Setting up a loopback BERT test with the 635 T1 tester

To perform a loopback BERT, proceed with the following steps:

Set the Rx Input Termination to term.
Select the correct Framing and line coding.
Plug into the NTWK OUT jack with the test set Rx cable and plug the Tx cable into the NTWK IN jack.
Select Internal as the Tx clock source.
Select the Bert pattern you want to test with.
Loop up the far end CSU loop code by selecting CSU loop code and pressing the loop Up key.
Verify that no bit errors occur for each BERT pattern used in testing. Be sure to clear errors after changing BERT patterns.
Loop the CSU Down when testing is complete.

This test will identify problems, but will not identify on which side of the span the problem is located.