<s>
and	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>
A	O
drawback	O
of	O
standard	O
SSB	B-Device
modulation	I-Device
is	O
the	O
generation	O
of	O
large	O
envelope	O
overshoots	O
well	O
above	O
the	O
average	O
envelope	O
level	O
for	O
a	O
sinusoidal	O
tone	O
(	O
even	O
when	O
the	O
audio	O
signal	O
is	O
peak-limited	O
)	O
.	O
</s>
<s>
The	O
standard	O
SSB	O
envelope	O
peaks	O
are	O
due	O
to	O
truncation	O
of	O
the	O
spectrum	O
and	O
nonlinear	O
phase	O
distortion	O
from	O
the	O
approximation	O
errors	O
of	O
the	O
practical	O
implementation	O
of	O
the	O
required	O
Hilbert	B-Algorithm
transform	I-Algorithm
.	O
</s>
<s>
It	O
was	O
recently	O
shown	O
that	O
suitable	O
overshoot	O
compensation	O
(	O
so-called	O
controlled-envelope	O
SSB	O
,	O
or	O
CESSB	B-Device
)	O
achieves	O
about	O
3.8dB	O
of	O
peak	O
reduction	O
for	O
speech	O
transmission	O
.	O
</s>
<s>
Although	O
the	O
generation	O
of	O
the	O
CESSB	B-Device
signal	O
can	O
be	O
integrated	O
into	O
the	O
SSB	O
modulator	B-Application
,	O
it	O
is	O
feasible	O
to	O
separate	O
the	O
generation	O
of	O
the	O
CESSB	B-Device
signal	O
(	O
e.g.	O
</s>
<s>
in	O
form	O
of	O
an	O
external	O
speech	O
preprocessor	O
)	O
from	O
a	O
conventional	O
SSB	B-Device
radio	I-Device
.	O
</s>
<s>
This	O
requires	O
that	O
the	O
SSB	B-Device
radio	I-Device
's	O
modulator	B-Application
be	O
linear-phase	O
and	O
have	O
a	O
sufficient	O
bandwidth	O
to	O
pass	O
the	O
CESSB	B-Device
signal	O
.	O
</s>
<s>
If	O
an	O
otherwise	O
conventional	O
SSB	O
modulator	B-Application
meets	O
these	O
requirements	O
,	O
then	O
the	O
envelope	O
control	O
by	O
the	O
CESSB	B-Device
process	O
is	O
preserved	O
.	O
</s>
<s>
CESSB	B-Device
is	O
being	O
used	O
experimentally	O
by	O
amateur	O
radio	O
operators	O
and	O
is	O
implemented	O
by	O
some	O
radios	O
in	O
the	O
amateur	O
marketplace	O
.	O
</s>
<s>
SmartSDR	O
software	O
by	O
Flex	O
Radio	O
Systems	O
implements	O
CESSB	B-Device
,	O
as	O
does	O
the	O
Elecraft	O
K4	O
transceiver	O
.	O
</s>
