<s>
In	O
coding	B-Error_Name
theory	I-Error_Name
,	O
the	O
repetition	B-Error_Name
code	I-Error_Name
is	O
one	O
of	O
the	O
most	O
basic	O
linear	O
error-correcting	B-Error_Name
codes	I-Error_Name
.	O
</s>
<s>
In	O
order	O
to	O
transmit	O
a	O
message	O
over	O
a	O
noisy	O
channel	O
that	O
may	O
corrupt	O
the	O
transmission	O
in	O
a	O
few	O
places	O
,	O
the	O
idea	O
of	O
the	O
repetition	B-Error_Name
code	I-Error_Name
is	O
to	O
just	O
repeat	O
the	O
message	O
several	O
times	O
.	O
</s>
<s>
Because	O
of	O
the	O
bad	O
error	O
correcting	O
performance	O
coupled	O
with	O
the	O
low	O
code	O
rate	O
(	O
ratio	O
between	O
useful	O
information	O
symbols	O
and	O
actual	O
transmitted	O
symbols	O
)	O
,	O
other	O
error	B-Error_Name
correction	I-Error_Name
codes	I-Error_Name
are	O
preferred	O
in	O
most	O
cases	O
.	O
</s>
<s>
The	O
chief	O
attraction	O
of	O
the	O
repetition	B-Error_Name
code	I-Error_Name
is	O
the	O
ease	O
of	O
implementation	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
a	O
binary	O
repetition	B-Error_Name
code	I-Error_Name
,	O
there	O
exist	O
two	O
code	O
words	O
-	O
all	O
ones	O
and	O
all	O
zeros	O
-	O
which	O
have	O
a	O
length	O
of	O
.	O
</s>
<s>
This	O
gives	O
the	O
repetition	B-Error_Name
code	I-Error_Name
an	O
error	O
correcting	O
capacity	O
of	O
(	O
i.e.	O
</s>
<s>
If	O
the	O
length	O
of	O
a	O
binary	O
repetition	B-Error_Name
code	I-Error_Name
is	O
odd	O
,	O
then	O
it	O
's	O
a	O
perfect	O
code	O
.	O
</s>
<s>
The	O
binary	O
repetition	B-Error_Name
code	I-Error_Name
of	O
length	O
n	O
is	O
equivalent	O
to	O
the	O
(	O
n	O
,	O
1	O
)	O
-Hamming	O
code	O
.	O
</s>
<s>
Consider	O
a	O
binary	O
repetition	B-Error_Name
code	I-Error_Name
of	O
length	O
3	O
.	O
</s>
<s>
Decoding	O
is	O
usually	O
done	O
by	O
a	O
simple	O
majority	B-Error_Name
decision	I-Error_Name
for	O
each	O
code	O
word	O
.	O
</s>
<s>
Despite	O
their	O
poor	O
performance	O
as	O
stand-alone	O
codes	O
,	O
use	O
in	O
Turbo	O
code-like	O
iteratively	O
decoded	O
concatenated	O
coding	O
schemes	O
,	O
such	O
as	O
repeat-accumulate	B-Error_Name
(	O
RA	O
)	O
and	O
accumulate-repeat-accumulate	O
(	O
ARA	O
)	O
codes	O
,	O
allows	O
for	O
surprisingly	O
good	O
error	O
correction	O
performance	O
.	O
</s>
<s>
Repetition	B-Error_Name
codes	I-Error_Name
are	O
one	O
of	O
the	O
few	O
known	O
codes	O
whose	O
code	O
rate	O
can	O
be	O
automatically	O
adjusted	O
to	O
varying	O
channel	O
capacity	O
,	O
by	O
sending	O
more	O
or	O
less	O
parity	O
information	O
as	O
required	O
to	O
overcome	O
the	O
channel	O
noise	O
,	O
and	O
it	O
is	O
the	O
only	O
such	O
code	O
known	O
for	O
non-erasure	O
channels	O
.	O
</s>
<s>
Practical	O
adaptive	O
codes	O
for	O
erasure	O
channels	O
have	O
been	O
invented	O
only	O
recently	O
,	O
and	O
are	O
known	O
as	O
fountain	B-Error_Name
codes	I-Error_Name
.	O
</s>
<s>
Some	O
UARTs	O
,	O
such	O
as	O
the	O
ones	O
used	O
in	O
the	O
FlexRay	B-Protocol
protocol	O
,	O
use	O
a	O
majority	O
filter	O
to	O
ignore	O
brief	O
noise	O
spikes	O
.	O
</s>
