<s>
The	O
AMES	B-Algorithm
Type	I-Algorithm
82	I-Algorithm
,	O
also	O
widely	O
known	O
by	O
its	O
rainbow	O
codename	O
Orange	B-Algorithm
Yeoman	I-Algorithm
,	O
was	O
an	O
S-band	B-Algorithm
3D	B-Algorithm
radar	I-Algorithm
built	O
by	O
Marconi	B-Device
and	O
used	O
by	O
the	O
Royal	O
Air	O
Force	O
(	O
RAF	O
)	O
,	O
initially	O
for	O
tactical	O
control	O
and	O
later	O
for	O
air	B-Application
traffic	I-Application
control	I-Application
(	O
ATC	O
)	O
.	O
</s>
<s>
Development	O
started	O
in	O
1949	O
at	O
the	O
British	O
Army	O
's	O
Radar	O
Research	O
and	O
Development	O
Establishment	O
to	O
provide	O
medium-range	O
early	B-Algorithm
warning	I-Algorithm
for	O
up	O
to	O
sixteen	O
anti-aircraft	O
artillery	O
(	O
AAA	O
)	O
batteries	O
.	O
</s>
<s>
This	O
provided	O
a	O
semi-automated	O
track	B-Algorithm
while	I-Algorithm
scan	I-Algorithm
function	O
that	O
allowed	O
operators	O
to	O
handle	O
larger	O
numbers	O
of	O
aircraft	O
.	O
</s>
<s>
They	O
were	O
then	O
repurposed	O
as	O
air	B-Application
traffic	I-Application
control	I-Application
systems	I-Application
,	O
where	O
its	O
ability	O
to	O
measure	O
range	O
,	O
bearing	O
,	O
elevation	O
and	O
secondary	O
radar	O
information	O
in	O
a	O
single	O
unit	O
was	O
a	O
major	O
advantage	O
over	O
previous	O
systems	O
.	O
</s>
<s>
By	O
the	O
late-war	O
period	O
,	O
the	O
same	O
developers	O
had	O
produced	O
a	O
model	O
using	O
a	O
cavity	B-Architecture
magnetron	I-Architecture
known	O
as	O
the	O
Microwave	O
Zone	O
Position	O
Indicator	O
(	O
MZPI	O
)	O
.	O
</s>
<s>
This	O
could	O
be	O
accomplished	O
by	O
a	O
separate	O
height	B-Algorithm
finding	I-Algorithm
radar	I-Algorithm
,	O
but	O
a	O
single	O
radar	O
that	O
could	O
provide	O
reasonably	O
accurate	O
direction	O
and	O
altitude	O
would	O
make	O
this	O
process	O
easier	O
.	O
</s>
<s>
The	O
Radar	O
Research	O
and	O
Development	O
Establishment	O
(	O
RRDE	O
)	O
,	O
who	O
handled	O
the	O
development	O
of	O
radars	O
for	O
the	O
Army	O
,	O
began	O
exploring	O
the	O
idea	O
of	O
a	O
3D	B-Algorithm
radar	I-Algorithm
that	O
could	O
measure	O
the	O
vertical	O
angle	O
of	O
the	O
target	O
at	O
the	O
same	O
time	O
as	O
its	O
bearing	O
and	O
range	O
.	O
</s>
<s>
Serious	O
work	O
on	O
the	O
concept	O
began	O
in	O
1947	O
,	O
first	O
with	O
a	O
mechanically	O
spiral-scanned	O
X-band	B-Algorithm
system	O
,	O
and	O
later	O
,	O
various	O
experiments	O
with	O
stacked	O
feeds	O
.	O
</s>
<s>
At	O
the	O
same	O
time	O
,	O
research	O
began	O
on	O
the	O
design	O
of	O
a	O
new	O
high-power	O
25cm	O
wavelength	O
(	O
L-band	B-Algorithm
)	O
cavity	B-Architecture
magnetron	I-Architecture
,	O
a	O
new	O
large-format	O
long-persistence	O
plan-position	B-Algorithm
