earphone
,
active
sound
b
ox
or
amplifier
-
drive
audio
output
device.
If
the
sound
b
ox
and
the
pic
k-
up
cannot
b
e
separated
spatiall
y,
it
is
eas
y
to
arouse
s
q
uea
k
ing.
A
t
this
time
y
ou
can
adopt
the
following
measures
:
ǃ
Use
b
etter
sound
pic
k-
up
with
b
etter
directing
propert
y
.
ǃ
Reduce
the
volume
of
the
sound
b
ox
to
the
value
under
which
s
q
uea
k
ing
will
not
happen.
ǃ
Using
more
sound
-
a
b
sor
b
ing
materials
in
decoration
can
b
enefit
to
reduce
voice
echo
and
improve
acoustics
environment.
4
ǃ
A
djust
the
la
y
out
to
reduce
happening
of
the
s
q
uea
k
ing.
2.4 Connection of alar
m
input and output de
v
ices
B
efore
connection
,
please
pa
y
attention
to
the
following
points
:
1.
A
larm
input
a.
First
confirm
if
the
alarm
input
is
grounding
alarm
input
or
voltage
alarm
input.
b
.
A
larm
input
:
Grounding
signal
is
needed
for
alarm
input.
2.
A
larm
output
The
alarm
output
port
should
not
b
e
connected
to
high
power
load
directl
y
to
avoid
heav
y
current
which
will
destro
y
the
rela
y, b
ut
y
ou
can
use
the
cocontactor
to
reali
z
e
the
connection
b
etween
the
alarm
output
port
and
the
load.
3
.
How
to
connect
PTZ
decoder
a.
Ensure
the
decoder
has
the
same
grounding
with
DVR
,
otherwise
possi
b
le
common
mode
voltage
ma
y
fail
to
control
the
PTZ.
Shielded
twisted
wire
is
recommended
and
the
shielded
la
y
er
is
used
to
connect
to
the
grounding.
b
.
A
void
the
entr
y
of
high
voltage.
Ensure
proper
wiring
and
some
thunder
protection
measures
c.
For
too
long
signal
wires
,
12
0
¡
should
b
e
parallel
connected
b
etween
A, B
lines
on
the
far
end
to
reduce
reflection
and
guarantee
the
signal
q
ualit
y
.
d.
“
48
5 A, B”
of
DVR
cannot
parallel
connect
with
“
48
5
port
”
of
other
device.
e.
The
voltage
b
etween
of
A,B
lines
of
the
decoder
should
b
e
less
than
5
v.
4*.
“+
12v
”
output
(
not
all
models
have
this
output
port
)
.
Page 16 of 52
Blue Box User Guide
Содержание Blue Box
Страница 1: ...NEMA System Marine Digital Video Recorder User Guide ...
Страница 55: ......
