Comtech EF Data SDM-100A - Manual (Page 47)

SDM-100A Satellite Modem Operation
Rev. 0 3–13
3.2.1.1.2 Configuration Demodulator
RX-X
Code_Rate/Type Receiver rate selection. One of four predefined receiver
decoder/data rate combinations (A, B, C, or D) or a variable rate
selection (V) may be selected. These selections must first be set up
in the Utility menu.
On entry, the current receiver rate is displayed with the flashing
cursor on the first character of the code rate on line 1. The data rate
is displayed on line 2. Press [
↑ ] or [ ↓ ] to select one of four predefined
rates (A, B, C, or D).
To select the variable data rate, select “RX-V” and press [ENTER]
twice to select the currently defined data rate.
To change the rate in the variable rate selection, press [ENTER]
when “RX-V” is displayed. A flashing cursor will be displayed on the
first character of the coding type on line 1. Press [
← ] or [ → ] to move
the flashing cursor. Press [ ↑ ] or [ ↓ ] to increment or decrement the
digit at the flashing cursor. Press [ENTER] to execute the change.
RX-IF Frequency Programs the receive frequency between 50 and 180 MHz, in
2.5 kHz steps.
On entry, the current receive frequency is displayed with the flashing
cursor on the first character. Press [
← ] or [ → ] to move the flashing
cursor. Press [ ↑ ] or [ ↓ ] to increment or decrement the digit at the
flashing cursor. Press [ENTER] to execute the change.
Descrambler Programs the V.35 descrambler ON or OFF.
On entry, the current status of the descrambler is displayed. Press
[
↑ ] or [ ↓ ] to select ON or OFF. Press [ENTER] to execute the change.
Diff. Decoder Programs the differential decoder ON or OFF.
On entry, the current status of the differential decoder is displayed.
Press [
↑ ] or [ ↓ ] to select ON or OFF. Press [ENTER] to execute the
change.
RF Loop Back Programs the modem for RF loopback operation (test mode).
When RF loopback is turned on, the demodulator is programmed to
the same frequency as the modulator. When RF loopback is turned
off, the demodulator is tuned to its previous frequency. Refer to
Figure 3-26 for a block diagram of RF loopback operation.
Note: RF loopback nullifies IF loopback.
On entry, the current status of RF loopback is displayed. Press [
↑ ] or
[ ↓ ] to select ON or OFF. Press [ENTER] to execute the change.