indicator	I-Algorithm
display	O
tube	O
,	O
and	O
a	O
data	O
link	O
system	O
to	O
send	O
the	O
information	O
to	O
as	O
many	O
as	O
sixteen	O
remote	O
sites	O
.	O
</s>
<s>
By	O
mid-1948	O
the	O
basic	O
design	O
was	O
complete	O
;	O
it	O
would	O
operate	O
in	O
the	O
X-band	B-Algorithm
at	O
10cm	O
wavelength	O
and	O
use	O
ten	O
feedhorns	O
,	O
each	O
one	O
with	O
a	O
3degree	O
vertical	O
beam	O
.	O
</s>
<s>
In	O
1949	O
the	O
Ministry	O
of	O
Supply	O
took	O
over	O
direct	O
control	O
of	O
the	O
TRE	O
and	O
RRDE	O
,	O
and	O
assigned	O
the	O
3D	O
work	O
the	O
Rainbow	O
Code	O
"	O
Orange	B-Algorithm
Yeoman	I-Algorithm
"	O
.	O
</s>
<s>
To	O
produce	O
more	O
power	O
in	O
total	O
,	O
a	O
system	O
was	O
developed	O
to	O
feed	O
three	O
magnetrons	B-Device
in	O
parallel	O
.	O
</s>
<s>
The	O
Royal	O
Navy	O
had	O
been	O
developing	O
its	O
own	O
3D	B-Algorithm
radar	I-Algorithm
in	O
this	O
period	O
,	O
the	O
Type	O
984	O
radar	O
,	O
and	O
in	O
May	O
1950	O
there	O
was	O
some	O
consideration	O
of	O
whether	O
or	O
not	O
it	O
should	O
be	O
used	O
in	O
the	O
RAF	O
as	O
well	O
.	O
</s>
<s>
In	O
June	O
1950	O
,	O
the	O
Defence	O
Research	O
Policy	O
Committee	O
studied	O
whether	O
the	O
984	O
or	O
Orange	B-Algorithm
Yeoman	I-Algorithm
might	O
better	O
fill	O
the	O
requirement	O
.	O
</s>
<s>
There	O
was	O
increasing	O
interest	O
in	O
Orange	B-Algorithm
Yeoman	I-Algorithm
as	O
a	O
system	O
to	O
help	O
direct	O
these	O
weapons	O
,	O
which	O
were	O
expected	O
to	O
be	O
available	O
in	O
the	O
mid-to-late	O
1950s	O
.	O
</s>
<s>
AAA	O
would	O
remain	O
in	O
use	O
through	O
a	O
transition	O
period	O
,	O
and	O
there	O
was	O
a	O
desire	O
to	O
accurately	O
feed	O
the	O
information	O
from	O
Orange	B-Algorithm
Yeoman	I-Algorithm
to	O
their	O
existing	O
Mark	O
VII	O
radars	O
.	O
</s>
<s>
This	O
led	O
to	O
a	O
requirement	O
for	O
Orange	B-Algorithm
Yeoman	I-Algorithm
to	O
have	O
an	O
80%	O
probability	O
of	O
producing	O
a	O
track	O
that	O
was	O
accurate	O
to	O
within	O
in	O
position	O
and	O
altitude	O
.	O
</s>
<s>
A	O
major	O
one	O
was	O
that	O
the	O
planned	O
S-band	B-Algorithm
magnetron	B-Device
,	O
the	O
BM	O
735	O
,	O
was	O
only	O
available	O
in	O
small	O
numbers	O
and	O
would	O
rarely	O
work	O
when	O
pushed	O
beyond	O
1MW	O
of	O
its	O
2MW	O
rated	O
power	O
.	O
</s>
<s>
This	O
led	O
to	O
experiments	O
with	O
slip-rings	O
that	O
fed	O
the	O
intermediate	O
frequency	O
(	O
IF	O
)	O
instead	O
,	O
with	O
the	O
magnetron	B-Device
transmitters	O
and	O
first	O
stages	O
of	O
the	O
superheterodyne	O
receivers	O
on	O
the	O
rotating	O
platform	O
.	O
</s>
<s>
This	O
led	O
to	O
a	O
system	O
using	O
a	O
single	O
2MW	O
magnetron	B-Device
instead	O
