<s>
Video	B-Device
modulation	I-Device
is	O
a	O
strategy	O
of	O
transmitting	O
video	O
signal	O
in	O
the	O
field	O
of	O
radio	O
modulation	B-Application
and	O
television	O
technology	O
.	O
</s>
<s>
In	O
general	O
,	O
video	B-Device
modulation	I-Device
means	O
that	O
a	O
higher	O
frequency	O
carrier	O
wave	O
is	O
modified	O
according	O
to	O
the	O
original	O
video	O
signal	O
.	O
</s>
<s>
There	O
are	O
many	O
application	O
of	O
video	B-Device
modulation	I-Device
:	O
</s>
<s>
These	O
applications	O
all	O
utilized	O
the	O
efficiency	O
of	O
video	B-Device
modulation	I-Device
in	O
order	O
to	O
minimize	O
costs	O
.	O
</s>
<s>
There	O
are	O
some	O
important	O
concepts	O
needed	O
to	O
be	O
understood	O
in	O
order	O
to	O
fully	O
comprehend	O
the	O
video	B-Device
modulation	I-Device
.	O
</s>
<s>
Video	O
signals	O
are	O
usually	O
encoded	O
into	O
binary	O
digit	O
(	O
0	O
,	O
1	O
)	O
or	O
seven	O
digit	O
pulse-code	B-Algorithm
modulation	I-Algorithm
(	O
PCM	B-Algorithm
)	O
,	O
which	O
is	O
a	O
method	O
used	O
to	O
digitally	O
represent	O
original	O
video	O
signal	O
.	O
</s>
<s>
The	O
video	O
signal	O
converted	O
to	O
binary	O
digit	O
PCM	B-Algorithm
at	O
the	O
point	O
of	O
origin	O
can	O
be	O
then	O
transmitted	O
over	O
existing	O
telephone	O
cable	O
or	O
wire	O
directly	O
to	O
the	O
destination	O
.	O
</s>
<s>
The	O
most	O
common	O
cable	O
used	O
to	O
build	O
the	O
circuit	O
is	O
the	O
51-pair	B-Protocol
cable	I-Protocol
.	O
</s>
<s>
It	O
is	O
an	O
electronic	O
oscillator	O
that	O
uses	O
the	O
mechanical	O
resonance	B-Application
of	O
a	O
vibrating	O
crystal	O
or	O
piezoelectric	O
material	O
to	O
create	O
an	O
electrical	O
signal	O
with	O
a	O
very	O
precise	O
frequency	O
.	O
</s>
<s>
The	O
crystal	O
's	O
piezoelectric	O
property	O
converts	O
the	O
mechanical	O
vibrations	O
into	O
an	O
oscillating	B-Algorithm
voltage	O
and	O
then	O
the	O
voltage	O
is	O
picked	O
up	O
by	O
the	O
attached	O
electrodes	O
.	O
</s>
<s>
The	O
types	O
of	O
video	B-Device
modulation	I-Device
can	O
be	O
classified	O
by	O
the	O
way	O
that	O
a	O
carrier	O
wave	O
is	O
combined	O
with	O
video	O
signal	O
.	O
</s>
<s>
Hence	O
,	O
how	O
the	O
shape	O
of	O
carrier	O
wave	O
is	O
changed	O
is	O
the	O
key	O
to	O
classify	O
the	O
types	O
of	O
video	B-Device
modulation	I-Device
.	O
</s>
<s>
Amplitude	B-Application
modulation	B-Application
works	O
by	O
varying	O
the	O
amplitude	B-Application
of	O
the	O
carrier	O
wave	O
according	O
to	O
the	O
bent	O
waveform	O
of	O
original	O
video	O
signal	O
.	O
</s>
<s>
In	O
other	O
words	O
,	O
when	O
the	O
carrier	O
wave	O
is	O
combined	O
with	O
the	O
video	O
signal	O
,	O
frequency	O
of	O
the	O
combined	O
signal	O
is	O
the	O
same	O
as	O
the	O
frequency	O
of	O
the	O
carrier	O
wave	O
while	O
the	O
amplitude	B-Application
is	O
varied	O
.	O
</s>
<s>
In	O
the	O
combining	O
process	O
,	O
if	O
the	O
video	O
signal	O
is	O
at	O
its	O
peak	O
(	O
highest	O
amplitude	B-Application
value	O
)	O
,	O
the	O
amplitude	B-Application
of	O
the	O
varied	O
carrier	O
wave	O
will	O
be	O
the	O
highest	O
and	O
as	O
for	O
trough	O
(	O
lowest	O
amplitude	B-Application
value	O
)	O
,	O
the	O
amplitude	B-Application
of	O
varied	O
carrier	O
wave	O
will	O
be	O
the	O
lowest	O
.	O
</s>
<s>
In	O
fact	O
,	O
the	O
change	O
in	O
amplitude	B-Application
of	O
carrier	O
wave	O
is	O
proportional	O
to	O
the	O
amplitude	B-Application
of	O
the	O
video	O
signal	O
.	O
</s>
<s>
In	O
frequency	O
modulation	B-Application
,	O
the	O
carrier	O
wave	O
is	O
combined	O
with	O
video	O
signal	O
by	O
varying	O
the	O
instantaneous	O
frequency	O
of	O
the	O
wave	O
(	O
the	O
frequency	O
of	O
wave	O
at	O
a	O
particular	O
point	O
)	O
.	O
</s>
<s>
(	O
Compare	O
with	O
amplitude	B-Application
modulation	B-Application
,	O
in	O
which	O
the	O
amplitude	B-Application
of	O
the	O
carrier	O
wave	O
varies	O
,	O
while	O
the	O
frequency	O
remains	O
constant	O
.	O
)	O
</s>
<s>
Various	O
types	O
of	O
video	B-Device
modulation	I-Device
can	O
be	O
applied	O
in	O
various	O
areas	O
due	O
to	O
their	O
unique	O
advantages	O
and	O
disadvantages	O
.	O
</s>
<s>
AM	O
is	O
applied	O
in	O
these	O
areas	O
because	O
video	O
amplitude	B-Application
modulated	B-Application
signal	O
can	O
be	O
easily	O
coded	O
and	O
decoded	O
since	O
the	O
change	O
in	O
amplitude	B-Application
of	O
the	O
carrier	O
wave	O
and	O
the	O
amplitude	B-Application
of	O
original	O
video	O
signal	O
is	O
proportional	O
.	O
</s>
<s>
However	O
,	O
amplitude	B-Application
modulation	B-Application
is	O
sensitive	O
to	O
noise	O
and	O
electromagnetic	O
interference	O
.	O
</s>
<s>
Hence	O
,	O
the	O
AM	O
techniques	O
are	O
mainly	O
utilized	O
in	O
less	O
technical	O
fields	O
that	O
tolerate	O
noise	O
and	O
electromagnetic	O
interference	O
,	O
such	O
as	O
broadcasting	B-Operating_System
.	O
</s>
