Turnup; Operation; Testing - ADTRAN NIU3 Installation And Maintenance Practice

• To initiate a dual (bidirectional) loopback, depress
three times and hold for 5 seconds. During this
SW1
time the
NTWK LBK
rapidly indicating the dual loopback is arming.
After 5 seconds the dual loopback enables, the
and
NTWK LBK CUST LBK
and can be released.
SW1
If is released before the arming period expires the
SW1
loopback does not initiate. This feature decreases the
chance of an inadvertent loopback.
If a loopback is in effect, depressing
the loopback regardless of initiation point.
Loopback priority is in response to the most recent local
or remote input. The
LBK

3. TURNUP

When inserted into a host with power, the
turns on red while the NIU3 PM performs a
self-test. If the self-test passes, the
on green and the remaining LEDs go through an on/off
sequence indicating the NIU3 PM is online. If the test
fails, the LED remains red and the host bypass
STATUS
relays will maintain data flow around the NIU3 PM.
Shutdown procedures are not required.

4. OPERATION

During normal operation the NIU3 PM is transparent to
the network. In the event of circuit trouble, test
equipment at the central office control terminal can
monitor the loop. When a loopback is initiated, the
transmit/receive paths can be tested to the customer
interface.
Monitoring
Front panel mid-size monitoring jacks provide
nonintrusive monitoring access through a high-
impedance bridging circuit. The monitor level is
nominally 21.5 dB below the signal power. The signal
to the network is monitored via the
the signal to the customer is monitored via the
jack.
MON
Loss of Signal
In the event of a loss of signal, the NIU3 PM provides
both a "keep alive" signal and LED notification.
• If there is no signal from the network, the
LED turns on red, and the NIU3 PM will
LOS/AIS
transmit an unframed all ones signal toward the
customer.
• If there is no signal from the customer, the
LED turns on red, and the NIU3 PM will
LOS/AIS
6
and LEDs flash
CUST LBK
LEDs turn on solid,
will disable
SW1
LEDs show status.
STATUS
LED turns
STATUS
jack;
NTWK MON
CUST
NTWK
CUST
transmit the signal selected by
Provisioning
sent to the network upon customer LOS are these:
– Framed Idle
– AIS
– No Signal
Loss of Framing
If either
NTWK
off, the associated network or customer signal is
unframed.

5. TESTING

The NIU3 is compatible with standard test equipment.
Digital testing is accomplished with the T-BERD 310 or
equivalent.
LED
FEAC Loopback
The test device at the CO inserts a DS3 NIU FEAC (Far
End Alarm and Control) loop up code (C-bit parity
framing only) toward the NIU3. The NIU3 then
performs a network loopback. The loopback is
terminated by a DS3 NIU FEAC loop down code.
Loopback and Bypass Configurations
There are four basic NIU3 normal/loopback configu-
rations:
I Normal Operation
II Network Loopback
III Customer Loopback
IV Dual Loopback
Each configuration is shown in a block diagram in
Figure 6. Each block diagram represents the NIU3
circuit card in normal operation or a particular
loopback.
Each block diagram illustrates the relative position of
the detecting circuits to one another and the LED
indication associated with each, plus the location of the
mid-size monitoring jacks. See Table 1 for LED
descriptions.
Bypass Operation
The bypass relays are represented in block diagram I
only. The bypass relays are independent of the NIU3
circuit card and loopback configurations. The relays
switch to the bypass position during one of the
following conditions:
• The NIU3 circuit card fails or loses power
• The NIU3 circuit card is removed
• Flash upgrade is in progress
Option 3
menu. The three selections that can be
or and
CUST C-Bit M13
on the
LEDs are both
61212075L2-5D