Specifications

Installation and Operation Manual Chapter 6 Troubleshooting and Diagnostics
FCD-E1LC Ver. 1.0 Testing the Unit 6-19
This test checks the connections to the remote user’s equipment, all the circuits
of the remote FCD-E1LC, the main link interface functions of the remote and local
FCD-E1LC, and the transmission plant connecting the two FCD-E1LC.
Transmission
Plant
Local FCD-E1LC
Processor
Main
Link
Remote FCD-E1LC
Main
Link
User's
Equipment
Data
Channel
User's
Equipment
Sub
Link
User's
Equipment
Data
Channel
User's
Equipment
Sub
Link
Processor
Figure 6-4. Main Link Remote Digital Loopback
Inband-Activated Loopback (LP INBAND ML)
FCD-E1LC supports the inband-activated loopback function, which includes:
• Transmission of special loopback activation/deactivation codes to the remote
equipment, in user-specified timeslots of the main link interface
• Detection of inband-loopback activation/deactivation codes. The detection of
the activation code in certain main link timeslots results in the activation of
the loopback in the corresponding timeslots, and the deactivation code
cancels the loopback.
To enable the activation of a loopback in response to the reception of the inband
loopback activation code from a remote unit, use the DEF BERT ML command to
set the RX_INBAND parameter to ENABLE, and then configure the same test
timeslots and activation/deactivation patterns on both units.
Figure 6-5 shows the signal paths related to the inband-activated loopback, when
the loopback is activated on the local FCD-E1LC in response to a command
received from the remote equipment (another FCD-E1LC or other equipment
supporting the inband-activated loopback).
User's
Equipment
Local FCD-E1LC
Data
Channel
Main Link
Remote Unit (e. g. FCD-E1LC)
Sub Link
P/O Main Link
Interface
Data
Channel
User's
Equipment
Sub
Link
User's
Equipment
User's
Equipment
Transmission
Plant
Sequence
Evaluator
Sequence
Generator
Processor Processor
Figure 6-5. Inband-Activated Loopback
The loopback activated in this way is similar to the main link remote digital
loopback, except that it is performed on the local FCD-E1LC, in response to a
command entered at the remote FCD-E1LC, and only in selected timeslots .
The FCD-E1LC allows the user to specify the desired timeslots in which the
activation/deactivation sequences are sent, or instruct the FCD-E1LC to activate
the loopback in the timeslots assigned to the desired user port (data channel 1
Note