<s>
Qualcomm	B-Algorithm
code-excited	I-Algorithm
linear	I-Algorithm
prediction	I-Algorithm
(	O
QCELP	B-Algorithm
)	O
,	O
also	O
known	O
as	O
Qualcomm	B-Algorithm
PureVoice	I-Algorithm
,	O
is	O
a	O
speech	B-Application
codec	I-Application
developed	O
in	O
1994	O
by	O
Qualcomm	O
to	O
increase	O
the	O
speech	O
quality	O
of	O
the	O
IS-96A	O
codec	O
earlier	O
used	O
in	O
CDMA	B-Protocol
networks	O
.	O
</s>
<s>
It	O
was	O
later	O
replaced	O
with	O
EVRC	B-Algorithm
since	O
it	O
provides	O
better	O
speech	O
quality	O
with	O
fewer	O
bits	O
.	O
</s>
<s>
The	O
two	O
versions	O
,	O
QCELP8	O
and	O
QCELP13	B-Algorithm
,	O
operate	O
at	O
8	O
and	O
13	O
kilobits	O
per	O
second	O
(	O
Kbit/s	O
)	O
respectively	O
.	O
</s>
<s>
In	O
CDMA	B-Protocol
systems	O
,	O
a	O
QCELP	B-Algorithm
vocoder	B-Application
converts	O
a	O
sound	O
signal	O
into	O
a	O
signal	O
transmissible	O
within	O
a	O
circuit	O
.	O
</s>
<s>
In	O
wired	O
systems	O
,	O
voice	O
signals	O
are	O
generally	O
sampled	O
at	O
8kHz	O
(	O
that	O
is	O
,	O
8,000	O
sample	O
values	O
per	O
second	O
)	O
and	O
then	O
encoded	O
by	O
8-bit	O
quantization	B-Algorithm
for	O
each	O
sample	O
value	O
.	O
</s>
<s>
A	O
QCELP	B-Algorithm
vocoder	B-Application
with	O
variable	O
rates	O
can	O
reduce	O
the	O
rate	O
enough	O
to	O
fit	O
a	O
wireless	O
system	O
by	O
coding	B-Protocol
the	O
information	O
more	O
efficiently	O
.	O
</s>
<s>
In	O
particular	O
,	O
it	O
can	O
change	O
its	O
own	O
coding	B-Protocol
rates	O
based	O
on	O
the	O
speaker	O
's	O
volume	O
or	O
pitch	O
;	O
a	O
louder	O
or	O
higher-pitched	O
voice	O
requires	O
a	O
higher	O
rate	O
.	O
</s>
