Unit installation

FCD-E1 Installation and Operation Manual Chapter 6 Troubleshooting and Diagnostics
Testing FCD-E1 6-19
Transmission
Plant
User DTE
LOCAL FCD-E1
E1 Sub
DSU LTU
REMOTE FCD-E1
E1 Sub
DSULTU
User DTE
Figure 6-2. Main Link Remote Analog Loopback
Main Link Local Digital Loopback (LP LOC DIG ML)
This loopback is performed by connecting the E1 digital transmit signal of the main
link to the input of the receive path, without passing through the main link
interface. Signal paths are shown in Figure 6-3.
LOCAL FCD-E1
E1 Sub
DSU
LTU
User DTE
"1"
All Ones
Figure 6-3. Main Link Local Digital Loopback
Before connecting this loopback on an FCD-E1 with an Ethernet port, disconnect
the LAN cable from the rear panel Ethernet interface.
The test signal is provided by the equipment connected to the local ports: each one
must receive its own transmission. The NOTE regarding BER testing on the sublink
when the local analog loopback is active also applies to the local digital loopback.
This test checks the digital circuits of the local FCD-E1 (DSU section.), and the
connections to the local user equipment.
Sublink Local Analog Loopback (LP LOC ANA SL)
Local analog loopback towards the local sublink. Performed by connecting the
sublink transmit signal to the input of the sub receive path, as shown in Figure 6-4.
The test signal is provided by the equipment connected to the local sublink, that
must receive its own transmission.
This test fully checks the connections to the equipment connected to the local
sublink.
Not
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