<s>
Martello	O
is	O
a	O
family	O
of	O
phased	B-Algorithm
array	I-Algorithm
radar	I-Algorithm
systems	O
developed	O
by	O
Marconi	B-Device
Electronic	O
Systems	O
in	O
the	O
1970s	O
and	O
introduced	O
operationally	O
in	O
the	O
early	O
1980s	O
.	O
</s>
<s>
They	O
provided	O
long-range	O
early	B-Algorithm
warning	I-Algorithm
capabilities	O
but	O
also	O
had	O
the	O
accuracy	O
needed	O
for	O
interception	O
plotting	O
and	O
"	O
putting	O
on	O
"	O
of	O
other	O
weapons	O
systems	O
like	O
surface-to-air	O
missiles	O
.	O
</s>
<s>
Earlier	O
mechanically	O
scanned	O
3D	B-Algorithm
radars	I-Algorithm
used	O
multiple	O
feed	O
horns	O
in	O
a	O
vertical	O
stack	O
,	O
but	O
this	O
was	O
difficult	O
to	O
make	O
in	O
a	O
mobile	O
form	O
;	O
when	O
moved	O
they	O
would	O
go	O
out	O
of	O
alignment	O
.	O
</s>
<s>
The	O
first	O
S713	O
was	O
introduced	O
in	O
1978	O
and	O
entered	O
RAF	O
service	O
in	O
1982	O
as	O
the	O
AMES	B-Algorithm
Type	I-Algorithm
90	I-Algorithm
.	O
</s>
<s>
Changes	O
to	O
the	O
NATO	O
specification	O
led	O
to	O
the	O
S723	O
,	O
introduced	O
in	O
1984	O
and	O
entering	O
service	O
with	O
the	O
RAF	O
in	O
1986	O
as	O
the	O
AMES	B-Algorithm
Type	I-Algorithm
91	I-Algorithm
.	O
</s>
<s>
The	O
Lockheed	B-Application
Martin	I-Application
AN/TPS	I-Application
-77	I-Application
has	O
replaced	O
the	O
Martellos	O
in	O
the	O
UK	O
,	O
as	O
the	O
AMES	B-Application
Type	I-Application
92	I-Application
.	O
</s>
<s>
Marconi	B-Device
was	O
the	O
leading	O
supplier	O
of	O
ground-based	O
radars	O
in	O
the	O
UK	O
for	O
many	O
years	O
,	O
mostly	O
working	O
with	O
designs	O
developed	O
at	O
the	O
Royal	O
Radar	O
Establishment	O
(	O
RRE	O
)	O
and	O
its	O
predecessors	O
.	O
</s>
<s>
These	O
generally	O
used	O
large	O
radars	O
for	O
2D	O
scanning	O
to	O
a	O
plan-position	B-Algorithm
indicator	I-Algorithm
(	O
PPI	O
)	O
display	O
and	O
separate	O
height	B-Algorithm
finding	I-Algorithm
radars	I-Algorithm
for	O
measuring	O
target	O
altitudes	O
.	O
</s>
<s>
A	O
new	O
product	O
concept	O
emerged	O
from	O
this	O
process	O
,	O
a	O
long-range	O
air-scanning	O
radar	O
to	O
provide	O
battlefield	O
overview	O
and	O
early	B-Algorithm
warning	I-Algorithm
,	O
what	O
the	O
British	O
Army	O
called	O
a	O
tactical	O
control	O
radar	O
.	O
</s>
<s>
The	O
design	O
also	O
intended	O
to	O
use	O
the	O
same	O
components	O
to	O
serve	O
different	O
roles	O
,	O
including	O
air	B-Application
traffic	I-Application
control	I-Application
and	O
fixed-place	O
systems	O
.	O
</s>
<s>
It	O
combined	O
a	O
traditional	O
rotating	O
radar	O
scanner	O
for	O
detection	O
and	O
measurement	O
of	O
bearing	O
with	O
