User Manual
ADCP-75-114 • Issue 2C • January 2002
Page 3
©
2002,
ADC
Telecommunications,
Inc.
1.3 Fault Detection and Alarm Reporting
The
RIU
is
designed
to
detect
a
power
amplifier
over
or
under
current
condition
and
a
high
temperature
condition.
A
single
front
panel
Light
Emitting
Diode
(LED)
indicator
turns
from
green
to
red
or
yellow
if
a
fault
is
detected.
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
(power
amplifier
over/undercurrent
condition
or
power
failure)
and
minor
alarm
(high
temperature)
contacts
are
provided.
1.4 RF Signal Connections
The
RF
signal
connections
between
the
RIU
and
DHU
are
supported
through
a
pair
of
type
N
female
connectors
mounted
on
the
RIU
front
panel.
One
connector
is
used
for
connecting
the
forward
path
coaxial
cable
and
the
other
connector
is
used
for
connecting
the
reverse
path
coaxial
cable.
The
RF
signal
connection
between
the
RIU
and
the
donor
antenna
is
supported
through
a
single
type
N
female
connector.
The
single
connector
is
used
for
connecting
the
coaxial
jumper
cable
that
links
the
RIU
to
the
donor
antenna.
The
DHU
cannot
be
connected
directly
to
a
donor
antenna
and
requires
an
interface
device
such
as
the
RIU.
1.5 RF Signal Level Adjustments
The
RIU
is
equipped
with
two
digital
attenuators
for
adjusting
the
signal
levels
of
the
forward
and
reverse
path
RF
signals.
The
attenuators
provide
an
attenuation
adjustment
range
of
0
to
31
dB
and
can
be
set
in
1
dB
increments.
In
the
forward
path,
this
range
provides
a
maximum
gain
of
+40
dB
(attenuator
set
to
0)
or
a
minimum
gain
of
+9
dB
(attenuator
set
to
31
dB).
In
the
reverse
path
for
800
MHz
units,
this
range
provides
a
maximum
gain
of
+59
dB
(attenuator
set
to
0)
or
a
minimum
gain
of
+28
dB
(attenuator
set
to
31
dB).
In
the
reverse
path
for
1900
MHz
units,
this
range
provides
a
maximum
gain
of
+64
dB
(attenuator
set
to
0)
or
a
minimum
gain
of
+33
dB
(with
attenuator
set
to
31
dB).
Each
attenuator
is
adjustable
by
means
of
two
rotary
switches
which
are
mounted
behind
the
RIU
front
panel.
Access
to
each
rotary
switch
is
through
a
small
hole.
A
small
screwdriver
is
required
to
adjust
the
switch
setting.
Turning
each
switch
adds
or
removes
attenuation
and
therefore
adjusts
the
signal
level
of
the
specified
signal
path.
1.6 Powering
The
RIU
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
RIU
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
RIU
internal
power
supply.
1.7 Cooling
Continuous
air
flow
for
cooling
is
provided
by
a
fan
mounted
on
the
right
side
of
the
housing.
A
minimum
of
3
inches
(76
mm)
of
clearance
space
must
be
provided
on
both
the
left
and
right
sides
of
the
RIU
for
air
intake
and
exhaust.
An
alarm
is
provided
that
indicates
if
a
high
temperature
condition
(>58º
C/136º
F)
occurs.
The
fan
may
be
field-replaced
if
it
fails.