” function.
3.2.2.2 DEMOD Configuration
RXA Receiver rate selection. Select one of four predefined receiver
decoder/data rate combinations or a variable rate selection.
On entry the current receiver rate is displayed with the flashing cursor on
the first character of the code rate on line one. The data rate is displayed
on line two. Use the arrow keys to select one of four predefined rates.
Filters that are not present may display as “N/A” (not assigned) and can
not be programmed. If your modem is equipped with the variable rate
option you can also select TXV and enter the desired data rate.
RX_freq Programs the demodulator receive frequency between 50 and 90 MHz or
110 and 180 MHz in 2.5 KHz Steps.
On entry the current receive frequency is displayed with the flashing
cursor on the first character. Use the right and left arrow keys to move
the flashing cursor and the up and down arrow keys to increment or
decrement the digit at the flashing cursor. Press the “ENTER” key
execute the change.
Note: The receiver frequency is programmable within the specified
range (50 - 90 MHz or 110 - 180 MHz) in 2.5 KHz Steps.
DifDecdr Programs the differential decoder On or Off.
On entry the current status of the differential decoder is displayed with
the flashing cursor on the first character. Use the arrow keys to select ON
or OFF. Press the “ENTER” key to execute the change.