<s>
The	O
SIRE	B-Algorithm
radar	I-Algorithm
system	O
comes	O
mounted	O
on	O
top	O
of	O
a	O
vehicle	O
and	O
receives	O
signals	O
that	O
form	O
images	O
that	O
uncover	O
up	O
to	O
33	O
meters	O
in	O
the	O
direction	O
that	O
the	O
transmitters	O
are	O
facing	O
.	O
</s>
<s>
It	O
uses	O
a	O
GPS	O
and	O
Augmented	B-General_Concept
Reality	I-General_Concept
(	O
AR	O
)	O
technology	O
in	O
conjunction	O
with	O
camera	O
to	O
create	O
a	O
live	O
video	O
stream	O
with	O
a	O
more	O
comprehensive	O
visual	O
display	O
of	O
the	O
targets	O
.	O
</s>
<s>
The	O
SIRE	B-Algorithm
radar	I-Algorithm
is	O
part	O
of	O
a	O
long	O
generation	O
of	O
UWB	O
and	O
synthetic	B-Application
aperture	I-Application
radar	I-Application
(	O
SAR	O
)	O
systems	O
developed	O
by	O
the	O
U.S.	O
Army	O
Research	O
Laboratory	O
(	O
ARL	O
)	O
starting	O
in	O
the	O
early	O
1990s	O
.	O
</s>
<s>
Past	O
systems	O
include	O
the	O
railSAR	B-Algorithm
and	O
the	O
boomSAR	B-Algorithm
systems	O
as	O
well	O
as	O
the	O
more	O
recent	O
Spectrally	O
Agile	O
Frequency-Incrementing	O
Reconfigurable	O
(	O
SAFIRE	O
)	O
radar	O
system	O
.	O
</s>
<s>
The	O
SIRE	B-Algorithm
radar	I-Algorithm
was	O
eventually	O
transitioned	O
to	O
the	O
Communications	O
Electronics	O
Research	O
,	O
Development	O
and	O
Engineering	O
Center	O
(	O
CERDEC	O
)	O
at	O
Fort	O
Belvoir	O
,	O
VA	O
.	O
</s>
<s>
The	O
SIRE	B-Algorithm
radar	I-Algorithm
functions	O
primarily	O
as	O
a	O
method	O
of	O
assessing	O
the	O
surrounding	O
environment	O
and	O
determining	O
whether	O
the	O
path	O
being	O
traversed	O
is	O
safe	O
for	O
vehicular	O
navigation	O
.	O
</s>
<s>
In	O
contrast	O
,	O
the	O
SIRE	B-Algorithm
radar	I-Algorithm
can	O
penetrate	O
foliage	O
,	O
various	O
media	O
,	O
and	O
even	O
the	O
ground	O
to	O
detect	O
hidden	O
or	O
buried	O
IEDs	O
due	O
to	O
its	O
use	O
of	O
low-frequency	O
microwave	O
radiation	O
.	O
</s>
<s>
The	O
data	O
acquisition	O
cycle	O
for	O
the	O
SIRE	B-Algorithm
radar	I-Algorithm
consist	O
of	O
the	O
following	O
steps	O
:	O
</s>
<s>
The	O
receiver	O
array	O
picks	O
up	O
the	O
returning	O
radar	O
signals	O
,	O
which	O
are	O
then	O
digitized	O
by	O
the	O
field-programmable	B-Architecture
gate	I-Architecture
array	I-Architecture
(	O
FPGA	B-Architecture
)	O
acquisition	O
module	O
and	O
sent	O
to	O
the	O
central	O
computer	O
along	O
with	O
the	O
time	O
tag	O
information	O
from	O
the	O
GPS	O
receiver	O
.	O
</s>
<s>
The	O
transmitters	O
used	O
in	O
the	O
SIRE	B-Algorithm
radar	I-Algorithm
are	O
transversal	O
electromagnetic	O
(	O
TEM	O
)	O
horns	O
that	O
generate	O
short	O
,	O
1	O
nanosecond-long	O
radar	O
pulses	O
with	O
a	O
pulse	O
repetition	O
frequency	O
(	O
PRF	O
)	O
of	O
1MHz	O
and	O
a	O
frequency	O
band	O
from	O
300	O
to	O
2500MHz	O
.	O
</s>
<s>
The	O
receivers	O
used	O
in	O
the	O
SIRE	B-Algorithm
radar	I-Algorithm
are	O
Vivaldi	O
notch	O
antennas	O
which	O
are	O
arranged	O
in	O
a	O
uniform	O
linear	O
array	O
that	O
span	O
the	O
width	O
of	O
the	O
vehicle	O
.	O
</s>
<s>
In	O
order	O
to	O
prevent	O
radio-frequency	O
interference	O
(	O
RFI	O
)	O
from	O
outside	O
sources	O
,	O
such	O
as	O
radio	O
,	O
TV	O
and	O
wireless	O
communication	O
signals	O
,	O
in	O
the	O
radio	O
frequency	O
band	O
,	O
the	O
SIRE	B-Algorithm
radar	I-Algorithm
employs	O
several	O
techniques	O
to	O
suppress	O
or	O
extract	O
these	O
signals	O
from	O
the	O
UWB	O
radar	O
data	O
.	O
</s>
<s>
Instead	O
of	O
conventional	O
methods	O
of	O
screening	O
like	O
the	O
notch	O
filtering	O
approach	O
,	O
the	O
SIRE	B-Algorithm
radar	I-Algorithm
narrowband	O
and	O
wideband	O
RFI	O
screening	O
process	O
involve	O
averaging	O
repeated	O
measurements	O
from	O
the	O
same	O
range-profile	O
.	O
</s>
<s>
The	O
mounted	O
SIRE	B-Algorithm
radar	I-Algorithm
system	O
comes	O
in	O
two	O
modes	O
depending	O
on	O
its	O
orientation	O
on	O
top	O
of	O
the	O
vehicle	O
.	O
</s>
<s>
An	O
alternative	O
is	O
the	O
side-looking	O
mode	O
,	O
where	O
the	O
antenna	O
frame	O
that	O
supports	O
the	O
SIRE	B-Algorithm
radar	I-Algorithm
system	O
is	O
rotated	O
90	O
degrees	O
and	O
the	O
direction	O
of	O
the	O
radar	O
is	O
perpendicular	O
to	O
the	O
path	O
of	O
the	O
vehicle	O
.	O
</s>
