Loopback Features (Terrestrial & If) - Radyne DMD20 Installation And Operation Manual

DMD20/20LBST Universal Satellite Modem
3.6 Loopback Features (Terrestrial & IF)
The modem provides for a number of different loopbacks. The Loopback supported are:
IF Loopback – Tx IF port is looped back to the Rx IF port

TX Terrestrial Loopback - Tx Data port is looped back to the Rx Data port after the

interface driver/receiver. (prior to the framing unit)
TX Baseband Loopback - Tx Data port is looped back to the Rx Data port after the

interface driver/receiver. (after the fraiming unit)
RX Terrestrial Loopback - Receive Data from the satellite is looped back for

retransmission to the satellite, providing a far end loopback. (prior to the framing unit)
RX Baseband Loopback - Receive Data from the satellite is looped back for

retransmission to the satellite, providing a far end loopback. (after to framing unit)
TX/RX Terrestrial Loopback - provides both Terrestrial loopbacks simultaneously

TX/RX Baseband Loopback - provides both Baseband loopbacks simultaneously

Usage of the modems loopback capabilities in conjunction with the Ethernet
data interface can produce undersirable network loops. In order to run any
type of data test with an Ethernet interface you must utilize two modems
IMPORTANT
connected back to back. Simply using one modem and a loopback will not
produce the desired results.
MN-DMD20-20LBST Revision 14
Theory of Operation
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