User guide

August 2001 93
Understanding E1 Trunks
To check for bipolar violations, call RHT_GET_STATUS. See
Troubleshooting on page 134 for more information about how to
handle bipolar violations.
Figure 17. A Bipolar Violation in AMI Coding
In AMI signaling, a long series of zeros is represented by a
constant 0V signal. The two ends can lose timing if there is no
signal on the line to synchronize them. To maintain ones
density on the line, some carriers use a coding method called
HDB3 that replace a series of four zeros with a ones-rich
pattern. In HDB3 signaling, an inserted one forms a bipolar
violation which flags that pattern to be replaced by a series of
zeros at the remote end.
E1 boards support line coding with or without HDB3. You set
which line coding method your system uses when you configure
the carrier as described in Configuring the Carrier on page 105.
00110
0
11
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r Violation