User's Manual
ADCP-75-110 • Issue 2B • July 2001
Page 3
©
2001,
ADC
Telecommunications,
Inc.
1.1.4 Digital Fiber Optic Transport
The
DHU
is
connected
to
each
DRU
unit
over
a
pair
of
multi-mode
fiber
optic
links.
One
link
is
used
to
transport
the
forward
path
optical
signal.
The
other
link
is
used
to
transport
the
reverse
path
optical
signal.
Because
the
optical
signal
is
digital,
no
adjustments
to
the
optical
signal
level
are
required
at
the
DRU
or
the
DHU
regardless
of
the
length
of
the
optical
link.
Either
50
or
62.5
micron
core
multi-mode
fiber
optic
cable
may
be
used
for
the
optical
link.
If
50
micron
cable
is
used,
the
optical
link
may
be
up
to
750
meters
in
length.
If
62.5
micron
core
cable
is
used,
the
optical
link
may
be
up
to
500
meters
in
length.
The
fiber
optic
links
are
terminated
with
LC
connectors.
1.1.5 Capacity for Expansion and Extended Runs
The
DEU
enables
6-way
expansion
of
any
optical
port.
This
makes
it
possible
to
add
more
DRUs
without
having
to
install
additional
DHUs.
Each
DHU
is
equipped
with
six
optical
ports.
If
more
than
six
DRUs
are
required
by
the
application,
a
DEU
may
be
connected
to
one
of
the
optical
ports
at
the
DHU
which
expands
that
port
to
six
ports.
If
still
more
optical
ports
are
required,
then
a
second
DEU
may
be
connected
to
the
DHU
or
a
second
DEU
may
be
connected
to
the
first
DEU.
The
ability
to
cascade
DEU’s
in
parallel
or
in
series
provides
unlimited
flexibility.
It
is
physically
possible
to
connect
an
unlimited
number
DRUs
to
the
DHU
through
the
installation
of
DEUs.
The
maximum
number
of
DRUs
that
can
connected
to
the
DHU
is
limited
only
by
the
cumulative
noise
effect
caused
by
antenna
combining.
1.1.6 Power Requirements
The
DHU,
DEU,
LIU,
and
RIU
are
each
powered
by
120–240
Vac
(50–60
Hz)
power
which
is
supplied
through
a
standard
three-conductor
AC
power
cord.
The
DRU
is
powered
by
34–48
Vdc
which
is
supplied
by
either
the
DHU,
DEU,
or
an
ac/dc
wall-mount
style
converter.
When
the
DRU
is
powered
by
the
DHU
or
DEU,
the
power
is
fed
through
a
category
3
or
5
cable
terminated
with
male
RJ-45
connectors.
1.1.7 Fault Detection and Alarm Reporting
LED
indicators
are
provided
on
the
front
panel
of
the
various
units
to
indicate
if
the
system
is
normal
or
if
a
fault
is
detected.
In
addition,
normally
open
and
normally
closed
alarm
contacts
(for
both
major
and
minor
alarms)
are
provided
at
the
DHU
for
connection
to
a
customer
provided
external
alarm
system.
This
could
be
a
local
system
or
automatic
call-out
system.
1.2 Digital Host Unit Description
The
DHU,
shown
in
Figure
2,
serves
as
the
BTS
servicing
unit
for
the
Digivance
ICS.
The
DHU
provides
the
following
basic
functions:
• RF
inputs
and
outputs
• Optical
interface
to
the
DRUs
or
DEUs
• Digitizing
of
the
cellular
forward
path
RF
signal