ADTRAN DE-4E - Manual (Page 18)

A-2 Section 61245207L2-5, Issue 3 61245207L2-5C
There is one loopback available to the FT1 Repeaters.
The FT1 Repeater Network loopback is a digital
loopback toward the CO as shown in Figure A-4.
The loopbacks are initiated by the DDS latching
loopback codes for NEI Position 1 (N1000001) for
FT1 #1 or NEI Position 2 (N100001) for FT1
Repeater # 2. The NEI latching loopback is detected
in the primary DS0 of the FT1 circuit, the channel
where the FT1 DP is physically installed, to control
the looping of the FT1 circuit. When the FT1 circuit
is looped, all DS0s in use will be looped. The DS0s in
use will also be transmitted on to the customer.
There are two loopbacks available to the FNID. The
FNID network loopback loops the FT1 signal back
toward the network. The FNID CPE loopback loops
the FT1 signal back toward the customer.
The FNID network loopback is a digital loopback
toward the CO as illustrated in Figure A-5. This
loopback is initiated by the DDS latching loopback
code for NEI Position 1 (N1000001) for a
non-repeatered loop, or NEI Position 2 (N1000001)
for a single repeater loop or by NEI Position 3
(N1000001) for a two repeater loop; by the craft
interface when available, or by the REM LBK button
at the FT1 DP. The NEI Position 1 latching loopback
is detected in the primary DS0 of the FT1 circuit (the
channel in which the FT1 DP is physically installed),
to control the looping of the FT1 circuit. When the
FT1 circuit is looped, all DS0s in use will be looped.
The DS0s in use will be filled with all 1s and
transmitted toward the customer.
The FNID CPE loopback is a digital loopback toward
customer premises as shown in Figure A-6. This
loopback is initiated by the craft interface, when
available. When the FT1 circuit is looped, all DS0s in
use will be looped. The data in the DS0s in use will
be transmitted toward the network.
Figure A-4. FT1 Repeater # 1 or 2 Network Loopback
DSX-1
Interface
Central Office
FT1 DP
D4
Channel Bank
FNID
HDSL
Local Loop
DS1
Interface
Customer Premises
FT1
Repeater
# 1 or 2
Figure A-5. FNID Network Loopback
DSX-1
Interface
Central Office
FT1 DP
D4
Channel Bank
FNID
HDSL
Local Loop
DS1
Interface
Customer Premises
Figure A-6. FNID CPE Loopback
DSX-1
Interface
Central Office
FT1 DP
D4
Channel Bank
FT1-NID
HDSL
Local Loop
DS1
Interface
Customer Premises