Comtech EF Data SDM-2020 - Manual (Page 152)

SDM-2020 Satellite Modulator Revision 7
Data Interfaces MN/SDM2020M.IOM
12-5
Table 12-3. Specification Summary (Continued)
Physical
Size SDM-2020 plug-in module compatible.
Hot Pluggable Not required. Unit power is turned off prior to removal or insertion of the data interface.
12.1.3.1 I
NTERFACE
L
OOPBACK
M
ODE
In loopback mode, data entering the TX connector is returned after passing through the
interface. The data entering the interface at the TX input is routed all the way through the
TX path and out to the modulator at J1. All TX signals going to the modulator (TTL level
before the TTL to LVDS translator) also are outed back to the RX path in place of the
normal signals which would be coming from the demodulator.
• In a Modulator, TX data continues to enter the modulator and is TX during
loopback.
• In a Demodulator, satellite data is not routed through the SMPTE-310M
Data Interface.
12.1.3.2 I
NTERFACE
L
OOP
-T
HROUGH
M
ODE
In loop-through mode, operation is the same as in loopback mode, however, the
test mode indications are not activated.
12.1.3.3 TX
AND
RX T
ERRESTRIAL
D
ATA
I
NTERFACE
C
ONNECTOR
(J3, J4,
AND
J6)
J3, J4 SMPTE-310M RX Data Outputs, BNC female. Both outputs are active
simultaneously.
J6 SMPTE-310M TX Data Input, BNC female.
12.1.3.4 A
UXILIARY
F
UNCTION
P
ORT
The following paragraphs describe the electrical and physcial properties of the
auxiliary function port.
12.1.3.4.1 Auxiliary Interface Electrical Specification
This port provides input/output of modem-specific signals.