one	O
or	O
more	O
height	B-Algorithm
finder	I-Algorithm
radars	I-Algorithm
to	O
measure	O
altitude	O
.	O
</s>
<s>
A	O
unique	O
feature	O
was	O
that	O
the	O
main	O
scanner	O
optionally	O
mounted	O
two	O
antennas	O
back-to-back	O
and	O
could	O
be	O
operated	O
in	O
the	B-Algorithm
S	I-Algorithm
band	I-Algorithm
and	O
L	B-Algorithm
band	I-Algorithm
at	O
the	O
same	O
time	O
.	O
</s>
<s>
This	O
concept	O
emerged	O
as	O
the	O
Marconi	B-Device
S600	O
,	O
which	O
was	O
first	O
announced	O
in	O
May	O
1967	O
and	O
demonstrated	O
at	O
the	O
1968	O
Farnborough	O
Air	O
Show	O
.	O
</s>
<s>
This	O
process	O
produced	O
several	O
new	O
requirements	O
;	O
like	O
the	O
S600	O
,	O
the	O
system	O
should	O
be	O
mobile	O
or	O
at	O
least	O
transportable	O
,	O
that	O
it	O
have	O
improved	O
jamming	O
resistance	O
,	O
and	O
that	O
the	O
era	O
of	O
the	O
2D	O
radar	O
and	O
separate	O
height	B-Algorithm
finder	I-Algorithm
used	O
in	O
the	O
S600	O
was	O
over	O
and	O
that	O
the	O
new	O
design	O
had	O
to	O
have	O
a	O
single	O
3D	O
antenna	O
.	O
</s>
<s>
Marconi	B-Device
had	O
worked	O
on	O
3D	O
systems	O
in	O
the	O
past	O
,	O
notably	O
the	O
Orange	B-Algorithm
Yeoman	I-Algorithm
radar	O
of	O
the	O
early	O
1960s	O
.	O
</s>
<s>
One	O
possible	O
solution	O
was	O
found	O
by	O
accident	O
;	O
the	O
AMES	O
Type	O
14	O
and	O
AMES	O
Type	O
80	O
radars	O
used	O
an	O
end-fed	O
slotted	B-Algorithm
waveguide	I-Algorithm
to	O
feed	O
the	O
radar	O
signal	O
to	O
the	O
antenna	O
.	O
</s>
<s>
When	O
the	O
magnetron	B-Device
was	O
replaced	O
during	O
maintenance	O
,	O
the	O
new	O
one	O
would	O
have	O
a	O
slightly	O
different	O
frequency	O
and	O
this	O
would	O
cause	O
the	O
signal	O
to	O
shift	O
several	O
degrees	O
.	O
</s>
<s>
An	O
array	B-Algorithm
antenna	I-Algorithm
received	O
the	O
returned	O
echos	O
and	O
each	O
antenna	O
in	O
the	O
array	O
was	O
equipped	O
with	O
the	O
first	O
stage	O
of	O
a	O
superheterodyne	O
receiver	O
,	O
converting	O
the	O
original	O
microwave	O
frequency	O
signal	O
to	O
a	O
much	O
lower	O
intermediate	O
frequency	O
(	O
IF	O
)	O
.	O
</s>
<s>
In	O
1970	O
the	O
RRE	O
gave	O
Marconi	B-Device
a	O
contract	O
to	O
develop	O
a	O
prototype	O
of	O
a	O
commercial	O
version	O
of	O
STAR	O
.	O
</s>
<s>
Horizontal	O
scanning	O
would	O
be	O
achieved	O
as	O
it	O
had	O
in	O
the	O
past	O
,	O
by	O
rotating	O
the	O
entire	O
antenna	B-Algorithm
array	I-Algorithm
.	O
</s>
<s>
Such	O
a	O
system	O
can	O
steer	O
the	O
beam	O
vertically	O
by	O
delaying	O
the	O
signal	O
as	O
it	O
is	O
sent	O
to	O
the	O
elements	O
,	O
and	O
this	O
phased	B-Algorithm
array	I-Algorithm
radar	I-Algorithm
concept	O
