<s>
8VSB	B-Device
is	O
the	O
modulation	B-Application
method	O
used	O
for	O
broadcast	O
in	O
the	B-Device
ATSC	I-Device
digital	B-Application
television	I-Application
standard	O
.	O
</s>
<s>
ATSC	B-Device
and	O
8VSB	B-Device
modulation	B-Application
is	O
used	O
primarily	O
in	O
North	O
America	O
;	O
in	O
contrast	O
,	O
the	O
DVB-T	O
standard	O
uses	O
COFDM	B-Protocol
.	O
</s>
<s>
A	O
modulation	B-Application
method	O
specifies	O
how	O
the	O
radio	O
signal	O
fluctuates	O
to	O
convey	O
information	O
.	O
</s>
<s>
ATSC	B-Device
and	O
DVB-T	O
specify	O
the	O
modulation	B-Application
used	O
for	O
over-the-air	O
digital	B-Application
television	I-Application
;	O
by	O
comparison	O
,	O
QAM	B-Device
is	O
the	O
modulation	B-Application
method	O
used	O
for	O
cable	O
.	O
</s>
<s>
The	O
specifications	O
for	O
a	O
cable-ready	O
television	O
,	O
then	O
,	O
might	O
state	O
that	O
it	O
supports	O
8VSB	B-Device
(	O
for	O
broadcast	O
TV	O
)	O
and	O
QAM	B-Device
(	O
for	O
cable	O
TV	O
)	O
.	O
</s>
<s>
8VSB	B-Device
is	O
an	O
8-level	O
vestigial	O
sideband	O
modulation	B-Application
.	O
</s>
<s>
8VSB	B-Device
is	O
capable	O
of	O
transmitting	O
three	O
bits	O
(	O
23	O
=	O
8	O
)	O
per	O
symbol	O
;	O
in	O
ATSC	B-Device
,	O
each	O
symbol	O
includes	O
two	O
bits	O
from	O
the	O
MPEG	O
transport	O
stream	O
which	O
are	O
trellis	O
modulated	B-Application
to	O
produce	O
a	O
three-bit	O
figure	O
.	O
</s>
<s>
The	O
resulting	O
signal	O
is	O
then	O
band-pass	O
filtered	O
with	O
a	O
Nyquist	B-Algorithm
filter	I-Algorithm
to	O
remove	O
redundancies	O
in	O
the	O
side	O
lobes	O
,	O
and	O
then	O
shifted	O
up	O
to	O
the	O
broadcast	O
frequency	O
.	O
</s>
<s>
Vestigial	O
sideband	O
modulation	B-Application
(	O
VSB	O
)	O
is	O
a	O
modulation	B-Application
method	O
which	O
attempts	O
to	O
eliminate	O
the	O
spectral	O
redundancy	O
of	O
pulse-amplitude	B-Device
modulation	I-Device
(	O
PAM	O
)	O
signals	O
.	O
</s>
<s>
In	O
the	O
6MHz	O
(	O
megahertz	O
)	O
channel	O
used	O
for	O
broadcast	O
ATSC	B-Device
,	O
8VSB	B-Device
carries	O
a	O
symbol	O
rate	O
of	O
10.76	O
megabaud	O
,	O
a	O
gross	O
bit	O
rate	O
of	O
32	O
Mbit/s	O
,	O
and	O
a	O
net	O
bit	O
rate	O
of	O
19.39	O
Mbit/s	O
of	O
usable	O
data	O
.	O
</s>
<s>
The	O
net	O
bit	O
rate	O
is	O
lower	O
due	O
to	O
the	O
addition	O
of	O
forward	B-Error_Name
error	I-Error_Name
correction	I-Error_Name
codes	O
.	O
</s>
<s>
There	O
are	O
also	O
similar	O
modulations	B-Application
2VSB	B-Device
,	O
4VSB	B-Device
,	O
and	O
16VSB	B-Device
.	O
</s>
<s>
16VSB	B-Device
was	O
notably	O
intended	O
to	O
be	O
used	O
for	O
ATSC	B-Device
digital	B-Device
cable	I-Device
,	O
but	O
quadrature	B-Device
amplitude	I-Device
modulation	I-Device
(	O
QAM	B-Device
)	O
has	O
become	O
the	O
de	O
facto	O
industry	O
standard	O
instead	O
as	O
it	O
is	O
cheap	O
and	O
readily	O
available	O
.	O
</s>
<s>
A	O
significant	O
advantage	O
of	O
8VSB	B-Device
for	O
broadcasters	O
is	O
that	O
it	O
requires	O
much	O
less	O
power	O
to	O
cover	O
an	O
area	O
comparable	O
to	O
that	O
of	O
the	O
earlier	O
NTSC	O
system	O
,	O
and	O
it	O
is	O
reportedly	O
better	O
at	O
this	O
than	O
