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Air Beat Magazine - Journal of the
Airborne Law Enforcement Association
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Legal Aspects of Forward-Looking Infrared Technology
Understanding Probable Cause
By Judge Joseph J. Bruzzese Jr.
Jefferson County Ohio Common Pleas Court
Thermal imaging has been used for sometime now to
establish probable cause to search suspected indoor marijuana growing
operations. The difficulty comes in using thermal imaging in a way that
gathers probable cause, but does not constitute a search in and of itself
before the warrant is issued. Whether and when FLIR or thermal imaging is a
search in and of itself has been the subject of considerable litigation.
To understand this litigation one must first know what a
search is. A search occurs where the government invades or inspects an area
that has two characteristics. First, the defendant must have manifested a
"subjective expectation of privacy," that is, the defendant himself believes
the area to be private. Second, this expectation must be "reasonable" in the
sense that society is willing to recognize the expectation as reasonable. If
a place fails either of these tests, then an invasion or inspection of that
place is not a search and does not require a search warrant.
The next concept, which must be understood, is that of
probable cause. Probable cause has been defined as a "fair probability that
contraband or evidence of a crime will be found in a particular place."
Note, that it is a fair probability and not a fair "possibility." The whole
idea of the search warrant requirement under the Fourth Amendment is to
prevent the government from stopping, inconveniencing or otherwise hassling
the innocent which necessitates requiring the "probability" of guilt rather
than mere "possibility."
The history of FLIR and thermal imaging in the law
actually began with an airborne camera in the case of Dow Chemical Co v.
U.S. 476 U.S. 227, 106 S.Ct. 1819 (1986). In that case, government officials
overflew a Dow Chemical plant with a technically sophisticated mapping
camera that takes 3D photos when viewed through a special apparatus. The
camera captured illegal activity at the Dow plant.
Dow Chemical claimed that the results of the photo over
flight were the product of an illegal search and were illegally obtained.
The court allowed the photo over flight even though the Police used
technically sophisticated equipment because the area photographed was a
business and not a home. The court reasoned that the expectation of privacy
in a business or an open field is less than the expectation of privacy in a
home and allowed the evidence. The test laid down for an open field or a
business was the "intimate details" test. So long as "intimate details" are
not revealed the surveillance of a business is not a search.
The legal distinction between a business and a home
survives to this day and the rules of surveillance remain different for
each. Dow Chemical v. United States is still good law today and is often
cited in FLIR cases.
The concept of Dow Chemical was applied to thermal
imaging of a farm in U.S. v. Ishmael 48 F 3d 850 (see 5th Circuit, 1995). In
that case, DEA Agent Paul Black kept a farm building under surveillance on
foot and through FLIR equipped overflights. The building, which was far from
the house, was hot as were some other items around the building. No illegal
activity was actually observed. The thermal imaging along with Ishmael’s
purchases and the water use of the building combined to establish probable
cause for a search warrant revealing 770 marijuana plants and some firearms.
At trial, the court suppressed the evidence on the ground
that the FLIR overflight was a warrantless search and without that evidence
there was no probable cause for the warrant that issued. The government
appealed.
The government analogized the situation to "plain view"
arguing that the heat was in plain view. It also drew an analogy between
waste heat and the common practice of the police inspecting garbage.
Finally, the government argued that FLIR, detecting heat, is no different
from a drug dog, which hits on the odor of illegal drugs.
What won the day for the government was the basic
definition of "search" and the Dow Chemical case. The Appeals Court held
that even though Ishmael went to great lengths to hide his operation and
probably had a subjective expectation of privacy, that his subjective
expectation was not reasonable. The court held that the farm buildings away
from the home were the same as an industrial site or "open field" with a
reduced expectation of privacy. This reduced expectation of privacy allows
for surveillance so long as it does not reveal "intimate details" as
described in Dow Chemical. Because thermal imaging detects only heat on the
outside of the building, it does not reveal intimate details such as whom or
how many people are inside the building.
