"Radar flashlight" lets cops spot people through walls
UniSci - Daily University Science News New Flashlight Sees Through Doors As
Well As Windows April 16, 2001
Police officers serving a warrant or searching for a suspect hiding inside a
building could soon have a new tool for protecting themselves and finding
the "bad guy."
A prototype device called the RADAR Flashlight, developed at the Georgia
Tech Research Institute (GTRI), can detect a human's presence through doors
and walls up to 8 inches thick.
The device uses a narrow 16-degree radar beam and specialized signal
processor to discern respiration and/or movement up to three meters behind a
wall. The device can penetrate even heavy clothing to detect respiration and
movements of as little as a few millimeters. "We believe the RADAR
Flashlight potentially will be useful to police officers in ambush
situations," says Gene Greneker, the GTRI principal research scientist who
led the development of the device. ".... It is a force multiplier and a
safety enhancement tool."
The RADAR Flashlight is undergoing further modification and testing for the
next six months. The Georgia Institute of Technology has filed a provisional
patent for the device, which could become commercially available to law
enforcement officials within a couple of years if the university licenses
the technology to a manufacturer.
With funding in 1998 from the National Institute of Justice (NIJ), a
division of the U.S. Justice Department, Greneker and his team took the
RADAR Flashlight from a bulky three-part prototype to a self-contained unit
that weighs about 7 pounds. The NIJ tested the device last year at the
National Law Enforcement Corrections Technology Center in Charleston, S.C.,
and suggested further modifications. Work on those changes is expected to
begin this spring with additional funding from the NIJ.
"We will be modifying the RADAR Flashlight based on what law enforcement
officials told us from the tests," Greneker says. "For one thing, they said
it makes too much noise when it locks onto a wall (to scan). Also, for use
by SWAT teams, the RADAR Flashlight needs to be operated by remote control.
So we plan to put the RADAR Flashlight on a tripod at least 25 feet away
from a wall and steer it by remote control to the part of the wall we're
interested in scanning."
When these modifications are complete, the RADAR Flashlight will undergo
more rigorous testing in various environmental conditions.
In its current form, the RADAR Flashlight operates in the following manner:
The user holds the device with a pistol-grip handle, pulls a trigger, and
the device runs a 3-second self-test to verify that it is properly
functioning. The user sees the results as a bar graph on a small LED display
built into the device.
Then the user presses the device against a wall, pulls the trigger, and
within 3 seconds the system automatically spaces itself from the wall at a
distance designed for best performance.
The RADAR Flashlight's narrow radar beam sends out a pulse of
electromagnetic energy, then detects the return signal, which is read by
high-speed signal processing technology that quickly delivers bar-graph
results to the user's display.
As the person on the other side of the wall breathes, the bar-graph display
rises and falls with a rhythmic response.
Research that evolved into the RADAR Flashlight began at GTRI in the
mid-1980s with the patenting of a frequency-modulated radar for remotely
checking vital signs of soldiers wounded on the battlefield before risking
medics' lives to save the injured.
This early technology also was tested for its ability to monitor vital signs
of soldiers clothed in chemical or biological warfare suits, without
requiring them to risk contamination by removing the protective gear.
Today, a technical challenge remains for researchers working on the RADAR
Flashlight. "We have one problem," Greneker says. "This instrument is so
sensitive to motion that if you don't hold it still enough, it will detect
its own self-motion. If we can overcome this, it would be the Holy Grail,
and interestingly enough, we think we know how to solve this problem with
Bill Deck of the National Law Enforcement Corrections Technology Center
cited the RADAR Flashlight's stability and LED display as key issues to
target before the device is commercialized.
"The RADAR Flashlight has some potential," Deck said. "There is some
interest from police departments. They gave us about 25 scenarios in which
the device could be useful. For example, when an officer goes to serve a
warrant, it could let him know that someone is standing behind the door,
maybe waiting to ambush him."
Greneker says he is encouraged by interest from police departments and hopes
the RADAR Flashlight will be commercialized soon.
"Our target sales price is $1,000 to $1,500 per device," Greneker says.
"That price range is important to police departments because they usually
don't have a lot of money to spend."
Meanwhile, other companies have developed a micro-impulse type of radar
intended for the same purposes as the RADAR Flashlight. The micro-impulse
radar spreads energy over a broad band of frequencies using a technique not
yet approved by the Federal Communications Commission, Greneker says.
The RADAR Flashlight operates on a narrow frequency in a license-free band,
he adds. It can detect motion and/or respiration through brick, wood,
plasterboard, glass and concrete. It will not work in water or on metal
structures, such as mobile homes, because these materials are electrical
For those concerned about radiation exposure from the flashlight, Greneker
says the emission is very small -- meeting national standards for the
maximum human exposure limits. It emits about the same amount of radiation
as a person receives when standing in front of a microwave-actuated door in
a store. - By Jane M. Sanders
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