<s>
In	O
signal	O
processing	O
,	O
pre-emphasis	B-Algorithm
is	O
a	O
technique	O
to	O
protect	O
against	O
anticipated	O
noise	O
.	O
</s>
<s>
Removal	O
of	O
the	O
distortion	O
caused	O
by	O
pre-emphasis	B-Algorithm
is	O
called	O
de-emphasis	O
,	O
making	O
the	O
output	O
accurately	O
reproduce	O
the	O
original	O
input	O
.	O
</s>
<s>
Emphasis	O
is	O
commonly	O
used	O
in	O
FM	B-Application
broadcasting	O
(	O
preemphasis	O
improvement	O
)	O
and	O
vinyl	O
(	O
e.g.	O
</s>
<s>
In	O
processing	O
electronic	O
audio	O
signals	O
,	O
pre-emphasis	B-Algorithm
refers	O
to	O
a	O
system	O
process	O
designed	O
to	O
increase	O
(	O
within	O
a	O
frequency	B-Algorithm
band	I-Algorithm
)	O
the	O
magnitude	O
of	O
some	O
(	O
usually	O
higher	O
)	O
frequencies	O
with	O
respect	O
to	O
the	O
magnitude	O
of	O
other	O
(	O
usually	O
lower	O
)	O
frequencies	O
in	O
order	O
to	O
improve	O
the	O
overall	O
signal-to-noise	O
ratio	O
by	O
minimizing	O
the	O
adverse	O
effects	O
of	O
such	O
phenomena	O
as	O
attenuation	O
distortion	O
or	O
saturation	O
of	O
recording	O
media	O
in	O
subsequent	O
parts	O
of	O
the	O
system	O
.	O
</s>
<s>
Pre-emphasis	B-Algorithm
is	O
achieved	O
with	O
a	O
pre-emphasis	B-Algorithm
network	O
which	O
is	O
essentially	O
a	O
calibrated	O
filter	O
.	O
</s>
<s>
Pre-emphasis	B-Algorithm
is	O
commonly	O
used	O
in	O
telecommunications	O
,	O
digital	O
audio	O
recording	O
,	O
record	O
cutting	O
,	O
in	O
FM	B-Application
broadcasting	O
transmissions	O
,	O
and	O
in	O
displaying	O
the	O
spectrograms	O
of	O
speech	O
signals	O
.	O
</s>
<s>
Pre-emphasis	B-Algorithm
is	O
employed	O
in	O
frequency	B-Application
modulation	I-Application
or	O
phase	B-Device
modulation	I-Device
transmitters	O
to	O
equalize	O
the	O
modulating	O
signal	O
drive	O
power	O
in	O
terms	O
of	O
deviation	O
ratio	O
.	O
</s>
<s>
The	O
receiver	O
demodulation	B-Device
process	O
includes	O
a	O
reciprocal	O
network	O
,	O
called	O
a	O
de-emphasis	O
network	O
,	O
to	O
restore	O
the	O
original	O
signal	O
power	O
distribution	O
.	O
</s>
<s>
In	O
telecommunication	O
,	O
de-emphasis	O
is	O
the	O
complement	O
of	O
pre-emphasis	B-Algorithm
,	O
in	O
the	O
antinoise	O
system	O
called	O
emphasis	O
.	O
</s>
<s>
As	O
CDs	O
were	O
originally	O
intended	O
to	O
work	O
on	O
14-bit	O
audio	O
,	O
a	O
specification	O
for	O
'	O
pre-emphasis	B-Algorithm
'	O
was	O
included	O
to	O
compensate	O
for	O
quantization	O
noise	O
.	O
</s>
<s>
The	O
pre-emphasis	B-Algorithm
is	O
described	O
as	O
a	O
first-order	O
filter	O
with	O
a	O
gain	O
of	O
10dB	O
(	O
at	O
20dB/decade	O
)	O
and	O
time	O
constants	O
50μs	O
and	O
15μs	O
.	O
</s>
<s>
In	O
high	O
speed	O
digital	O
transmission	O
,	O
pre-emphasis	B-Algorithm
is	O
used	O
to	O
improve	O
signal	O
quality	O
at	O
the	O
output	O
of	O
a	O
data	O
transmission	O
.	O
</s>
<s>
In	O
transmitting	O
signals	O
at	O
high	O
data	O
rates	O
,	O
the	O
transmission	O
medium	O
may	O
introduce	O
distortions	O
,	O
so	O
pre-emphasis	B-Algorithm
is	O
used	O
to	O
distort	O
the	O
transmitted	O
signal	O
to	O
correct	O
for	O
this	O
distortion	O
.	O
</s>
<s>
In	O
serial	B-Protocol
data	I-Protocol
transmission	I-Protocol
,	O
de-emphasis	O
has	O
a	O
different	O
meaning	O
,	O
which	O
is	O
to	O
reduce	O
the	O
level	O
of	O
all	O
bits	O
except	O
the	O
first	O
one	O
after	O
a	O
transition	O
.	O
</s>