In United States v. Robinson 62 F 3d 1325 (11th
Circuit)(1995), the Court of Appeals erroneously applied the same concepts
announced in Dow Chemical to a home and allowed FLIR surveillance of
Robinson’s home, even without a search warrant. Such remained the state of
the law until it was overruled by the U.S. Supreme Court in Kyllo v. United
States.
In Kyllo v. United States 533 U.S. 27, 121 S.Ct. 2038
(2001), Kyllo was a 5/4 decision by the U.S. Supreme Court with Stephen,
Rehnquist, O’Conner and Kennedy dissenting. It is important to note that
Rehnquist and O’Conner are no longer with the Court and that a similar issue
may be decided the same way by an even wider margin today.
In Kyllo, the police used thermal imaging on a triplex
home where Kyllo lived and where the police suspected he was growing
marijuana. This evidence led to a search warrant, which led to the discovery
of an indoor marijuana growing operation. The trial court and the Court of
Appeals both allowed the warrantless thermal imaging evidence using the
"intimate details" test from the Dow Chemical case as applied in U.S. v.
Robinson. The case eventually found its way to the U.S. Supreme Court. The
U.S. Supreme Court took a different view of the Dow Chemical "intimate
details" test because this was a house and not an industrial site or an open
field. The expectation of privacy in a home is far greater and the
reasonableness of that expectation is also greater where applied to a home.
The government tried to draw a distinction between "off-the-wall technology"
and "through-the-wall surveillance" reasoning that what comes off the wall
(i.e. heat) is different from what can be seen through the wall (i.e. people
and things) and that thermal imaging exposed no "intimate details" even
though this was a home.
The Court rejected that concept finding that all details
are "intimate details" with respect to a home. The Court essentially held
that the heat coming off of the wall originated inside the home and that
because all details are intimate details, the use of "sense-enhancing
technology" was a search and cannot be done to a home without a warrant.
The reason that a court makes a particular decision is
often as important as the decision itself. This is particularly true in
Kyllo where the Court hinted at an expiration criteria that will eventually
render Kyllo obsolete and inapplicable. The hint comes in the following
paragraph:
"We think that obtaining by sense-enhancing technology
any information regarding the interior of the home that could not otherwise
have been obtained without physical ‘intrusion into a constitutionally
protected area’....constitutes a search - at least where (as here) the
technology in question is not in general public use." (emphasis added)
This paragraph provides a "sundown provision" of sorts on
the Kyllo decision. Recall that surveillance is not a search unless it
invades an area where there exists the subjective and objective expectation
of privacy. The Court is telling us that when thermal imaging technology
becomes so commonplace as to become expected, then the Kyllo decision may no
longer be applicable.
As the cost of thermal imaging comes down and the public
at large begins to use it, the "sundown" criteria announced by the Supreme
Court will begin to occur. The earliest stages of "general public use" have
already started. Already, some auto manufacturers are offering thermal
imaging for night driving. Hunters have long had access to thermal devises
for locating downed game and recently a privately owned FLIR equipped
helicopter located and rescued a lost girl. Just as GPS went from unheard of
to commonplace in about 20 years, so will thermal imaging and Kyllo will
begin to expire on its own terms.
FLIR IDENTIFICATION OF PEOPLE & THINGS
For more than 30 years, various police agencies have used thermal imaging
for night surveillance. These activities eventually find their way into
court where the police agency tries to link a particular defendant, vehicle,
airplane or other object to a particular thermal image. These identification
activities have led to a long line of cases that are evolving in the
direction of putting more and more confidence in the ability of thermal
imaging to identify objects and things.
U.S. v. Kilgus 571 F 2d 508 (9th Circuit) (1978) is an
early case that helped define thermal imaging identification issues. Kilgus
remains important and is still cited today.
