<s>
A	O
marine	B-Algorithm
radar	I-Algorithm
with	O
automatic	B-Algorithm
radar	I-Algorithm
plotting	I-Algorithm
aid	I-Algorithm
(	O
ARPA	O
)	O
capability	O
can	O
create	O
tracks	O
using	O
radar	B-Application
contacts	O
.	O
</s>
<s>
ARPA	O
radars	B-Application
started	O
to	O
emerge	O
in	O
the	O
1960s	O
,	O
with	O
the	O
development	O
of	O
microelectronics	O
.	O
</s>
<s>
ARPA-enabled	O
radars	B-Application
are	O
now	O
available	O
even	O
for	O
small	O
yachts	O
.	O
</s>
<s>
The	O
availability	O
of	O
low	O
cost	O
microprocessors	B-Architecture
and	O
the	O
development	O
of	O
advanced	O
computer	O
technology	O
during	O
the	O
1970s	O
and	O
1980s	O
have	O
made	O
it	O
possible	O
to	O
apply	O
computer	O
techniques	O
to	O
improve	O
commercial	O
marine	B-Algorithm
radar	I-Algorithm
systems	O
.	O
</s>
<s>
Radar	B-Application
manufacturers	O
used	O
this	O
technology	O
to	O
create	O
the	O
Automatic	B-Algorithm
Radar	I-Algorithm
Plotting	I-Algorithm
Aids	I-Algorithm
.	O
</s>
<s>
The	O
International	O
Maritime	O
Organization	O
(	O
IMO	O
)	O
has	O
set	O
out	O
certain	O
standards	O
amending	O
the	O
International	O
Convention	O
for	O
the	O
Safety	O
of	O
Life	O
at	O
Sea	O
requirements	O
regarding	O
the	O
carrying	O
of	O
suitable	O
automated	O
radar	B-Application
plotting	O
aids	O
.	O
</s>
<s>
True	O
or	O
relative	O
motion	O
radar	B-Application
presentation	O
.	O
</s>
<s>
The	O
ability	O
to	O
display	O
collision	O
assessment	O
information	O
directly	O
on	O
the	O
Plan	B-Algorithm
Position	I-Algorithm
Indicator	I-Algorithm
(	O
PPI	O
)	O
,	O
using	O
vectors	O
(	O
true	O
or	O
relative	O
)	O
or	O
a	O
graphical	O
Predicted	O
Area	O
of	O
Danger	O
(	O
PAD	O
)	O
display	O
.	O
</s>
<s>
ARPA	O
processes	O
radar	B-Application
information	O
much	O
more	O
rapidly	O
than	O
conventional	O
radar	B-Application
but	O
is	O
still	O
subject	O
to	O
the	O
same	O
limitations	O
.	O
</s>
<s>
That	O
is	O
because	O
they	O
were	O
designed	O
to	O
be	O
an	O
addition	O
to	O
the	O
conventional	O
radar	B-Application
unit	O
.	O
</s>
<s>
All	O
of	O
the	O
ARPA	O
functions	O
were	O
installed	O
on	O
board	O
as	O
a	O
separate	O
unit	O
,	O
but	O
needed	O
to	O
be	O
interfaced	O
with	O
existing	O
equipment	O
to	O
get	O
the	O
basic	O
radar	B-Application
data	O
.	O
</s>
<s>
The	O
primary	O
benefits	O
were	O
cost	O
and	O
time	O
savings	O
for	O
ships	O
already	O
equipped	O
with	O
radar	B-Application
.	O
</s>
<s>
The	O
majority	O
of	O
ARPAs	O
manufactured	O
in	O
the	O
21st	O
century	O
integrate	O
the	O
ARPA	O
features	O
with	O
the	O
radar	B-Application
display	O
.	O
</s>
<s>
The	O
modern	O
integral	O
ARPA	O
combines	O
the	O
conventional	O
radar	B-Application
data	O
with	O
the	O
computer	O
data	O
processing	O
systems	O
into	O
one	O
unit	O
.	O
</s>
<s>
The	O
main	O
operational	O
advantage	O
is	O
that	O
both	O
the	O
radar	B-Application
and	O
ARPA	O
data	O
are	O
readily	O
comparable	O
.	O
</s>
<s>
From	O
the	O
time	O
radar	B-Application
was	O
first	O
introduced	O
to	O
the	O
present	O
day	O
the	O
radar	B-Application
picture	O
has	O
been	O
presented	O
on	O
the	O
screen	O
of	O
a	O
cathode	B-Device
ray	I-Device
tube	I-Device
.	O
</s>
<s>
Although	O
the	O
cathode	B-Device
ray	I-Device
tube	I-Device
has	O
retained	O
its	O
function	O
over	O
the	O
years	O
,	O
the	O
way	O
in	O
which	O
the	O
picture	O
is	O
presented	O
has	O
changed	O
considerably	O
.	O
</s>
<s>
The	O
radial-scan	O
Plan	B-Algorithm
position	I-Algorithm
indicator	I-Algorithm
(	O
PPI	O
)	O
was	O
replaced	O
by	O
a	O
raster-scan	O
PPI	O
generated	O
on	O
a	O
television	O
type	O
of	O
display	O
.	O
</s>
<s>
the	O
radial-scan	O
radar	B-Application
sets	O
.	O
</s>
<s>
The	O
development	O
of	O
commercial	O
marine	B-Algorithm
radar	I-Algorithm
entered	O
a	O
new	O
phase	O
in	O
the	O
1980s	O
when	O
raster-scan	O
displays	O
that	O
were	O
compliant	O
with	O
the	O
IMO	O
Performance	O
Standards	O
were	O
introduced	O
.	O
</s>
<s>
The	O
radar	B-Application
picture	O
of	O
a	O
raster-scan	O
synthetic	O
display	O
is	O
produced	O
on	O
a	O
television	O
screen	O
and	O
is	O
made	O
up	O
of	O
a	O
large	O
number	O
of	O
horizontal	O
lines	O
which	O
form	O
a	O
pattern	O
known	O
as	O
a	O
raster	O
.	O
</s>
<s>
Out	O
of	O
all	O
the	O
benefits	O
offered	O
by	O
a	O
raster-scan	O
radar	B-Application
it	O
is	O
this	O
ability	O
which	O
has	O
assured	O
its	O
success	O
.	O
</s>
<s>
The	O
raster-scan	O
television	O
tubes	O
have	O
a	O
much	O
longer	O
life	O
than	O
a	O
traditional	O
radar	B-Application
cathode	B-Device
ray	I-Device
tube	I-Device
(	O
CRT	O
)	O
.	O
</s>
<s>
The	O
IMO	O
Performance	O
Standards	O
for	O
radar	B-Application
to	O
provide	O
a	O
plan	O
display	O
with	O
an	O
effective	O
display	O
diameter	O
of	O
180mm	O
,	O
250mm	O
,	O
or	O
340mm	O
depending	O
upon	O
the	O
gross	O
tonnage	O
of	O
the	O
vessel	O
.	O
</s>
