DMD1050TS Satellite Modem Board
Revision 1
Theory of Operation 3–17 MN-DMD1050TS
3.8 Internal Clock
The time and date are used to time-stamp system events. You can change the time and date via
the Web Browser.
3.9 Loopback Features (Terrestrial & IF)
CAUTION: DATA LOSS POSSIBLE
To run any type of data test with an Ethernet interface, you must use two
modems connected back-to-back. Using the modem’s loopback with the
Ethernet data interface causes unwanted network loops and useless results.
The modem allows for several different loopbacks:
• 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 framing 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 the framing unit)
• Tx/Rx Terrestrial Loopback - provides both Terrestrial loopbacks simultaneously
• Tx/Rx Baseband Loopback - provides both Baseband loopbacks simultaneously
See Figure 3-7 through Figure 3-9 for loopback functional block diagrams.
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