Comtech EF Data SDM-2020, Installation And Operation Manual

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SDM-2020 Satellite Demodulator Data Interfaces
Rev.3 A–71
A.8.4 Loopback Connection
Refer to Table A-40 for additional requirements for Loopback.
Table A-40. Looback Connections
ASI Interface is active in Modulator Loops ASI input, J3 (or J4), to ASI output, J7. If JP1 is Off,
then J3 (J4) also loops to J6, the LVDS-DVB parallel output
The LVDS signal contains D0-D7, Sync, Dvalid, and Clock
LVDS Interface is active in Modulator If J1 is On, then J6 (LVDS-DVB input) is looped to the ASI
output J7.
ASI Interface is active in Demodulator JP1 is Off (Normal): When Loopback is engaged the TX ASI
(J3) input connects simultaneously to the RX ASI (J7) and to
the RX LVDS connector (J6). The LVDS signal contains D0-
D7, Sync, Dvalid, and Clock
JP1 is On: When Loopback is engaged the TX LVDS (J6)
input connects to the RX ASI (J7) connector.
LVDS Interface is active (output) in
Demodulator JP1 is ON: When Loopback is engaged the TX LVDS (J6)
input connects to the RX ASI connector (J7). The LVDS signal
contains D0-D7, Sync, Dvalid, and Clock.
JP1 is OFF (Normal): When Loopback is engaged the TX ASI
input connects to the RX ASI connector and to the RX LVDS
connector. The LVDS signal contains D0-D7, Sync, Dvalid,
and Clock.
A.8.5 Loop Thru
The operation of Loop Thru is the same as Loopback except the normal operating mode
not a test mode, and the TEST LED does not illuminate.