— Set the front panel switch to “Remote”.
2.Perform a bit error rate test (BERT) using the internal V.52 genera- tor (as described in section “Using the V.52 (BER) Test Pattern Generator”), or using a separate BER Tester. If the BER test indi- cates a fault, and the Local Line Loopback test was successful for both NetLink devices, you may have a problem with the twisted pair line connection.
CSU Loop
Although CSU Loop is predominantly a T1 function, the
When CSU Loop is selected, the NetLink 2701 will implement the “loop up” command when it recognizes the pattern “10000” in the data stream for a minimum of 5 seconds. The “loop down” command is implemented by the pattern “100” in the data stream for a minimum of 5 seconds.
The NetLink 2701 will respond to Universal Loopback
Using the V.52 (BER) Test Pattern Generator
To use the V.52 BER tests in conjunction with the Remote Digital Loop- back tests (or with Local Line Loopback tests), follow these instructions:
1.Locate the “511/511E” toggle switch on the front panel of the 2701 and move it UP. This activates the V.52 BER test mode and transmits a “511” test pattern into the loop. If any errors are present, the local modem’s red “ER” LED will illuminate.
2.If the above test indicates no errors are present, move the V.52 tog- gle switch DOWN, activating the “511/E” test with errors present. If the test is working properly, the local modem's red “ER” LED will blink once every second. A successful “511/E” test will confirm that the link is in place, and that the Model 2701’s
Note The above V.52 BER tests can be used independently of the Remote Digital Loopback tests. This requires two operators: one to initiate and monitor the tests at the local Model 2701, and one to do the same at the remote Model 2701. In this case, the test pattern sent by each Model 2701 will not be looped back, but will be transmitted down the line to the other Model 2701. While one operator initiates test, the other monitors for errors.
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