31
LDM-144LR
NOTE
Activation of ANA loopback via the appropriate pin on the digital
interface is not available when using X.21 interface.
2. Verify that the data terminal equipment is operating properly and can be
used for a test. Do not perform tests with faulty equipment. Before
performing a test, either have the equipment repaired or replace it with a
functioning unit.
3. Execute the test with one of the methods described below:
• Using the DTE and checking the echoed data stream.
• Using an external Bit Error Rate Tester (BERT) unit.
4. Perform Step 3 above at both ends. If the BERT test indicates correct
operation, but the data terminal indicates a fault, follow the
manufacturer’s test procedures for the data terminal and verify the cable
connection between the terminal and the LDM-144LR. After completion
of the test (or when the fault has been corrected), de-activate the ANA
loopback test.
Figure 5-1. Local LDM-144LR in Analog Loopback.
DATA
TERMINAL
DATA
ANA pressed
DATA
XMTR
LINE
RCVR
CLK
CLK
Z
0
Z
I
