User Manual
ADCP-75-136 • Issue 1 • November 2002
Page 17
©
2002,
ADC
Telecommunications,
Inc.
3.1.2 Remote BTS (Cell Site Base Station) Interface
A
remote
interface
between
the
DHU
and
the
BTS
(cell
site
base
station)
via
a
donor
antenna
requires
specific
RF
input
and
output
signal
levels
at
the
DHU
and
antenna.
The
correct
levels
at
the
DHU
and
antenna
can
be
provided
using
a
remote
interface
device
(ancillary
product).
A
block
diagram
of
a
typical
remote
DHU
to
BTS
interface
is
shown
in
Figure
9.
DIRECTIONAL
ANTENNA TO/FROM
CELL SITE BTS
18111-A
REMOTE
INTERFACE
DEVICE
(ANCILLARY
PRODUCT)
FORWARD
(DOWNLINK)
REVERSE
(UPLINK)
+13 dBm
(COMPOSITE
MAX)
-40 dBm
(COMPOSITE
MAX)-20 dBm
(COMPOSITE
MAX)
-30 dBm
(COMPOSITE
MAX)
DIGITAL
HOST
UNIT
OPTICAL LINK
OPTICAL LINK
DIGITAL
REMOTE
UNIT
DIRECTIONAL ANTENNA
TO/FROM HANDSETS
Figure 9. Remote BTS Interface Block Diagram
In
the
forward
path
(downlink),
the
recommended
composite
maximum
RF
input
signal
level
at
the
DHU
is
–20
dBm.
When
the
level
of
the
RF
input
signal
at
the
DHU
is
–20
dBm,
the
level
of
the
RF
output
signal
at
the
DRU
will
be
+13
dBm.
In
the
reverse
path,
the
RF
output
signal
level
required
at
the
donor
antenna
will
vary
depending
on
the
distance
from
the
BTS.
When
the
level
of
the
reverse
path
(uplink)
signal
at
the
DRU
is
at
the
recommended
composite
maximum
level
of
–40
dBm,
the
level
of
the
RF
output
signal
from
the
DHU
with
be
–30
dBm.
Therefore,
it
will
generally
be
necessary
to
add
some
gain
to
the
reverse
path
signal
in
order
to
provide
the
output
RF
signal
level
required
at
the
donor
antenna.
3.2 Location and Mounting Requirements
3.2.1 DHU and DEU Location and Mounting Requirements
The
DHU
and
the
DEU
may
be
either
rack
mounted
or
wall
mounted.
Fasteners
(both
metric
and
US
standard)
are
included
with
each
unit
for
rack
mount
applications.
A
pair
of
reversible
mounting
brackets
is
provided
that
allows
the
unit
to
be
mounted
in
either
a
19-inch
or
23-inch
EIA
or
WECO
equipment
rack.
When
rack-mounted,
the
front
panel
of
the
unit
is
flush
with
the
front
of
the
rack.
The
cable
management
tray
extends
3.9
inches
(99
mm)
beyond
the
front
panel.
Both
the
DHU
and
DEU
occupy
3.5
inches
(89
mm)
of
rack
space.
Make
sure
the
mechanical
loading
of
the
rack
will
be
even
to
avoid
a
hazardous
condition
such
as
a
severely
unbalanced
rack.
The
rack
should
safely
support
the
combined
weight
of
all
the
equipment
it
holds
and
be
properly
anchored.