of	O
three	O
ganged	O
ones	O
,	O
feeding	O
them	O
via	O
IF	O
slip-rings	O
,	O
and	O
using	O
separate	O
transmit	O
and	O
receive	O
antennas	O
.	O
</s>
<s>
This	O
would	O
provide	O
track	B-Algorithm
while	I-Algorithm
scan	I-Algorithm
capability	O
that	O
would	O
greatly	O
ease	O
the	O
task	O
of	O
deciding	O
which	O
AA	O
guns	O
should	O
be	O
trained	O
on	O
which	O
targets	O
.	O
</s>
<s>
A	O
larger	O
system	O
with	O
36	O
tracks	O
was	O
built	O
and	O
connected	O
to	O
the	O
prototype	O
Orange	B-Algorithm
Yeoman	I-Algorithm
during	O
1952	O
.	O
</s>
<s>
At	O
first	O
,	O
the	O
system	O
required	O
the	O
operators	O
to	O
update	O
the	O
information	O
for	O
a	O
given	O
track	O
by	O
watching	O
the	O
radar	O
display	O
and	O
moving	O
a	O
cursor	O
dot	O
with	O
a	O
joystick	B-Device
.	O
</s>
<s>
This	O
"	O
Analysis	O
Group	O
"	O
also	O
handled	O
the	O
identification	B-Device
friend	I-Device
or	I-Device
foe	I-Device
(	O
IFF	O
)	O
system	O
.	O
</s>
<s>
Three	O
locations	O
,	O
London	O
,	O
Liverpool	B-Application
and	O
Southampton	O
,	O
were	O
selected	O
for	O
operational	O
units	O
,	O
with	O
their	O
primary	O
role	O
being	O
to	O
hand	O
off	O
data	O
to	O
the	O
Yellow	O
River	O
radars	O
,	O
now	O
known	O
as	O
Radar	O
,	O
Anti-Aircraft	O
,	O
Number	O
3	O
,	O
Mark	O
V	O
or	O
AA	O
No.3	O
Mk.V.	O
</s>
<s>
In	O
June	O
1953	O
,	O
the	O
first	O
of	O
these	O
sites	O
was	O
selected	O
,	O
on	O
the	O
hills	O
near	O
Newton	O
overlooking	O
the	O
Frodsham	O
Anti-Aircraft	O
Operations	O
Room	O
covering	O
the	O
Liverpool	B-Application
area	O
and	O
relatively	O
close	O
to	O
the	O
Metrovick	O
works	O
.	O
</s>
<s>
As	O
part	O
of	O
this	O
handover	O
,	O
Orange	B-Algorithm
Yeoman	I-Algorithm
became	O
a	O
TRE	O
project	O
and	O
was	O
assigned	O
the	O
name	O
AMES	B-Algorithm
Type	I-Algorithm
82	I-Algorithm
,	O
although	O
the	O
actual	O
development	O
remained	O
at	O
the	O
normally	O
Army-related	O
RRDE	O
.	O
</s>
<s>
The	O
RAF	O
initially	O
saw	O
a	O
role	O
for	O
the	O
Orange	B-Algorithm
Yeoman	I-Algorithm
similar	O
to	O
that	O
of	O
the	O
Army	O
,	O
and	O
continued	O
development	O
of	O
two	O
prototypes	O
and	O
three	O
production	O
sites	O
.	O
</s>
<s>
In	O
1955	O
,	O
a	O
series	O
of	O
tests	O
using	O
the	O
Orange	B-Algorithm
Yeoman	I-Algorithm
and	O
Data	O
Handling	O
System	O
at	O
Malvern	O
and	O
a	O
Yellow	O
River	O
radar	O
located	O
away	O
to	O
the	O
north	O
succeeded	O
in	O
automatically	O
directing	O
the	O
Yellow	O
River	O
onto	O
a	O
target	O
aircraft	O
with	O
a	O
100%	O
success	O
rate	O
with	O
no	O
intervention	O
by	O
the	O
operators	O
of	O
the	O
Yellow	O
River	O
.	O
</s>
<s>
In	O
1950	O
a	O
new	O
type	O
of	O
microwave-frequency	O
vacuum	O
