<s>
A	O
multiplex	B-Device
or	O
mux	O
(	O
called	O
virtual	B-Protocol
sub-channel	O
in	O
the	O
United	O
States	O
and	O
Canada	O
,	O
and	O
bouquet	O
in	O
France	O
)	O
is	O
a	O
grouping	O
of	O
program	O
services	O
as	O
interleaved	O
data	O
packets	O
for	O
broadcast	O
over	O
a	O
network	O
or	O
modulated	O
multiplexed	O
medium	O
.	O
</s>
<s>
In	O
the	O
United	O
Kingdom	O
,	O
a	O
terrestrial	O
multiplex	B-Device
(	O
usually	O
abbreviated	O
mux	O
)	O
has	O
a	O
fixed	O
bandwidth	O
of	O
8	O
MHz	O
CODFM	B-Protocol
of	O
interleaved	O
H.222	O
packets	O
containing	O
a	O
number	O
of	O
channels	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
a	O
similar	O
arrangement	O
using	O
6	O
MHz	O
8VSB	B-Device
is	O
often	O
described	O
as	O
a	O
channel	O
with	O
virtual	B-Protocol
sub-channels	O
.	O
</s>
<s>
In	O
regards	O
to	O
television	O
,	O
the	O
term	O
multiplex	B-Device
is	O
often	O
used	O
to	O
refer	O
to	O
a	O
single	O
broadcaster	O
offering	O
multiple	O
channels	O
of	O
programming	O
as	O
a	O
single	O
bundle	O
to	O
its	O
subscribers	O
.	O
</s>
<s>
The	O
term	O
is	O
most	O
synonymous	O
with	O
premium	O
television	O
services	O
,	O
such	O
as	O
those	O
devoted	O
to	O
films	O
(	O
where	O
the	O
term	O
evokes	O
the	O
symbolism	O
of	O
multiplex	B-Device
cinemas	O
)	O
or	O
sports	O
;	O
for	O
instance	O
,	O
film	O
services	O
may	O
operate	O
multiplex	B-Device
channels	O
devoted	O
to	O
specific	O
genres	O
and	O
traits	O
(	O
such	O
as	O
action	O
,	O
classic	O
,	O
comedy	O
,	O
drama	O
and	O
romance	O
,	O
or	O
family	O
films	O
)	O
alongside	O
their	O
primary	O
flagship	O
channel	O
,	O
while	O
sports	O
services	O
may	O
place	O
specific	O
events	O
or	O
sports	O
on	O
specific	O
channels	O
.	O
</s>
<s>
Multiplex	B-Device
channels	O
are	O
not	O
necessarily	O
sold	O
separately	O
on	O
an	O
a	O
la	O
carte	O
basis	O
from	O
their	O
parent	O
and	O
sister	O
channels	O
.	O
</s>
<s>
Digital	B-Application
television	I-Application
channels	O
can	O
be	O
interleaved	O
and	O
are	O
in	O
a	O
highly	O
compressed	O
format	O
,	O
so	O
that	O
the	O
bandwidth	O
they	O
require	O
varies	O
due	O
to	O
the	O
bitrate	O
provided	O
to	O
each	O
channel	O
;	O
it	O
is	O
more	O
cost	O
efficient	O
to	O
transmit	O
several	O
channels	O
together	O
so	O
that	O
they	O
share	O
the	O
same	O
bandwidth	O
,	O
each	O
channel	O
has	O
carefully	O
constrained	O
bitrates	O
allocated	O
,	O
so	O
that	O
the	O
sum	O
of	O
all	O
channels	O
fill	O
the	O
fixed	O
bandwidth	O
provided	O
.	O
</s>
<s>
A	O
group	O
of	O
program	O
services	O
transmitted	O
within	O
a	O
particular	O
bandwidth	O
allocation	O
is	O
erroneously	O
known	O
as	O
a	O
multiplex	B-Device
;	O
or	O
the	O
channels	O
may	O
be	O
called	O
subchannels	B-Device
.	O
</s>
<s>
A	O
set-top	O
box	O
or	O
integrated	B-Device
digital	I-Device
television	I-Device
is	O
required	O
to	O
tune	O
in	O
,	O
receive	O
,	O
and	O
split	O
a	O
channel	O
for	O
viewing	O
.	O
</s>
<s>
Digital	B-Application
television	I-Application
transports	O
vary	O