was	O
being	O
actively	O
researched	O
,	O
especially	O
in	O
the	O
United	O
States	O
.	O
</s>
<s>
However	O
,	O
this	O
required	O
each	O
element	O
to	O
have	O
its	O
own	O
transmitter	O
as	O
well	O
as	O
receiver	O
,	O
and	O
in	O
the	O
era	O
of	O
electronics	O
made	O
of	O
individual	O
transistors	B-Application
,	O
these	O
were	O
very	O
expensive	O
.	O
</s>
<s>
In	O
contrast	O
,	O
Marconi	B-Device
's	O
concept	O
sent	O
out	O
a	O
single	O
fan-shaped	O
beam	O
as	O
in	O
STAR	O
,	O
and	O
required	O
only	O
the	O
receivers	O
to	O
be	O
individual	O
to	O
each	O
element	O
.	O
</s>
<s>
After	O
conversion	O
to	O
the	O
IF	O
,	O
the	O
signal	O
from	O
each	O
element	O
was	O
sent	O
into	O
a	O
series	O
of	O
fixed	O
delays	O
,	O
the	O
"	O
beam-forming	B-Algorithm
network	I-Algorithm
"	O
.	O
</s>
<s>
The	O
aimed	O
outputs	O
were	O
identical	O
to	O
those	O
created	O
by	O
the	O
separate	O
physical	O
feed	O
horns	O
in	O
a	O
system	O
like	O
Orange	B-Algorithm
Yeoman	I-Algorithm
,	O
but	O
implemented	O
completely	O
in	O
electronics	O
in	O
a	O
box	O
about	O
the	O
size	O
of	O
a	O
minibar	O
.	O
</s>
<s>
Altitude	O
information	O
was	O
extracted	O
as	O
it	O
had	O
been	O
in	O
Orange	B-Algorithm
Yeoman	I-Algorithm
;	O
comparing	O
a	O
received	O
pulse	O
's	O
strength	O
in	O
adjacent	O
outputs	O
allowed	O
the	O
vertical	O
angle	O
to	O
be	O
measured	O
with	O
some	O
degree	O
of	O
accuracy	O
.	O
</s>
<s>
Even	O
more	O
worrying	O
was	O
that	O
the	O
data	O
was	O
communicated	O
over	O
microwave	B-Application
relay	I-Application
,	O
which	O
opened	O
it	O
to	O
the	O
possibility	O
of	O
being	O
jammed	O
,	O
rendering	O
the	O
entire	O
network	O
useless	O
.	O
</s>
<s>
By	O
digitizing	O
this	O
data	O
early	O
in	O
the	O
process	O
,	O
it	O
could	O
be	O
passed	O
from	O
site	O
to	O
site	O
using	O
modems	B-Application
on	O
conventional	O
telephones	O
lines	O
,	O
which	O
would	O
provide	O
much	O
higher	O
security	O
and	O
some	O
level	O
of	O
redundancy	O
.	O
</s>
<s>
Marconi	B-Device
joined	O
a	O
consortium	O
with	O
Hughes	O
Aircraft	O
and	O
Plessey	O
which	O
won	O
the	O
contract	O
to	O
supply	O
the	O
networking	O
systems	O
,	O
with	O
Marconi	B-Device
supplying	O
over	O
200	O
of	O
the	O
standardized	O
operator	O
terminals	O
based	O
on	O
their	O
Locus	O
16	O
computers	O
.	O
</s>
<s>
Marconi	B-Device
saw	O
the	O
introduction	O
of	O
the	O
UKADGE	O
system	O
as	O
an	O
opportunity	O
to	O
make	O
practical	O
use	O
of	O
their	O
stacked-beam	O
design	O
.	O
</s>
<s>
Chain	O
Home	O
had	O
only	O
survived	O
attacks	O
by	O
the	O
Luftwaffe	O
due	O
to	O
the	O
availability	O
of	O
backup	O
radar	O
systems	O
that	O
