Chapter 5. Loop Back and BERT Testing
93
November 2001
E1 line local analog loop back
The E1 line local analog loop back is performed by connecting the
main link transmit signal to the input of the receive path in the
Channel Service Unit (CSU), as shown in Figure 5-1. This returns
the transmit signal of the Data port to the receive path of the Data
port. The Data Port must receive its own transmission. This loop
back fully tests the local ETU-01A operation and the connections
to the local DTE. During this loop back, the ETU-01A E1 line
sends an unframed “all ones” signal to the remote equipment.
Before initiating this loop back, disconnect the LAN cable from the
rear panel Ethernet Bridge interface.
Figure 5-1. E1 link local analog loop back
“1”
User
DTE
Data
Port
E1
E1 LINE
LOCAL ETU-01A
DSU
CSU
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