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CHAPTER 6: Troubleshooting
6. Troubleshooting
This chapter explains
The line driver provides local loopback and remote digital loopback in compliance with the V.54 standard. Unless you disable them, the unit’s loopback tests can be activated manually from the unit’s front panel, and the local analog and remote digital loopbacks can be activated electronically through the DTE connection.
6.1 Loop Tests
The
6.2 The Bit-Error-Rate Tester (BERT)
You can activate the line driver’s internal Bit Error Rate Tester in any diagnostics test in which the transmitted test pattern is looped back to the BERT for comparison. An example is shown in Figure
The line driver is also capable of operating opposite any 511 BERT tester. When you use one line driver opposite another, either with one or both PATT buttons pressed (see Figure
NOTE
For the line driver’s BERT to operate correctly, the CARRIER jumper must be set to ON or the RTS signal must be high.
While PATT is pressed, the V.35 interface is functionally disconnected.
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