5.3 LOOPBACK TEST (LAL)
The Model 2703RC-A is equipped with a Local Analog Loopback
(LAL) mode to assist in evaluating the operation of the local Model
2703RC-A. Any data sent to the local Model 2703RC-A in this test
mode will be echoed (returned) back to the user device. For example,
characters typed on the keyboard of a terminal will appear on the ter-
minal screen.
To perform a LAL test, follow these steps:
A.
Activate LAL by moving the front panel toggle switch UP and
holding it in the “Loopback” mode. The “Loop” LED should
glow. Once LAL is activated, the Model 2703RC-A transmit
output is connected to its own receiver. (Note: The front
panel switch is spring loaded, so it will return to “Normal”
operating mode when pressure is released.)
B.
Verify that the data terminal equipment is operating properly
and can be used for a test. If a fault is indicated, call a
technician or replace the unit.
C. Perform a BER (bit error rate) test on each unit. If the BER
test equipment indicates no faults, but the data terminal indi
cates a fault, follow the manufacturer’s checkout procedures
for the data terminal. Also, check the interface cable between
the terminal and the Model 2703RC-A.
17
A
APPPPEEN
ND
DIIX
X
A
A
MODEL 2703RC-A SPECIFICATIONS
Network Interface:
G.703
Network Rate:
2.048 Mbps
Network Connectors:
Two BNC (75 Ohm) or one modu-
lar RJ-45 connector (120 Ohm)
Terminal Interface:
EIA-530 (RS-422), V.35, or X.21
on DB-25 female or ITU/CCITT
X.21 on DB-15 female
Internal Interface:
Connection to Model 1000R16
rack chassis via 50 pin male card
edge
Terminal Rate:
256, 512, 1024, 2048 kbps
Diagnostics:
Loopback Test
Indicators:
LEDs for power, network, master
clock and loopback test
Clocking:
Master Internal , Slave (Recovered
from the G.703 Network)
Receiver Sensitivity:
-10 dB (0dB = 2.4V Peak)
Temperature Range:
0-60°C (32-140°F)
Altitude:
0-15,000 feet
Humidity:
5 to 95% noncondensing
Front Card Dimensions:
0.95”W x 3.1”H x 5.4”L
Rear Card Dimensions:
0.95”W x 3.1”H x 2.8”L
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