the	O
most	O
common	O
alternative	O
system	O
,	O
COFDM	B-Protocol
.	O
</s>
<s>
Part	O
of	O
the	O
advantage	O
is	O
the	O
lower	O
peak	O
to	O
average	O
power	O
ratio	O
needed	O
compared	O
to	O
COFDM	B-Protocol
.	O
</s>
<s>
An	O
8VSB	B-Device
transmitter	O
needs	O
to	O
have	O
a	O
peak	O
power	O
capability	O
of	O
6db	O
(	O
four	O
times	O
)	O
its	O
average	O
power	O
.	O
</s>
<s>
8VSB	B-Device
is	O
also	O
more	O
resistant	O
to	O
impulse	O
noise	O
.	O
</s>
<s>
While	O
NTSC	O
and	O
most	O
other	O
analog	O
television	O
systems	O
also	O
use	O
a	O
vestigial	O
sideband	O
technique	O
,	O
the	O
unwanted	O
sideband	O
is	O
filtered	O
much	O
more	O
effectively	O
in	O
ATSC	B-Device
8VSB	B-Device
transmissions	O
.	O
</s>
<s>
8VSB	B-Device
uses	O
a	O
Nyquist	B-Algorithm
filter	I-Algorithm
to	O
achieve	O
this	O
.	O
</s>
<s>
Reed	B-Error_Name
–	I-Error_Name
Solomon	I-Error_Name
error	I-Error_Name
correction	I-Error_Name
is	O
the	O
primary	O
system	O
used	O
to	O
retain	O
data	O
integrity	O
.	O
</s>
<s>
In	O
summer	O
of	O
2005	O
,	O
the	B-Device
ATSC	I-Device
published	O
standards	O
for	O
Enhanced	O
VSB	O
,	O
or	O
E-VSB	B-Device
.	O
</s>
<s>
Using	O
forward	B-Error_Name
error	I-Error_Name
correction	I-Error_Name
,	O
the	O
E-VSB	B-Device
standard	O
will	O
allow	O
DTV	B-Application
reception	O
on	O
low	O
power	O
handheld	O
receivers	O
with	O
smaller	O
antennas	O
in	O
much	O
the	O
same	O
way	O
DVB-H	B-Protocol
does	O
in	O
Europe	O
,	O
but	O
still	O
using	O
8VSB	B-Device
transmission	O
.	O
</s>
<s>
For	O
some	O
period	O
of	O
time	O
,	O
there	O
had	O
been	O
a	O
continuing	O
lobby	O
for	O
changing	O
the	O
modulation	B-Application
for	O
ATSC	B-Device
to	O
COFDM	B-Protocol
,	O
the	O
way	O
DVB-T	O
is	O
transmitted	O
in	O
Europe	O
,	O
and	O
ISDB-T	O
in	O
Japan	O
.	O
</s>
<s>
However	O
,	O
the	O
FCC	O
has	O
always	O
held	O
that	O
8VSB	B-Device
is	O
the	O
better	O
modulation	B-Application
for	O
use	O
in	O
U.S.	O
digital	B-Application
television	I-Application
broadcasting	O
.	O
</s>
<s>
In	O
a	O
1999	O
report	O
,	O
the	O
Commission	O
found	O
that	O
8VSB	B-Device
has	O
better	O
threshold	O
or	O
carrier-to-noise	O
(	O
C/N	O
)	O
performance	O
,	O
has	O
a	O
higher	O
data	O
rate	O
capability	O
,	O
requires	O
less	O
transmitter	O
power	O
for	O
equivalent	O
coverage	O
,	O
and	O
is	O
more	O
robust	O
to	O
impulse	O
and	O
phase	O
noise	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
it	O
denied	O
in	O
2000	O
a	O
petition	O
for	O
rulemaking	O
from	O
Sinclair	O
Broadcast	O
Group	O
requesting	O
that	O
broadcasters	O
be	O
allowed	O
to	O
choose	O
between	O
8VSB	B-Device
or	O
COFDM	B-Protocol
as	O
is	O
most	O
appropriate	O
for	O
their	O
area	O
of	O
coverage	O
.	O
</s>
<s>
The	O
FCC	O
report	O
also	O
acknowledged	O
that	O
COFDM	B-Protocol
would	O
"	O
generally	O
be	O
expected	O
to	O
perform	O
better	O
in	O
situations	O
where	O
there	O
is	O
dynamic	O
multipath	O
,	O
"	O
such	O
as	O
mobile	O
operation	O
or	O
in	O
the	O
presence	O
of	O
trees	O
that	O
are	O
moving	O
in	O
high	O
winds	O
.	O
</s>
<s>
However	O
,	O
with	O
the	O
introduction	O
of	O
5th	O
Generation	O
demodulators	O
