User Manual
ADCP-75-136 • Issue 1 • November 2002
Page 5
©
2002,
ADC
Telecommunications,
Inc.
2.1.2 Mounting
The
DHU
may
be
used
in
both
rack-mount
and
wall-mount
applications.
For
rack
mount
applications,
a
pair
of
reversible
mounting
brackets
is
provided
that
allow
the
DHU
to
be
mounted
in
either
a
19-inch
or
23-inch
EIA
or
WECO
equipment
rack.
When
rack-mounted,
the
front
panel
of
the
DHU
is
flush
with
the
front
of
the
rack
and
the
cable
management
tray
extends
3.9
inches
(99
mm)
beyond
the
front
panel.
For
wall-mount
applications,
a
pair
of
holes
is
provided
in
the
cable
management
tray
which
allow
the
DHU
to
be
mounted
on
any
flat
vertical
surface.
The
DHU
should
be
oriented
with
the
front
panel
facing
upward
when
wall-mounted.
Fasteners
are
provided
for
rack-mount
applications.
2.1.3 Fault Detection and Alarm Reporting
The
DHU
detects
internal
circuitry
faults
and
optical
port
faults.
Various
front
panel
Light
Emitting
Diode
(LED)
indicators
turn
from
green
to
red
or
yellow
if
a
fault
is
detected
or
an
optical
input
is
lost.
A
set
of
alarm
contacts
(normally
open
and
normally
closed)
are
also
provided
for
reporting
an
alarm
to
an
external
alarm
system
when
a
fault
is
detected.
Both
major
alarm
(all
fault
conditions
except
high
temperature)
and
minor
alarm
(high
temperature
fault
condition)
contacts
are
provided.
2.1.4 RF Signal Connections
The
RF
signal
connections
with
the
BTS
are
supported
through
two
type
N
female
connectors.
One
connector
is
used
for
coaxial
cable
connection
of
the
forward
path
RF
signal.
The
other
connector
is
used
for
coaxial
cable
connection
of
the
reverse
path
RF
signal.
In
most
installations,
the
DHU
will
not
connect
directly
to
the
BTS
but
will
be
connected
to
an
interface
device
(ancillary
product).
The
DHU
requires
a
composite
forward
path
RF
signal
level
of
–20
dBm
or
lower.
An
overdrive
limiter
protects
the
system
against
excessive
inputs
but
does
not
function
during
normal
operation.
The
DHU
does
not
have
Automatic
Gain
Control
(AGC).
2.1.5 Optical and Electrical Connections
The
optical
and
electrical
connections
with
the
DRU’s
and
DEU’s
are
supported
by
six
optical
and
six
electrical
ports.
Each
optical
and
electrical
port
includes
a
status
LED,
a
small
form
factor
LC-type
optical
transceiver,
an
RJ-45
DC
power
jack,
and
a
port
enable/disable
switch.
Each
transceiver
is
color-coded
to
identify
whether
it
supports
single-mode
(blue)
or
multi-mode
(black/beige)
fiber.
An
optical
port
may
be
connected
to
a
DRU,
a
DEU,
or
not
used.
An
electrical
port
may
be
connected
to
a
DRU
or
not
used.
Unused
ports
are
disabled
via
the
corresponding
port
enable/disable
switch.
When
disabled,
the
port
LED
is
off,
the
alarm
reporting
function
is
disabled,
the
laser
is
off,
and
the
DC
power
is
off.
Enabling
the
enable/disable
switch
activates
all
functions.
The
modular
optical
transceivers
are
available
separately
as
accessory
items
and
are
field
replaceable.
2.1.6 Powering
The
DHU
is
powered
by
120–240
Vac
(50–60
Hz)
power
which
is
supplied
through
a
standard
three-conductor
AC
power
cord.
The
power
cord
is
provided
with
the
DHU
and
is
98
inches
(2.5
meters
)
long.
A
resetable
circuit
breaker/On-Off
switch
is
provided
at
the
unit
front
panel.
The
switch
applies
power
to
the
DHU
internal
power
supply.