tube	O
known	O
as	O
the	O
carcinotron	B-Algorithm
was	O
introduced	O
by	O
the	O
French	O
company	O
CSF	O
.	O
</s>
<s>
The	O
carcinotron	B-Algorithm
was	O
unique	O
in	O
that	O
its	O
output	O
frequency	O
could	O
be	O
changed	O
across	O
a	O
wide	O
band	O
by	O
changing	O
the	O
input	O
voltage	O
.	O
</s>
<s>
In	O
tests	O
it	O
was	O
found	O
to	O
produce	O
a	O
solid	O
signal	O
on	O
the	O
Type	O
80	O
display	O
even	O
when	O
it	O
was	O
under	O
the	O
radar	B-Algorithm
horizon	I-Algorithm
.	O
</s>
<s>
These	O
tests	O
appeared	O
to	O
suggest	O
that	O
the	O
carcinotron	B-Algorithm
would	O
make	O
long-distance	O
radars	O
useless	O
,	O
and	O
interest	O
in	O
using	O
Orange	B-Algorithm
Yeoman	I-Algorithm
as	O
a	O
tactical	O
radar	O
during	O
wartime	O
disappeared	O
.	O
</s>
<s>
There	O
was	O
also	O
an	O
effort	O
to	O
interest	O
the	O
civilian	O
air	B-Application
traffic	I-Application
control	I-Application
authorities	O
in	O
the	O
system	O
,	O
especially	O
for	O
the	O
experimental	O
Northern	O
Air	B-Application
Traffic	I-Application
Control	I-Application
Center	O
being	O
set	O
up	O
in	O
Preston	O
,	O
Lancashire	O
outside	O
Liverpool	B-Application
.	O
</s>
<s>
By	O
this	O
time	O
the	O
Type	O
80s	O
were	O
covering	O
the	O
same	O
area	O
,	O
and	O
there	O
was	O
concern	O
that	O
the	O
carcinotron	B-Algorithm
would	O
render	O
the	O
Type	O
82	O
useless	O
in	O
a	O
war	O
anyway	O
.	O
</s>
<s>
Servicing	O
of	O
the	O
systems	O
passed	O
to	O
civilian	O
contractors	O
,	O
and	O
they	O
were	O
manned	O
by	O
both	O
military	O
and	O
civilian	O
air	B-Application
traffic	I-Application
controllers	O
.	O
</s>
<s>
The	O
transmitter	O
consisted	O
of	O
a	O
slotted	B-Algorithm
waveguide	I-Algorithm
in	O
front	O
of	O
a	O
cosecant-squared	B-Algorithm
linear	I-Algorithm
reflector	I-Algorithm
wide	O
by	O
high	O
.	O
</s>
<s>
The	O
IFF	O
antenna	O
was	O
also	O
a	O
slotted	B-Algorithm
waveguide	I-Algorithm
,	O
positioned	O
above	O
the	O
receiver	O
array	O
.	O
</s>
<s>
The	O
transmitter	O
was	O
a	O
magnetron	B-Device
that	O
produced	O
pulses	O
of	O
1.5MW	O
at	O
3GHz	O
with	O
a	O
pulse	O
repetition	O
frequency	O
(	O
PRF	O
)	O
of	O
750	O
pulses	O
per	O
second	O
and	O
a	O
pulse	O
length	O
of	O
2microseconds	O
.	O
</s>
<s>
Initial	O
data	O
for	O
a	O
track	O
was	O
entered	O
by	O
two	O
dedicated	O
Track	O
Allocators	O
who	O
considered	O
only	O
the	O
outermost	O
regions	O
of	O
the	O
plan-position	B-Algorithm
indicators	I-Algorithm
.	O
</s>
<s>
They	O
would	O
then	O
begin	O
tracking	O
the	O
target	O
by	O
moving	O
the	O
joystick	B-Device
so	O
their	O
on-screen	O
cursor	O
remained	O
on	O
top	O
of	O
the	O
blip	O
as	O
it	O
moved	O
from	O
sweep	O
to	O
sweep	O
.	O
</s>
