<s>
Continuously	B-Algorithm
variable	I-Algorithm
slope	I-Algorithm
delta	I-Algorithm
modulation	I-Algorithm
(	O
CVSD	B-Algorithm
or	O
CVSDM	B-Algorithm
)	O
is	O
a	O
voice	B-Application
coding	I-Application
method	O
.	O
</s>
<s>
It	O
is	O
a	O
delta	B-General_Concept
modulation	I-General_Concept
with	O
variable	O
step	O
size	O
(	O
i.e.	O
,	O
special	O
case	O
of	O
adaptive	B-Algorithm
delta	I-Algorithm
modulation	I-Algorithm
)	O
,	O
first	O
proposed	O
by	O
Greefkes	O
and	O
Riemens	O
in	O
1970	O
.	O
</s>
<s>
CVSD	B-Algorithm
encodes	O
at	O
1	O
bit	O
per	O
sample	O
,	O
so	O
that	O
audio	O
sampled	O
at	O
16kHz	O
is	O
encoded	O
at	O
16kbit/s	O
.	O
</s>
<s>
Adaptation	O
of	O
step	O
size	O
allows	O
one	O
to	O
avoid	O
slope	O
overload	O
(	O
step	O
of	O
quantization	B-Algorithm
increases	O
when	O
the	O
signal	O
rapidly	O
changes	O
)	O
and	O
decreases	O
granular	O
noise	O
when	O
the	O
signal	O
is	O
constant	O
(	O
decrease	O
of	O
step	O
of	O
quantisation	B-Algorithm
)	O
.	O
</s>
<s>
CVSD	B-Algorithm
is	O
sometimes	O
called	O
a	O
compromise	O
between	O
simplicity	O
,	O
low	O
bitrate	O
,	O
and	O
quality	O
.	O
</s>
<s>
Like	O
other	O
delta-modulation	O
techniques	O
,	O
the	O
output	O
of	O
the	O
decoder	O
does	B-Algorithm
not	I-Algorithm
exactly	I-Algorithm
match	I-Algorithm
the	O
original	O
input	O
to	O
the	O
encoder	O
.	O
</s>
<s>
12kbit/s	O
CVSD	B-Algorithm
is	O
used	O
by	O
Motorola	O
's	O
SECURENET	O
line	O
of	O
digitally	O
encrypted	O
two-way	O
radio	O
products	O
.	O
</s>
<s>
16	O
and	O
32kbit/s	O
CVSD	B-Algorithm
were	O
used	O
by	O
military	O
TRI-TAC	O
digital	O
telephones	O
(	O
DNVT	O
,	O
DSVT	O
)	O
for	O
use	O
in	O
deployed	O
areas	O
to	O
provide	O
voice	O
recognition	O
quality	O
audio	O
.	O
</s>
<s>
16kbit/s	O
rates	O
were	O
typically	O
used	O
by	O
US	O
Army	O
forces	O
to	O
conserve	O
bandwidth	B-Algorithm
over	O
tactical	O
links	O
.	O
</s>
<s>
64kbit/s	O
CVSD	B-Algorithm
is	O
one	O
of	O
the	O
options	O
to	O
encode	O
voice	O
signals	O
in	O
telephony-related	O
Bluetooth	B-Protocol
service	O
profiles	O
;	O
e.g.	O
,	O
between	O
mobile	O
phones	O
and	O
wireless	O
headsets	O
.	O
</s>
<s>
The	O
other	O
options	O
are	O
PCM	B-Algorithm
with	O
logarithmic	O
a-law	B-Algorithm
or	O
μ-law	B-Algorithm
quantization	B-Algorithm
,	O
as	O
well	O
as	O
mSBC	O
codec	O
featuring	O
16	O
kHz	O
sample	O
rate	O
and	O
best	O
quality	O
.	O
</s>
<s>
Numerous	O
arcade	O
games	O
,	O
such	O
as	O
Sinistar	B-Application
and	O
Smash	B-Application
TV	I-Application
,	O
and	O
pinball	O
machines	O
,	O
such	O
as	O
Gorgar	O
or	O
Space	O
Shuttle	O
,	O
play	O
pre-recorded	O
speech	O
through	O
an	O
HC-55516	O
CVSD	B-Algorithm
decoder	O
.	O
</s>
<s>
Delta	B-General_Concept
modulation	I-General_Concept
was	O
used	O
by	O
Satellite	O
Business	O
Systems	O
or	O
SBS	O
for	O
its	O
voice	O
ports	O
to	O
provide	O
long-distance	O
phone	O
service	O
to	O
large	O
domestic	O
corporations	O
with	O
a	O
significant	O
inter-corporation	O
communications	O
need	O
(	O
such	O
as	O
IBM	O
)	O
.	O
</s>
<s>
The	O
voice	O
ports	O
used	O
digitally	O
implemented	O
24	O
kbit/s	O
delta	B-General_Concept
modulation	I-General_Concept
with	O
voice	O
activity	O
compression	O
(	O
VAC	O
)	O
and	O
echo	O
suppressors	O
to	O
control	O
the	O
half	O
second	O
echo	O
path	O
through	O
the	O
satellite	O
.	O
</s>
<s>
Listening	O
tests	O
were	O
conducted	O
to	O
verify	O
that	O
the	O
24	O
kbit/s	O
Delta	O
Modulator	O
achieved	O
"	O
full	O
voice	O
quality	O
"	O
with	O
no	O
discernible	O
degradation	O
as	O
compared	O
to	O
a	O
high	O
quality	O
phone	O
line	O
or	O
the	O
standard	O
64kbit/s	O
μ-law	B-Algorithm
companded	O
PCM	B-Algorithm
.	O
</s>
<s>
The	O
complete	O
function	O
of	O
delta	B-General_Concept
modulation	I-General_Concept
,	O
VAC	O
,	O
and	O
echo	O
control	O
for	O
6	O
ports	O
was	O
implemented	O
in	O
a	O
single	O
digital	O
integrated	O
circuit	O
chip	O
with	O
12-bit	O
arithmetic	O
.	O
</s>
