<s>
An	O
optical	B-Protocol
time-domain	I-Protocol
reflectometer	I-Protocol
(	O
OTDR	B-Protocol
)	O
is	O
an	O
optoelectronic	O
instrument	O
used	O
to	O
characterize	O
an	O
optical	B-Architecture
fiber	I-Architecture
.	O
</s>
<s>
An	O
OTDR	B-Protocol
injects	O
a	O
series	O
of	O
optical	O
pulses	O
into	O
the	O
fiber	O
under	O
test	O
and	O
extracts	O
,	O
from	O
the	O
same	O
end	O
of	O
the	O
fiber	O
,	O
light	O
that	O
is	O
scattered	O
(	O
Rayleigh	O
backscatter	O
)	O
or	O
reflected	O
back	O
from	O
points	O
along	O
the	O
fiber	O
.	O
</s>
<s>
The	O
scattered	O
or	O
reflected	O
light	O
that	O
is	O
gathered	O
back	O
is	O
used	O
to	O
characterize	O
the	O
optical	B-Architecture
fiber	I-Architecture
.	O
</s>
<s>
The	O
reliability	O
and	O
quality	O
of	O
an	O
OTDR	B-Protocol
is	O
based	O
on	O
its	O
accuracy	O
,	O
measurement	O
range	O
,	O
ability	O
to	O
resolve	O
and	O
measure	O
closely	O
spaced	O
events	O
,	O
measurement	O
speed	O
,	O
and	O
ability	O
to	O
perform	O
satisfactorily	O
under	O
various	O
environmental	O
extremes	O
and	O
after	O
various	O
types	O
of	O
physical	O
abuse	O
.	O
</s>
<s>
Some	O
of	O
the	O
terms	O
often	O
used	O
in	O
specifying	O
the	O
quality	O
of	O
an	O
OTDR	B-Protocol
are	O
as	O
follows	O
:	O
</s>
<s>
The	O
duration	O
of	O
the	O
measurement	O
pulse	O
and	O
the	O
data	O
sampling	O
interval	O
create	O
a	O
resolution	O
limitation	O
for	O
OTDRs	B-Protocol
.	O
</s>
<s>
Resolution	O
is	O
also	O
often	O
limited	O
when	O
powerful	O
reflections	O
return	O
to	O
the	O
OTDR	B-Protocol
and	O
temporarily	O
overload	O
the	O
detector	O
.	O
</s>
<s>
Some	O
OTDR	B-Protocol
manufacturers	O
use	O
a	O
“	O
masking	O
”	O
procedure	O
to	O
improve	O
resolution	O
.	O
</s>
<s>
Industry	O
requirements	O
for	O
the	O
reliability	O
and	O
quality	O
of	O
OTDRs	B-Protocol
are	O
specified	O
in	O
the	O
Generic	O
Requirements	O
for	O
Optical	B-Protocol
Time	I-Protocol
Domain	I-Protocol
Reflectometer	I-Protocol
(	O
OTDR	B-Protocol
)	O
Type	O
Equipment	O
.	O
</s>
<s>
The	O
common	O
types	O
of	O
OTDR-like	O
test	O
equipment	O
are	O
:	O
</s>
<s>
Full-feature	O
OTDR	B-Protocol
:	O
</s>
<s>
Full-feature	O
OTDRs	B-Protocol
are	O
traditional	O
,	O
optical	B-Protocol
time	I-Protocol
domain	I-Protocol
reflectometers	I-Protocol
.	O
</s>
<s>
They	O
are	O
feature-rich	O
and	O
usually	O
larger	O
,	O
heavier	O
,	O
and	O
less	O
portable	O
than	O
either	O
the	O
hand-held	O
OTDR	B-Protocol
or	O
the	O
fiber	O
break	O
locator	O
.	O
</s>
<s>
Despite	O
being	O
characterized	O
as	O
large	O
,	O
their	O
size	O
and	O
weight	O
is	O
only	O
a	O
fraction	O
of	O
that	O
of	O
early	O
generation	O
OTDRs	B-Protocol
.	O
</s>
<s>
Often	O
a	O
full-feature	O
OTDR	B-Protocol
has	O
a	O
main	O
frame	O
that	O
can	O
be	O
