<s>
A	O
passband	B-Algorithm
is	O
the	O
range	O
of	O
frequencies	O
or	O
wavelengths	O
that	O
can	O
pass	O
through	O
a	O
filter	O
.	O
</s>
<s>
The	O
passband	B-Algorithm
of	O
a	O
receiver	O
is	O
the	O
range	O
of	O
frequencies	O
it	O
can	O
receive	O
when	O
it	O
is	O
tuned	O
into	O
the	O
desired	O
frequency	O
(	O
channel	O
)	O
.	O
</s>
<s>
A	O
bandpass-filtered	O
signal	O
(	O
that	O
is	O
,	O
a	O
signal	O
with	O
energy	O
only	O
in	O
a	O
passband	B-Algorithm
)	O
,	O
is	O
known	O
as	O
a	O
bandpass	B-Algorithm
signal	I-Algorithm
,	O
in	O
contrast	O
to	O
a	O
baseband	B-Algorithm
signal	I-Algorithm
.	O
</s>
<s>
In	O
telecommunications	O
,	O
optics	B-Algorithm
,	O
and	O
acoustics	O
,	O
a	O
passband	B-Algorithm
(	O
a	O
band-pass	O
filtered	O
signal	O
)	O
is	O
the	O
portion	O
of	O
the	O
frequency	O
spectrum	O
that	O
is	O
transmitted	O
(	O
with	O
minimum	O
relative	O
loss	O
or	O
maximum	O
relative	O
gain	O
)	O
by	O
some	O
filtering	O
device	O
.	O
</s>
<s>
The	O
accompanying	O
figure	O
shows	O
a	O
schematic	O
of	O
a	O
waveform	O
being	O
filtered	O
by	O
a	O
bandpass	O
filter	O
consisting	O
of	O
a	O
highpass	O
and	O
a	O
lowpass	B-Algorithm
filter	I-Algorithm
.	O
</s>
<s>
Radio	O
receivers	O
generally	O
include	O
a	O
tunable	O
band-pass	O
filter	O
with	O
a	O
passband	B-Algorithm
that	O
is	O
wide	O
enough	O
to	O
accommodate	O
the	O
bandwidth	B-Algorithm
of	O
the	O
radio	O
signal	O
transmitted	O
by	O
a	O
single	O
station	O
.	O
</s>
<s>
There	O
are	O
two	O
main	O
categories	O
of	O
digital	O
communication	O
transmission	O
methods	O
:	O
baseband	B-Algorithm
and	O
passband	B-Algorithm
.	O
</s>
<s>
In	O
baseband	B-Algorithm
transmission	I-Algorithm
,	O
line	B-Protocol
coding	I-Protocol
is	O
utilized	O
,	O
resulting	O
in	O
a	O
pulse	O
train	O
or	O
digital	O
pulse	B-Device
amplitude	I-Device
modulated	I-Device
(	O
PAM	O
)	O
signal	O
.	O
</s>
<s>
This	O
is	O
typically	O
used	O
over	O
non-filtered	O
wires	O
such	O
as	O
fiber	O
optical	O
cables	O
and	O
short-range	O
copper	O
links	O
,	O
for	O
example	O
:	O
V.29	O
(	O
EIA/TIA	O
-232	O
)	O
,	O
V.35	O
,	O
IEEE	O
802.3	O
,	O
SONET/SDH	B-Protocol
.	O
</s>
<s>
In	O
passband	B-Algorithm
transmission	O
,	O
digital	O
modulation	O
methods	O
are	O
employed	O
so	O
that	O
only	O
a	O
limited	O
frequency	O
range	O
is	O
used	O
in	O
some	O
bandpass	O
filtered	O
channel	O
.	O
</s>
<s>
Passband	B-Algorithm
transmission	O
is	O
typically	O
utilized	O
in	O
wireless	O
communication	O
and	O
in	O
bandpass	O
filtered	O
channels	O
such	O
as	O
POTS	B-Algorithm
lines	O
.	O
</s>
<s>
It	O
also	O
allows	O
for	O
frequency-division	B-Protocol
multiplexing	I-Protocol
.	O
</s>
<s>
The	O
digital	O
bitstream	O
is	O
converted	O
first	O
into	O
an	O
equivalent	B-Algorithm
baseband	I-Algorithm
signal	I-Algorithm
,	O
and	O
then	O
to	O
a	O
RF	O
signal	O
.	O
</s>
<s>
On	O
the	O
receiver	O
side	O
a	O
demodulator	B-Device
is	O
used	O
to	O
detect	O
the	O
signal	O
and	O
reverse	O
the	O
modulation	O
process	O
.	O
</s>
<s>
A	O
combined	O
equipment	O
for	O
modulation	O
and	O
demodulation	B-Device
is	O
called	O
a	O
modem	B-Application
.	O
</s>
<s>
In	O
general	O
,	O
there	O
is	O
an	O
inverse	O
relationship	O
between	O
the	O
width	O
of	O
a	O
filter	O
's	O
passband	B-Algorithm
and	O
the	O
time	O
required	O
for	O
the	O
filter	O
to	O
respond	O
to	O
new	O
inputs	O
.	O
</s>
<s>
Broad	O
passbands	B-Algorithm
yield	O
faster	O
response	O
times	O
.	O
</s>
<s>
The	O
limiting	O
frequencies	O
of	O
a	O
passband	B-Algorithm
are	O
defined	O
as	O
those	O
at	O
which	O
the	O
relative	O
intensity	O
or	O
power	O
decreases	O
to	O
a	O
specified	O
fraction	O
of	O
the	O
maximum	O
intensity	O
or	O
power	O
.	O
</s>
<s>
The	O
difference	O
between	O
the	O
limiting	O
frequencies	O
is	O
called	O
the	O
bandwidth	B-Algorithm
,	O
and	O
is	O
expressed	O
in	O
hertz	O
(	O
in	O
the	O
optical	O
regime	O
,	O
in	O
nanometers	O
or	O
micrometers	O
of	O
differential	O
wavelength	O
)	O
.	O
</s>
<s>
The	O
related	O
term	O
"	O
bandpass	O
"	O
is	O
an	O
adjective	O
that	O
describes	O
a	O
type	O
of	O
filter	O
or	O
filtering	O
process	O
;	O
it	O
is	O
frequently	O
confused	O
with	O
"	O
passband	B-Algorithm
"	O
,	O
which	O
refers	O
to	O
the	O
actual	O
portion	O
of	O
affected	O
spectrum	O
.	O
</s>
<s>
Hence	O
,	O
one	O
may	O
correctly	O
say	O
'	O
A	O
dual	O
bandpass	O
filter	O
has	O
two	O
passbands	B-Algorithm
 '	O
.	O
</s>
