Dds Testing; Local Analog Loopback Testing - Black Box MT160A Manual

MicroCSU/DSU Cards and MicroRacks
The MicroCSU/DSU offers three tests to evaluate the condition of the CSU/DSUs
and the communication link: local analog loopback testing, remote digital
loopback testing, and telco testing. This section describes how to utilize each of
these test modes.

6.1 Local Analog Loopback Testing

The Local Analog Loopback (LAL) test checks the operation of the local
MicroCSU/DSU. Any data sent to the local MicroCSU/DSU 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 terminal screen. To perform an
Analog Loopback test, follow these steps:
1) Activate Analog Loopback. This may be done in one of two ways: by moving
the front-panel toggle switch to Analog or by raising signal LL on the terminal
interface. Once LAL is activated, the MicroCSU/DSU transmit output is
connected to its own receiver. The "test" LED should be lit.
2) Verify that the data terminal equipment is operating properly and can be used
for a test. If a fault is indicated, call your supplier.
3) Perform a BER (bit error rate) test on each unit. If the BER test equipment
indicates no faults but the data terminal indicates a fault, follow the
manufacturer's checkout procedures for the data terminal. Also, check the
interface cable between the terminal and the MicroCSU/DSU.
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6. DDS Testing

CSU/DSU