<s>
Amplitude-companded	O
single-sideband	B-Device
(	O
ACSB	B-Device
)	O
is	O
a	O
narrowband	O
modulation	B-Application
method	O
using	O
a	O
single-sideband	B-Device
with	O
a	O
pilot	O
tone	O
,	O
allowing	O
an	O
expander	O
in	O
the	O
receiver	O
to	O
restore	O
the	O
amplitude	B-Application
that	O
was	O
severely	O
compressed	O
by	O
the	O
transmitter	O
.	O
</s>
<s>
The	O
pilot	O
tone	O
serves	O
as	O
a	O
frequency	O
reference	O
for	O
the	O
receiver	O
,	O
eliminating	O
the	O
signal	O
distortion	O
that	O
would	O
occur	O
with	O
single-sideband	B-Device
suppressed	O
carrier	O
modulation	B-Application
when	O
the	O
receiver	O
is	O
off	O
frequency	O
.	O
</s>
<s>
It	O
offers	O
improved	O
effective	O
range	O
over	O
standard	O
SSB	B-Device
modulation	I-Device
while	O
simultaneously	O
retaining	O
backwards	O
compatibility	O
with	O
standard	O
SSB	B-Device
radios	I-Device
.	O
</s>
<s>
ACSB	B-Device
also	O
offers	O
reduced	O
bandwidth	B-Algorithm
and	O
improved	O
range	O
for	O
a	O
given	O
power	O
level	O
compared	O
with	O
narrow	O
band	O
FM	B-Algorithm
modulation	B-Application
.	O
</s>
<s>
The	O
companding	O
used	O
in	O
ACSB	B-Device
is	O
a	O
type	O
of	O
dynamic	O
range	O
reduction	O
wherein	O
the	O
difference	O
in	O
amplitude	B-Application
between	O
the	O
louder	O
and	O
softer	O
sounds	O
is	O
reduced	O
prior	O
to	O
transmission	O
.	O
</s>
<s>
If	O
a	O
conventional	O
SSB	O
receiver	O
is	O
used	O
to	O
receive	O
ACSB	B-Device
signals	O
,	O
some	O
distortion	O
may	O
be	O
noticed	O
but	O
generally	O
the	O
signals	O
are	O
quite	O
intelligible	O
.	O
</s>
<s>
ACSB	B-Device
is	O
being	O
used	O
by	O
amateur	O
radio	O
operators	O
,	O
air-to-ground	B-Application
phones	I-Application
,	O
as	O
well	O
as	O
mobile-satellite	O
services	O
.	O
</s>
