<s>
A	O
radar	B-Algorithm
detector	I-Algorithm
detector	I-Algorithm
(	O
RDD	O
)	O
is	O
a	O
device	O
used	O
by	O
police	O
or	O
law	O
enforcement	O
in	O
areas	O
where	O
radar	B-Application
detectors	I-Application
are	O
declared	O
illegal	O
.	O
</s>
<s>
Radar	B-Application
detectors	I-Application
are	O
built	O
around	O
a	O
superheterodyne	O
receiver	O
,	O
which	O
has	O
a	O
local	O
oscillator	O
that	O
radiates	O
slightly	O
.	O
</s>
<s>
The	O
VG-2	B-Algorithm
Interceptor	O
was	O
the	O
first	O
device	O
developed	O
for	O
this	O
purpose	O
,	O
although	O
more	O
current	O
technology	O
such	O
as	O
the	O
Spectre	O
III	O
(	O
Stalcar	O
in	O
Australia	O
)	O
is	O
now	O
available	O
.	O
</s>
<s>
This	O
form	O
of	O
"	O
electronic	O
warfare	O
"	O
cuts	O
both	O
ways	O
and	O
since	O
detector-detectors	O
use	O
a	O
similar	O
superheterodyne	O
receiver	O
,	O
many	O
early	O
"	O
stealth	O
"	O
radar	B-Application
detectors	I-Application
were	O
equipped	O
with	O
a	O
radar-detector-detector-detector	O
circuit	O
,	O
which	O
shuts	O
down	O
the	O
main	O
radar	O
receiver	O
when	O
the	O
detector-detector	O
'	O
s	O
signal	O
is	O
detected	O
,	O
thus	O
preventing	O
detection	O
by	O
such	O
equipment	O
.	O
</s>
<s>
In	O
the	O
early	O
1990s	O
,	O
BEL-Tronics	O
,	O
Inc	O
.	O
of	O
Ontario	O
,	O
Canada	O
(	O
where	O
radar	B-Application
detector	I-Application
use	O
is	O
prohibited	O
)	O
found	O
that	O
the	O
local	O
oscillator	O
frequency	O
of	O
the	O
detector	O
could	O
be	O
altered	O
to	O
be	O
out	O
of	O
the	O
range	O
of	O
the	O
VG-2	B-Algorithm
Interceptor	O
.	O
</s>
<s>
Today	O
,	O
practically	O
every	O
radar	B-Application
detector	I-Application
on	O
the	O
market	O
is	O
immune	O
to	O
the	O
VG-2	B-Algorithm
Interceptor	O
.	O
</s>
<s>
The	O
VG-2	B-Algorithm
is	O
no	O
longer	O
in	O
production	O
.	O
</s>
<s>
The	O
Spectre	O
III	O
detected	O
almost	O
every	O
radar	B-Application
detector	I-Application
certified	O
for	O
operation	O
in	O
the	O
United	O
States	O
by	O
the	O
Federal	O
Communications	O
Commission	O
as	O
of	O
December	O
2004	O
.	O
</s>
<s>
However	O
counter	O
technology	O
has	O
evolved	O
rapidly	O
,	O
so	O
that	O
by	O
July	O
2008	O
,	O
even	O
budget	O
radar	B-Application
detectors	I-Application
were	O
able	O
to	O
avoid	O
detection	O
by	O
the	O
device	O
.	O
</s>
<s>
Radar	B-Application
detector	I-Application
manufacturers	O
produce	O
some	O
models	O
undetectable	O
by	O
the	O
Spectre	O
Elite	O
beyond	O
a	O
distance	O
of	O
a	O
few	O
inches	O
,	O
making	O
them	O
immune	O
in	O
real-world	O
situations	O
.	O
</s>