could	O
be	O
put	O
into	O
operation	O
within	O
hours	O
,	O
and	O
Marconi	B-Device
noted	O
their	O
design	O
could	O
offer	O
the	O
same	O
capability	O
.	O
</s>
<s>
One	O
part	O
of	O
the	O
standard	O
specified	O
the	O
use	O
of	O
the	B-Algorithm
S	I-Algorithm
band	I-Algorithm
for	O
the	O
radars	O
.	O
</s>
<s>
Marconi	B-Device
suggested	O
using	O
the	O
L	B-Algorithm
band	I-Algorithm
instead	O
,	O
which	O
would	O
require	O
much	O
less	O
power	O
to	O
reach	O
the	O
same	O
range	O
.	O
</s>
<s>
The	O
UK	O
Ministry	O
of	O
Defence	O
took	O
up	O
their	O
cause	O
within	O
NATO	O
,	O
and	O
in	O
1974	O
the	O
requirement	O
for	O
S	B-Algorithm
band	I-Algorithm
was	O
dropped	O
.	O
</s>
<s>
At	O
this	O
point	O
,	O
Marconi	B-Device
had	O
what	O
appeared	O
to	O
be	O
a	O
sure	O
contract	O
win	O
with	O
the	O
RAF	O
but	O
that	O
would	O
be	O
a	O
small	O
number	O
of	O
radars	O
;	O
Linesman	O
had	O
only	O
three	O
main	O
sites	O
and	O
two	O
secondaries	O
.	O
</s>
<s>
Marconi	B-Device
won	O
the	O
contract	O
for	O
the	O
D	O
band	O
with	O
S713	O
,	O
whilst	O
Plessey	O
won	O
the	O
contract	O
for	O
the	O
E/F	O
band	O
systems	O
with	O
a	O
modified	O
version	O
of	O
their	O
civilian	O
frequency-scanned	O
systems	O
.	O
</s>
<s>
Feeling	O
they	O
still	O
had	O
a	O
high	O
chance	O
of	O
winning	O
contracts	O
for	O
NADGE	O
,	O
Marconi	B-Device
took	O
it	O
upon	O
themselves	O
to	O
develop	O
a	O
new	O
version	O
of	O
the	O
same	O
basic	O
system	O
to	O
meet	O
the	O
new	O
requirements	O
,	O
the	O
S723	O
.	O
</s>
<s>
During	O
this	O
period	O
,	O
semiconductor	O
technology	O
had	O
been	O
improving	O
dramatically	O
,	O
especially	O
in	O
the	O
high-power	O
market	O
where	O
transistors	B-Application
were	O
now	O
available	O
that	O
were	O
capable	O
of	O
controlling	O
tens	O
of	O
kilowatts	O
of	O
power	O
.	O
</s>
<s>
Marconi	B-Device
decided	O
to	O
modify	O
the	O
original	O
design	O
by	O
replacing	O
the	O
single	O
twystron	O
with	O
a	O
series	O
of	O
individual	O
transistorized	O
transmitter	O
modules	O
,	O
one	O
on	O
each	O
horizontal	O
row	O
.	O
</s>
<s>
This	O
would	O
normally	O
result	O
in	O
less	O
range	O
resolution	O
,	O
but	O
this	O
was	O
addressed	O
with	O
pulse	B-Algorithm
compression	I-Algorithm
in	O
the	O
receiver	O
,	O
compressing	O
the	O
150µs	O
pulse	O
to	O
0.25µs	O
,	O
the	O
same	O
length	O
as	O
the	O
compressed	O
pulse	O
in	O
the	O
S713	O
.	O
</s>
<s>
Fewer	O
arms	O
were	O
needed	O
as	O
the	O
vertical	O
coverage	O
was	O
not	O
as	O
great	O
,	O
and	O
the	O
number	O
of	O
outputs	O
from	O
the	O
beam-forming	B-Algorithm
network	I-Algorithm
could	O
be	O
reduced	O
to	O
as	O
few	O
as	O
six	O