in	O
2005	O
and	O
subsequent	O
improvements	O
in	O
generations	O
6	O
and	O
7	O
,	O
the	O
equalization	O
span	O
is	O
now	O
about	O
−60	O
to	O
+75	O
microseconds	O
(	O
a	O
135	O
microsecond	O
spread	O
)	O
and	O
has	O
virtually	O
eliminated	O
multipath	O
,	O
both	O
static	O
and	O
dynamic	O
,	O
in	O
8VSB	B-Device
reception	O
.	O
</s>
<s>
In	O
comparison	O
,	O
the	O
equalization	O
span	O
in	O
COFDM	B-Protocol
is	O
−100	O
to	O
+100	O
microseconds	O
(	O
200	O
microsecond	O
spread	O
)	O
,	O
but	O
the	O
application	O
of	O
this	O
much	O
guard	O
band	O
space	O
for	O
COFDM	B-Protocol
substantially	O
reduces	O
its	O
useful	O
payload	O
.	O
</s>
<s>
1920×1080i	O
has	O
always	O
been	O
part	O
of	O
the	O
8VSB	B-Device
scheme	O
from	O
its	O
inception	O
,	O
and	O
its	O
improved	O
demodulators	O
have	O
had	O
no	O
effect	O
on	O
its	O
innate	O
payload	O
capacity	O
.	O
</s>
<s>
Because	O
of	O
continued	O
adoption	O
of	O
the	O
8VSB-based	O
ATSC	B-Device
standard	I-Device
in	O
the	O
U.S.	O
,	O
and	O
a	O
large	O
growing	O
ATSC	B-Device
receiver	I-Device
population	O
,	O
a	O
switch	O
to	O
COFDM	B-Protocol
will	O
be	O
challenging	O
.	O
</s>
<s>
Most	O
analog	O
terrestrial	O
transmissions	O
in	O
the	O
US	O
were	O
turned	O
off	O
in	O
June	O
2009	O
,	O
and	O
8VSB	B-Device
tuners	O
are	O
common	O
to	O
all	O
new	O
TVs	O
,	O
further	O
complicating	O
a	O
future	O
transition	O
to	O
COFDM	B-Protocol
.	O
</s>
<s>
However	O
,	O
with	O
the	O
development	O
of	O
ATSC	B-Device
3.0	I-Device
,	O
an	O
updated	O
version	O
of	O
the	O
American	O
digital	B-Application
television	I-Application
standard	O
designed	O
for	O
mobile	O
reception	O
and	O
better	O
single	O
frequency	O
network	O
performance	O
,	O
the	B-Device
ATSC	I-Device
has	O
decided	O
to	O
make	O
the	O
switch	O
to	O
OFDM	B-Protocol
with	O
LDPC	B-Error_Name
error	O
correction	O
(	O
essentially	O
COFDM	B-Protocol
)	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
ATSC	B-Device
3.0	I-Device
will	O
be	O
incompatible	O
with	O
all	O
current	O
ATSC	B-Device
1.0	I-Device
receivers	O
,	O
and	O
viewers	O
will	O
need	O
a	O
new	O
TV	O
with	O
a	O
compatible	O
tuner	O
or	O
a	O
converter	O
box	O
.	O
</s>
<s>
Unlike	O
the	O
previous	O
digital	B-Application
TV	I-Application
transition	O
which	O
was	O
mandated	O
by	O
the	O
FCC	O
,	O
the	O
"	O
transition	O
"	O
to	O
ATSC	B-Device
3.0	I-Device
will	O
be	O
completely	O
voluntary	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
FCC	O
has	O
required	O
that	O
broadcasters	O
who	O
decided	O
to	O
make	O
the	O
switch	O
to	O
ATSC	B-Device
3.0	I-Device
continue	O
to	O
make	O
their	O
main	O
channel	O
available	O
through	O
a	O
simulcast	O
agreement	O
with	O
another	O
in-market	O
station	O
(	O
with	O
a	O
similar	O
coverage	O
area	O
)	O
through	O
at	O
least	O
2022	O
.	O
</s>
<s>
Sinclair	O
announced	O
an	O
intention	O
to	O
bring	O
ATSC	B-Device
3.0	I-Device
to	O
40	O
cities	O
by	O
2020	O
.	O
</s>
<s>
The	O
previously	O
cited	O
FCC	O
Report	O
also	O
found	O
that	O
COFDM	B-Protocol
has	O
better	O
performance	O
in	O
dynamic	O
and	O
high	O
level	O
static	O
multipath	O
situations	O
,	O
and	O
offers	O
