Dte Interface Loopbacks; Pattern Generation; Figure 1-6. Dte Interface Loopback - ADTRAN TSU LT User Manual

Chapter 1. Introduction

DTE Interface Loopbacks

The Nx56K/64K serial interface offers a DTE loopback. See Figure 1-6.
DTE Loopback
Loops all data from the DTE back towards the DTE. This loopback may be initiated by the DTE
asserting the local loopback (LL) input on the connector or by using the front panel or T-Watch
commands. The DTE (or the external test equipment) must provide a test pattern to check the DTE
interface.

Pattern Generation

The TSU LT offers four available test patterns: 511, 1:8, All Ones, and All Zeros.
511
The 511 pattern is generated and checked by the Nx56K/64K serial interface. It only appears in the
DS0s assigned to the Nx56K/64K port. When used in conjunction with the payload loopback at the far
end, an end-to-end integrity check can be made on the DTE ports.
1:8
The 1:8 is a stress pattern which places the maximum number of 0s in the transmitted data. This is
always done over all DS0s. This pattern is used in conjunction with external test equipment to
determine if the T1 line is performing acceptably under a stress condition. Each channel of the T1 has
only one bit set.
All Zeros
Generates an all zeros pattern in every channel.
All Ones
Generates an all ones pattern in every channel.
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Figure 1-6. DTE Interface Loopback

© 2002 ADTRAN, Inc.
TSU LT User Manual
61202060L4-1