.	O
</s>
<s>
By	O
1989	O
the	O
RAF	O
had	O
accepted	O
the	O
S713	O
in	O
service	O
as	O
the	O
AMES	B-Algorithm
Type	I-Algorithm
90	I-Algorithm
,	O
and	O
the	O
S723s	O
as	O
the	O
AMES	B-Algorithm
Type	I-Algorithm
91	I-Algorithm
.	O
</s>
<s>
By	O
the	O
late	O
1980s	O
,	O
new	O
designs	O
using	O
active	B-Architecture
electronically	I-Architecture
scanned	I-Architecture
arrays	I-Architecture
for	O
3D	O
scanning	O
were	O
becoming	O
more	O
widely	O
available	O
and	O
the	O
Martello	O
design	O
began	O
to	O
look	O
dated	O
.	O
</s>
<s>
In	O
response	O
,	O
Marconi	B-Device
began	O
an	O
upgrade	O
process	O
to	O
produce	O
the	O
S743	O
.	O
</s>
<s>
In	O
1988	O
,	O
Marconi	B-Device
was	O
part	O
of	O
wide-reaching	O
deal	O
with	O
Malaysia	O
which	O
delivered	O
two	O
S743	O
's	O
in	O
1992	O
.	O
</s>
<s>
Thailand	O
chose	O
the	O
S743	O
over	O
the	O
US-built	O
AN/FPS	B-Application
-117	I-Application
,	O
concluding	O
that	O
two	O
Martellos	O
would	O
provide	O
the	O
same	O
coverage	O
as	O
three	O
FPSs	O
.	O
</s>
<s>
Marconi	B-Device
introduced	O
the	O
S753	O
derivative	O
at	O
the	O
September	O
1992	O
Farnborough	O
Air	O
Show	O
.	O
</s>
<s>
In	O
1998	O
,	O
GEC-Marconi	O
and	O
Alenia-Finmeccanica	O
joined	O
to	O
produce	O
Alenia	O
Marconi	B-Device
Systems	O
.	O
</s>
<s>
In	O
1994	O
,	O
Marconi	B-Device
partnered	O
with	O
Ceselsa	O
(	O
today	O
known	O
as	O
indra	O
)	O
to	O
produce	O
a	O
new	O
version	O
of	O
Martello	O
for	O
the	O
Spanish	O
market	O
.	O
</s>
<s>
The	O
beam-forming	B-Algorithm
network	I-Algorithm
produced	O
nine	O
stacked	O
beams	O
for	O
altitude	O
measurements	O
.	O
</s>
<s>
The	O
number	O
of	O
vertical	O
beams	O
in	O
the	O
beam	B-Algorithm
forming	I-Algorithm
network	O
was	O
reduced	O
from	O
nine	O
to	O
eight	O
,	O
while	O
the	O
S723C	O
model	O
further	O
reduces	O
this	O
to	O
six	O
.	O
</s>
<s>
On	O
reception	O
,	O
pulse	B-Algorithm
compression	I-Algorithm
reduced	O
this	O
to	O
the	O
same	O
0.25µs	O
as	O
the	O
S713	O
.	O
</s>
<s>
Continued	O
improvements	O
in	O
solid	O
state	O
electronics	O
,	O
and	O
especially	O
microprocessors	B-Architecture
,	O
led	O
to	O
the	O
development	O
of	O
the	O
S743	O
,	O
a	O
product-improved	O
S723	O
.	O
</s>
<s>
The	O
primary	O
change	O
was	O
the	O
selection	O
of	O
a	O
new	O
transmitter	O
module	O
with	O
a	O
wider	O
bandwidth	B-Algorithm
,	O
130MHz	O
up	O
from	O
100	O
,	O
and	O
improved	O
reliability	O
.	O
</s>
<s>
The	O
signal	O
processing	O
system	O
was	O
also	O
upgraded	O
to	O
a	O
dramatically	O
more	O
powerful	O
system	O
using	O
an	O
array	O
of	O
4,000	O
INMOS	B-General_Concept
Transputers	I-General_Concept
.	O
</s>