advantages	O
for	O
single	O
frequency	O
networks	O
and	O
mobile	O
reception	O
.	O
</s>
<s>
Nonetheless	O
,	O
in	O
2001	O
,	O
a	O
technical	O
report	O
compiled	O
by	O
the	O
COFDM	B-Protocol
Technical	O
Group	O
concluded	O
that	O
COFDM	B-Protocol
did	O
not	O
offer	O
any	O
significant	O
advantages	O
over	O
8VSB	B-Device
.	O
</s>
<s>
Neither	O
8VSB	B-Device
nor	O
COFDM	B-Protocol
performed	O
acceptably	O
in	O
most	O
indoor	O
test	O
installations	O
.	O
</s>
<s>
However	O
,	O
there	O
were	O
questions	O
whether	O
the	O
COFDM	B-Protocol
receiver	O
selected	O
for	O
these	O
tests	O
−	O
a	O
transmitter	O
monitor	O
lacking	O
normal	O
front	O
end	O
filtering	O
−	O
colored	O
these	O
results	O
.	O
</s>
<s>
Retests	O
that	O
were	O
performed	O
using	O
the	O
same	O
COFDM	B-Protocol
receivers	O
with	O
the	O
addition	O
of	O
a	O
front	O
end	O
band	O
pass	O
filter	O
gave	O
much	O
improved	O
results	O
for	O
the	O
DVB-T	O
receiver	O
,	O
but	O
further	O
testing	O
was	O
not	O
pursued	O
.	O
</s>
<s>
The	O
debate	O
over	O
8VSB	B-Device
versus	O
COFDM	B-Protocol
modulation	B-Application
is	O
still	O
ongoing	O
.	O
</s>
<s>
Proponents	O
of	O
COFDM	B-Protocol
argue	O
that	O
it	O
resists	O
multipath	O
far	O
better	O
than	O
8VSB	B-Device
.	O
</s>
<s>
This	O
is	O
important	O
property	O
of	O
the	O
modulation	B-Application
for	O
receiving	O
HDTV	O
in	O
e.g.	O
</s>
<s>
moving	O
vehicles	O
that	O
is	O
not	O
possible	O
with	O
8VSB	B-Device
.	O
</s>
<s>
Early	O
8VSB	B-Device
DTV	B-Application
(	O
digital	B-Application
television	I-Application
)	O
receivers	O
often	O
had	O
difficulty	O
receiving	O
a	O
signal	O
in	O
urban	O
environments	O
.	O
</s>
<s>
Newer	O
8VSB	B-Device
receivers	O
,	O
however	O
,	O
are	O
better	O
at	O
dealing	O
with	O
multipath	O
,	O
but	O
a	O
moving	O
receiver	O
can	O
still	O
not	O
receive	O
the	O
signal	O
.	O
</s>
<s>
Moreover	O
,	O
8VSB	B-Device
modulation	B-Application
requires	O
less	O
power	O
to	O
transmit	O
a	O
signal	O
the	O
same	O
distance	O
.	O
</s>
<s>
In	O
less	O
populated	O
areas	O
,	O
8VSB	B-Device
may	O
outperform	O
COFDM	B-Protocol
because	O
of	O
this	O
.	O
</s>
<s>
However	O
,	O
in	O
some	O
urban	O
areas	O
,	O
as	O
well	O
as	O
for	O
mobile	O
use	O
,	O
COFDM	B-Protocol
may	O
offer	O
better	O
reception	O
than	O
8VSB	B-Device
.	O
</s>
<s>
Several	O
"	O
enhanced	O
"	O
VSB	O
systems	O
were	O
in	O
development	O
,	O
most	O
notably	O
E-VSB	B-Device
,	O
A-VSB	B-Device
,	O
and	O
MPH	B-Device
.	O
</s>
<s>
The	O
deficiencies	O
in	O
8VSB	B-Device
in	O
regards	O
to	O
multipath	O
reception	O
can	O
be	O
dealt	O
with	O
by	O
using	O
additional	O
forward	O
error-correcting	O
codes	O
which	O
decreases	O
the	O
useful	O
bit	O
rate	O
,	O
such	O
as	O
that	O
used	O
by	O
ATSC-M/H	B-Device
for	O
Mobile/Handheld	O
reception	O
.	O
</s>
<s>
ATSC	B-Device
3.0	I-Device
,	O
the	O
next	O
major	O
television	O
standard	O
in	O
the	O
United	O
States	O
,	O
will	O
use	O
COFDM	B-Protocol
.	O
</s>
<s>
The	O
vast	O
majority	O
of	O
U.S.	O
TV	O
stations	O
use	O
COFDM	B-Protocol
for	O
their	O
studio	O
to	O
transmitter	O
links	O
and	O
news	O
gathering	O
operations	O
.	O
</s>
