Comtech EF Data C5 - Manual (Page 140)

Operation C5/K1/K3 Integrated Satellite Terminal System
4–14 Rev. 0
RF LOOPBACK Tunes the RX frequency to the satellite downlink frequency for the
configured TX frequency.
A C-Band frequency will tune the RX frequency to 2.225 GHz below
the TX frequency.
A Ku-Band frequency will tune the RX frequency 2.3 GHz below the
TX frequency.
Note: The TX and RX data rates must be the same for the modem to
lock.
IF LOOP BACK
(Test Mode Configuration)
Programs the modem for IF loopback operation.
When IF loopback is turned on, the demodulator input is connected to
the modulator output through an internal attenuator. The demodulator
is programmed to the same frequency as the modulator. An attenuator
within the modem connects the IF Out to the IF In. When IF
loopback is turned off, the demodulator is tuned to the previous
frequency and is reconnected to the IF input. Refer to Figure 4-21 for
a block diagram of IF loopback operation.
Note: IF loopback nullifies RF loopback.
Upon entry, the status of IF loopback is displayed. Press [
$] or [%] to
make the selection. Press [ENTER] to execute the change.
BER THRESHOLD Sets the BER threshold.
If the BER threshold set is exceeded, a receive fault will be indicated
by the modem status indicators. BER threshold may be set from
1.0 E-3 to 1.0 E-8, or may be disabled by specifying NONE.
Upon entry, the current setting of the BER threshold is displayed.
Press [
$] or [%] to select the desired setting. Press [ENTER] to
execute the change.
SWEEP CENTER Programs the sweep center frequency for the directed sweep function.
When in directed sweep, the value from the sweep monitor screen
(when the modem was last lock) should be entered for the sweep
center frequency.
The sweep center frequency can be set in the range from
-35,000 to +35,000 Hz.
Upon entry, the current setting of the BER threshold is displayed.
Press [
$] or [%] to select the desired setting. Press [ENTER] to
execute the change.
SWEEP RANGE Programs the overall travel of the sweep width range during
acquisition in the directed sweep mode. The sweep width may be set
from 0 to 70000 Hz. When set at 70000 Hz, the modem is in the
normal acquisition mode. The smaller the range, the faster the modem
will lock, provided the receive carrier center frequency is within the
RX IF frequency sweep range.
Upon entry, the current programmed setting is displayed. Press [
"]
or [
#] to move the flashing cursor. Press [$] or [%] to increment or
decrement the digit at the flashing cursor. Press [ENTER] to execute
the change.