fitted	O
with	O
multi-function	O
plug-in	O
units	O
to	O
perform	O
many	O
fiber	O
measurement	O
tasks	O
.	O
</s>
<s>
The	O
full-feature	O
OTDR	B-Protocol
often	O
has	O
a	O
greater	O
measurement	O
range	O
than	O
the	O
other	O
types	O
of	O
OTDR-like	O
equipment	O
.	O
</s>
<s>
Most	O
full-feature	O
OTDRs	B-Protocol
are	O
powered	O
from	O
AC	O
and/or	O
a	O
battery	O
.	O
</s>
<s>
Hand-held	O
OTDR	B-Protocol
and	O
Fiber	O
break	O
locator	O
:	O
</s>
<s>
Hand-held	O
(	O
formerly	O
mini	O
)	O
OTDRs	B-Protocol
and	O
fiber	O
break	O
locators	O
are	O
designed	O
to	O
troubleshoot	O
fiber	O
networks	O
in	O
a	O
field	O
environment	O
,	O
often	O
using	O
battery	O
power	O
.	O
</s>
<s>
The	O
two	O
types	O
of	O
instruments	O
cover	O
the	O
spectrum	O
of	O
approaches	O
to	O
fiber	B-Architecture
optic	I-Architecture
plant	O
taken	O
by	O
communication	O
providers	O
.	O
</s>
<s>
Hand-held	O
,	O
inexpensive	O
OTDRs	B-Protocol
are	O
intended	O
to	O
be	O
easy-to-use	O
,	O
light-weight	O
,	O
sophisticated	O
OTDRs	B-Protocol
that	O
collect	O
field	O
data	O
and	O
perform	O
rudimentary	O
data	O
analysis	O
.	O
</s>
<s>
They	O
may	O
be	O
less	O
feature	O
rich	O
than	O
full-feature	O
OTDRs	B-Protocol
.	O
</s>
<s>
Hand-held	O
OTDRs	B-Protocol
are	O
commonly	O
used	O
to	O
measure	O
fiber	O
links	O
and	O
locate	O
fiber	O
breaks	O
,	O
points	O
of	O
high	O
loss	O
,	O
high	O
reflectance	O
,	O
end-to-end	O
loss	O
,	O
and	O
Optical	O
Return	O
Loss	O
(	O
ORL	O
)	O
.	O
</s>
<s>
In	O
general	O
,	O
hand-held	O
OTDRs	B-Protocol
and	O
fiber	O
break	O
locators	O
are	O
lighter	O
and	O
smaller	O
,	O
simpler	O
to	O
operate	O
,	O
and	O
more	O
likely	O
to	O
employ	O
battery	O
power	O
than	O
full-feature	O
OTDRs	B-Protocol
.	O
</s>
<s>
The	O
intent	O
with	O
hand-held	O
OTDRs	B-Protocol
and	O
fiber	O
break	O
locators	O
is	O
to	O
be	O
inexpensive	O
enough	O
for	O
field	O
technicians	O
to	O
be	O
equipped	O
with	O
one	O
as	O
part	O
of	O
a	O
standard	O
tool	O
kit	O
.	O
</s>
<s>
A	O
central	O
computer	O
is	O
used	O
to	O
control	O
the	O
operation	O
of	O
OTDR-like	O
test	O
components	O
located	O
at	O
key	O
points	O
in	O
the	O
fiber	O
network	O
.	O
</s>
<s>
The	O
RFTS	O
can	O
also	O
provide	O
direct	O
access	O
to	O
a	O
database	O
that	O
contains	O
historical	O
information	O
of	O
the	O
OTDR	B-Protocol
fiber	O
traces	O
and	O
any	O
other	O
fiber	O
records	O
for	O
the	O
physical	O
fiber	O
plant	O
.	O
</s>
<s>
Since	O
OTDRs	B-Protocol
and	O
OTDR-like	O
equipment	O
have	O
many	O
uses	O
in	O
the	O
communications	O
industry	O
,	O
operating	O
environments	O
vary	O
widely	O
,	O
both	O
indoors	O
and	O
outdoors	O
.	O
</s>
<s>
In	O
the	O
late	O
1990s	O
,	O
OTDR	B-Protocol
industry	O
representatives	O
and	O
the	O
OTDR	B-Protocol
user	O
