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SYNC/ASYNC FIBER OPTIC MODEM
• Communication Link: determines the performance of both the local and
remote Fiber Optic Modems and of the link between them.
Tests are activated by pushbuttons and monitored via LED indicators on the
front panel of Fiber Optic Modem. For a description of the Fiber Optic Modem’s
controls and indicators and their functions, see
Chapter 4
.
5.2 Loopback Tests
Loopback tests are best performed in the order presented in this section.
NOTE
Before running the loopback tests:
• Verify that the DTE is operating properly and can be used for the test.
Do not run any tests using faulty equipment.
• Make sure that all units are powered ON and are configured correctly.
5.2.1 L
OCAL
T
EST
—L
OCAL
A
NALOG
L
OOPBACK
(LLB) S
TANDARD
V.54
The Local Analog Loopback (LLB) test checks the performance of the local Fiber
Optic Modem, the local DTE, and the connections between them. The LLB test
runs separately at the local and at the remote site (see
Figure 5-1
).
1. Press the ANA pushbutton on the front panel to activate the LLB loopback.
2. When LLB loopback is initiated, the TEST LED lights to indicate that the
Fiber Optic Modem’s digital interface is now operationally connected to the
adjacent DTE via most of the modem circuits. You can also activate this test
via the appropriate pin on the digital interface.
