Checking The Transmission Between Cascaded Trxs; Figure 6-6 Physical Loopback Of E1/T1 At The Ddf - Huawei BTS3900 GSM Commissioning Manual

6 Optional Commissioning Tasks
1.
2.
3.
Step 6 Check the E1/T1 connections at the DDF. Ensure that the TX and RX ends of the E1 cables are
connected properly.
----End

6.5 Checking the Transmission Between Cascaded TRXs

This describes how to check the transmission between cascaded TRXs. The following
description is based on three levels of cascaded TRXs.
Prerequisite
The physical connection between cascaded TRXs on the BTS side is complete.
6-12
For a pair of E1s/T1s connecting the BTS and BSC through the DDF, the A port is connected
to the C port, and the B port is connected to the D port. In the loopback test, disconnect the
A port from the C port, and the B port from the D port, and then connect the A port to the
B port, as shown in Figure
connected and the physical loopback is formed on the BTS side.

Figure 6-6 Physical loopback of E1/T1 at the DDF

Check the status of the LIU LEDs on the GTMU panel again.
If...
The LEDs are OFF
The LEDs are ON or ON for 0.125s and
OFF for 0.125s
Set the E1s/T1s at the DDF on the BTS side from physical loopback to normal connection.
Ensure that the connections are sound.
NOTE
Do as follows to distinguish the E1 RX end from the E1 TX end:
Connect a pin of an LED to the wire of the E1/T1 cable, and the other pin to the shielding layer of the E1/
T1 cable. If the LED is ON, this end is the TX end. If the LED is OFF, this end is the RX end.
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6-6. In this way, the TX end and RX end of the E1/T1 line is
Then...
The E1/T1 connections are normal on the
BTS side. The problem may be that the
connection between the BTS and the BSC or
the connections on the BSC side are faulty.
End the check, and contact the BSC
technical support engineer to clear the fault.
The cable connections on the BTS side are
faulty. Clear the fault on the BTS side.
BTS3900(A) GSM
Commissioning Guide
Issue 02 (2009-04-20)