community	O
developed	O
a	O
unique	O
data	O
format	O
to	O
store	O
and	O
analyze	O
OTDR	B-Protocol
fiber	O
data	O
.	O
</s>
<s>
This	O
data	O
was	O
based	O
on	O
the	O
specifications	O
in	O
GR-196	O
,	O
Generic	O
Requirements	O
for	O
Optical	B-Protocol
Time	I-Protocol
Domain	I-Protocol
Reflectometer	I-Protocol
(	O
OTDR	B-Protocol
)	O
Type	O
Equipment	O
.	O
</s>
<s>
The	O
goal	O
was	O
for	O
the	O
data	O
format	O
to	O
be	O
truly	O
universal	O
,	O
in	O
that	O
it	O
was	O
intended	O
to	O
be	O
implemented	O
by	O
all	O
OTDR	B-Protocol
manufacturers	O
.	O
</s>
<s>
OTDR	B-Protocol
suppliers	O
developed	O
the	O
software	O
to	O
implement	O
the	O
data	O
format	O
.	O
</s>
<s>
From	O
1997	O
to	O
2000	O
,	O
a	O
group	O
of	O
OTDR	B-Protocol
supplier	O
software	O
specialists	O
attempted	O
to	O
resolve	O
problems	O
and	O
inconsistencies	O
in	O
what	O
was	O
then	O
called	O
the	O
“	O
Bellcore	O
”	O
OTDR	B-Protocol
Data	O
Format	O
.	O
</s>
<s>
This	O
group	O
,	O
called	O
the	O
OTDR	B-Protocol
Data	O
Format	O
Users	O
Group	O
(	O
ODFUG	O
)	O
,	O
made	O
progress	O
.	O
</s>
<s>
Since	O
then	O
,	O
many	O
OTDR	B-Protocol
developers	O
continued	O
to	O
work	O
with	O
other	O
developers	O
to	O
solve	O
individual	O
interaction	O
problems	O
and	O
enable	O
cross	O
use	O
between	O
manufacturers	O
.	O
</s>
<s>
In	O
2011	O
,	O
Telcordia	O
decided	O
to	O
compile	O
industry	O
comments	O
on	O
this	O
data	O
format	O
into	O
one	O
document	O
entitled	O
Optical	B-Protocol
Time	I-Protocol
Domain	I-Protocol
Reflectometer	I-Protocol
(	O
OTDR	B-Protocol
)	O
Data	O
Format	O
.	O
</s>
<s>
This	O
Special	O
Report	O
(	O
SR	O
)	O
summarizes	O
the	O
state	O
of	O
the	O
Bellcore	O
OTDR	B-Protocol
Data	O
Format	O
,	O
renaming	O
it	O
as	O
the	O
Telcordia	O
OTDR	B-Protocol
Data	O
Format	O
.	O
</s>
<s>
The	O
data	O
format	O
is	O
intended	O
for	O
all	O
OTDR-related	O
equipment	O
designed	O
to	O
save	O
trace	O
data	O
and	O
analysis	O
information	O
.	O
</s>
<s>
Initial	O
implementations	O
require	O
standalone	O
software	O
to	O
be	O
provided	O
by	O
the	O
OTDR	B-Protocol
supplier	O
to	O
convert	O
existing	O
OTDR	B-Protocol
trace	O
files	O
to	O
the	O
SR-4731	O
data	O
format	O
and	O
to	O
convert	O
files	O
from	O
this	O
universal	O
format	O
to	O
a	O
format	O
that	O
is	O
usable	O
by	O
their	O
older	O
OTDRs	B-Protocol
.	O
</s>
<s>
This	O
software	O
also	O
provides	O
backward	O
compatibility	O
of	O
the	O
OTDR	B-Protocol
data	O
format	O
with	O
existing	O
equipment	O
.	O
</s>
<s>
OTDR	B-Protocol
waveform	O
data	O
are	O
represented	O
as	O
short	O
,	O
unsigned	O
integer	O
data	O
uniformly	O
spaced	O
in	O
time	O
,	O
in	O
units	O
of	O
decibels	O
(	O
dB	O
)	O
times	O
1000	O
,	O
referenced	O
to	O
the	O
maximum	O
power	O
level	O
.	O
</s>
