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2 Section 61212075L1-5, Issue 3 61212075L1-5C
Description
The NIU3 resides at the remote location next to
customer premises equipment and is housed in either a
standalone or shelf enclosure.
The NIU3 is designed to loopback test data
originating at the CO and responds to commands
inserted into the data stream by a test head or portable
test set. The loopback can isolate problems located on
the customer side of the demarcation point, thus
eliminating the need for an immediate trouble-call
dispatch. The NIU3 is transparent to data transmission
during normal operation. If the NIU3 fails or is
removed from its host circuit board, bypass relays on
the host ensure circuit continuity to maintain data flow
between the network and the customer. A front panel
LED on the NIU3 provides notification of failure. See
Figure 2 for a circuit diagram of the NIU3 in a DS3
network delivered via SONET.
2. INSTALLATION
After unpacking the unit inspect it for damage. If
damage is noted, file a claim with the carrier, then
contact ADTRAN. See Warranty and Customer
Service.
This product is intended for use in a restricted access
area in a Type “B” or “E” enclosure only.
Location
In either housing configuration, the NIU3 installs at
any location convenient to the customer. The NIU3
can pass both network and customer signals up to 900
feet. However, if either distance exceeds 450 feet, the
respective front panel monitoring signal begins to
degrade. Also, during NIU3 bypass operations, if total
transmission distance exceeds 900 feet, signal quality
may degrade. See Figure 2 for maximum
recommended transmission distances.
The NIU3 inserts into the host circuit board of either
the standalone housing or the shelf. The unit is
secured with the two front panel thumbscrews.
Jack Connections
Both housings have four rear panel BNC connectors
for each NIU3: two (IN/OUT) for customer receive/
transmit, and two (IN/OUT) for network receive/
transmit. Two additional jacks on the NIU3 front
panel provide a nonintrusive network and customer
monitoring point. The standalone housing or shelf
security panel must be opened to access the
monitoring jacks.
Standalone Power
The NIU3 operates on local -48 VDC. The standalone
housing has a power wire portal on the rear panel for
termination on the host circuit board at TB1, which
has terminals for 48V(-), 48V(+)/GND, and Frame
Ground (see Figure 3).
Standalone Power Option
An optional standalone unit power source is from a
standard 120 VAC wall outlet via a separately
purchased transformer with 48 VDC @ 200 mA
output.
C A U T I O N
C A U T I O N
!
SUBJECT TO ELECTROSTATIC DAMAGE
OR DECREASE IN RELIABILITY.
HANDLING PRECAUTIONS REQUIRED.
Figure 2. DS3 NIU Loopback Diagram