Operation
DMD2401 LB/ST L-Band Satellite Modem and ODU Driver
3-14
TM075 – Rev. 1.3
3.12.2 Baseband Loopback
Baseband Loopback provides the following data loopback on the baseband (or framing card) and
allows testing of the terrestrial interface of the modem:
Note: On the DMD2401, a framing card is required to properly use any of the baseband
loopback functionality.
Tx BB Loopback – Terrestrial TX data after passing through the line interface and onto
the baseband framing unit is looped back to the Rx data line drivers of the interface
(refer to Figure 3-6).
Rx BB Loopback – The Rx Data received by the satellite is passed through the
interface and looped back through baseband framing unit, then sent back through the
interface for retransmission to the satellite providing a far end loopback (refer to Figure
3-7).
Tx/Rx BB Loopback – Provides both of the above loopbacks simultaneously (refer to
Figure 3-8).
3.12.3 IF Loopback
IF Loopback loops back the modulated IF Signal from the modulator to the demodulator (refer to
Figure 3-9).
Figure 3-3. Tx Terrestrial Loopback
Figure 3-4. Rx Terrestrial Loopback
