Comtech EF Data SDM-100A - Manual (Page 92)

Operation SDM-100A Satellite Modem
3–58 Rev. 0
B-Band Loop Back Programs the modem for baseband loopback operation (test
mode).
When baseband loopback is turned on, the data and timing
signals are hard-wired (via relays) from the demodulator to the
modulator on the modem side of the interface. The DTE
baseband signals are also looped back from the transmitter data
and clock to the receiver data and clock on the customer side of
the interface. This is a bi-directional loopback of the baseband
data. Refer to Figure 3-28 for a block diagram of baseband
loopback operation.
On entry, the current status is displayed. Press [
↑ ] or [ ↓ ] to select
ON or OFF. Press [ENTER] to execute the change.
V.35 Scrambler Programs the scrambler ON or OFF.
On entry, the current status of the V.35 scrambler is displayed.
Press [
↑ ] or [ ↓ ] to select ON or OFF. Press [ENTER] to execute
the change.
V.35 Descrambler Programs the descrambler ON or OFF.
On entry, the current status of the V.35 descrambler is displayed.
Press [
↑ ] or [ ↓ ] to select ON or OFF. Press [ENTER] to execute
the change.
Diff. Encoder Programs the differential encoder ON or OFF.
On entry, the current status of the Differential Encoder is
displayed. Press [
↑ ] or [ ↓ ] to select ON or OFF. Press [ENTER] to
execute the change.
TX Clock Source Programs the clock source for the modem transmitter clock.
“SCT (Internal)” sets the TX clock to operate from the modem
internal clock. This is also the fallback clock.
“TX Terrestrial” sets the TX clock to recover timing from the
incoming clock/data.
On entry, the current transmit clock setting is displayed. Press
[
↑ ] or [ ↓ ] to select “SCT” or “TX Terrestrial,” clock. Press
[ENTER] to execute the change.
RX Clock Phase Programs the RX clock phase to “Normal” or “Inverted.”
On entry, the current status of the RX Clock is displayed. Press
[
↑ ] or [ ↓ ] to select “Normal” or “Invert.” Press [ENTER] to
execute the change.