in	O
the	O
number	O
of	O
channels	O
that	O
can	O
be	O
transmitted	O
,	O
based	O
on	O
the	O
bandwidth	O
of	O
the	O
multiplex	B-Device
and	O
the	O
broadcast	O
quality	O
specified	O
for	O
each	O
channel	O
.	O
</s>
<s>
Digital	O
terrestrial	O
offers	O
the	O
least	O
,	O
digital	B-Device
cable	I-Device
and	O
satellite	O
the	O
most	O
bandwidth	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
the	O
standard	O
for	O
over-the-air	O
digital	O
transmissions	O
is	O
ATSC	B-Device
,	O
digital	B-Device
cable	I-Device
is	O
based	O
on	O
the	O
worldwide	O
DVB	O
standard	O
,	O
DVB-C	B-Device
(	O
"	O
C	O
"	O
for	O
cable	O
)	O
and	O
transmission	O
via	O
satellite	O
are	O
based	O
on	O
the	O
DVB-S	O
(	O
"	O
S	O
"	O
for	O
satellite	O
)	O
standard	O
,	O
all	O
use	O
multiplexes	B-Device
to	O
deliver	O
various	O
channels	O
to	O
the	O
viewer	O
.	O
</s>
<s>
Smaller	O
and	O
newer	O
commercial	O
networks	O
,	O
such	O
as	O
The	O
CW	O
and	O
MyNetworkTV	O
,	O
are	O
available	O
in	O
some	O
markets	O
as	O
digital	B-Device
subchannels	I-Device
of	O
stations	O
affiliated	O
with	O
other	O
networks	O
rather	O
than	O
as	O
standalone	O
stations	O
.	O
</s>
<s>
A	O
typical	O
American	O
ATSC	B-Device
transport	O
offers	O
three	O
to	O
four	O
channels	O
;	O
in	O
most	O
cases	O
one	O
of	O
them	O
is	O
broadcast	O
in	O
HD	O
(	O
the	O
station	O
's	O
main	O
channel	O
)	O
and	O
the	O
rest	O
of	O
the	O
channels	O
are	O
broadcast	O
in	O
standard	B-Device
definition	I-Device
,	O
due	O
to	O
the	O
limited	O
6	O
MHz	O
8VSB	B-Device
bandwidth	O
used	O
.	O
</s>
<s>
In	O
those	O
cases	O
when	O
one	O
physical	O
channel	O
transports	O
more	O
than	O
one	O
HD	O
sub-channel	O
,	O
the	O
data	O
rate	O
drops	O
to	O
the	O
level	O
of	O
standard	B-Device
definition	I-Device
DVD-Video	O
.	O
</s>
<s>
The	O
corresponding	O
image	O
degradation	O
manifests	O
itself	O
in	O
reduced	O
resolution	O
,	O
increased	O
noise	O
and	O
compression	B-Algorithm
artifacts	I-Algorithm
.	O
</s>
<s>
For	O
example	O
,	O
KPBS	O
broadcasts	O
four	O
multiplexes	B-Device
on	O
a	O
single	O
physical	O
channel	O
,	O
two	O
of	O
which	O
are	O
HD	O
.	O
</s>
<s>
In	O
Europe	O
,	O
transports	O
are	O
used	O
on	O
CODFM	B-Protocol
64-QAM/256	O
-QAM	O
modulated	O
DVB-T	O
and	O
DVB-T2	B-Protocol
(	O
"	O
T	O
"	O
for	O
terrestrial	O
)	O
digital	O
terrestrial	O
standards	O
,	O
on	O
CODFM	B-Protocol
256-QAM	O
modulated	O
DVB-C	B-Device
digital	B-Device
cable	I-Device
and	O
on	O
CODFM	B-Protocol
QPSK/8PSK	O
modulated	O
DVB-S	O
digital	O
satellite	O
.	O
</s>
<s>
A	O
typical	O
DVB-T	O
transport	O
in	O
Europe	O
offers	O
four	O
or	O
more	O
standard	B-Device
definition	I-Device
channels	O
transmitted	O
simultaneously	O
;	O
if	O
some	O
channels	O
transmit	O
only	O
for	O
part	O
of	O
the	O
day	O
(	O
for	O
example	O
,	O
a	O
children	O
's	O
channel	O
during	O
daytime	O
,	O
a	O
channel	O
with	O
programs	O
for	O
adults	O
in	O
the	O
evening	O
)	O
,	O
many	O
channels	O
may	O
share	O
the	O
same	O
transport	O
.	O
</s>