In Kilgus, Customs officials tracked an airplane by radar
and by FLIR equipped aircraft until it landed on Lost Lake, a dry lakebed
near Las Vegas. The Customs plane identified the subject aircraft on the
lakebed as a DC 3 but then departed in pursuit of several land vehicles. The
Customs plane then returned to Lost Lake only to find that the DC 3 had
departed. A short while later, a DC 3 piloted by Kilgus landed at Las Vegas
International Airport and the government sought to prove that the DC 3
landed by Kilgus was the same DC 3 that delivered marijuana to Lost Lake.
In that case, the court discussed the test that any
technology must pass before it is admissible in the courtroom. Simply
stated, the technology and the principle upon which it is based "must be
sufficiently established to have gained general acceptance in the particular
field to which it belongs." This is important because it allows a particular
field of technology to control the use of that technology in the courtroom.
To be admissible, the technology must be generally accepted not by judges
and lawyers but by the technicians who use it.
Using that test, Kilgus then discussed two levels of
identification. The first level is "generic identification;" that is, the
ability to distinguish a plane from a boat or even a Lear Jet from a DC 3.
The next level of identification is "unique identification" which is the
ability to distinguish between two DC 3s or two Lear Jets. The court found
that the state of the art in thermal imaging at the time was generally
accepted in the field for generic identification but not unique
identification. The government was not able to prove that the two DC 3’s
were the same.
As technology improved, so did legal reliance on thermal
imaging. In U.S. v Porter 701 F 2d 1158 (6th Circuit)(1983) the court
allowed a FLIR operator to identify a plane not only as a twin-engine low
wing plane but also as a Navajo. Other evidence in that case corroborated
the FLIR observations.
In U.S. v. Santa-rosa 32 F 3d 860 (1st Circuit) (1998) an
airborne FLIR operator tracked a vessel suspected of delivering cocaine
until it beached in Puerto Rico. Four persons ran from the vessel into the
mangroves and were no longer visible. Customs officials arrived by
helicopter and the National Guard arrived by boat. Three (3) people were
arrested in those same mangroves. At trial, the airborne FLIR operator was
permitted to testify that in his opinion the three people arrested in the
mangroves were three of the four that he had seen escape into the mangroves.
While this case comes close to "unique identification," that term was never
discussed. Further, this identification was corroborated by the fact that
the mangroves were very remotely located and that no other persons were
likely to be present. It is unlikely that the court would have allowed this
identification in a more populated area. Still, this case comes very close
to allowing "unique identification".
There is no doubt that a court would permit a FLIR
operator to testify with respect to unique identification if it was done in
a way that proved that capability in the equipment. Two scenarios come to
mind. The first and the easiest is the scenario where the subject has some
distinguishing feature that is clearly visible on the FLIR scene, such as a
particularly bright light or off-color light. The second and more difficult
scenario would involve numerous images of numerous subjects (i.e. DC 3s)
under different circumstances with an operator who can demonstrate his
ability to distinguish one from the other. This second scenario would
require considerable pre-trial testing and experimentation, which would be
time consuming and expensive and may not yield the desired results with
today’s technology. The newest equipment may well be capable of passing such
a test today in the right hands. There will eventually be a first case
allowing unique identification and it might as well be yours.
(Back to top)
The Next Generation of Airborne Imaging Technology
by Brian Spillane
FLIR Systems Inc.
As with other high-tech products like computers and cell
phones, airborne imaging systems are constantly being pushed to the next
level. With computers it’s, "I want it faster." With cell phones, "I want it
smaller." With airborne law enforcement imaging systems it’s "I want to see
more." More detail, more distance, more information that can lead to
apprehensions and arrests.
To meet the tactical flight officer’s (TFO’s) call to see more, there are
five main areas where airborne imaging systems are advancing. System range,
infrared (IR) resolution, color camera resolution, alternative night vision
technologies and integrated systems are all being enhanced to make airborne
imaging a more effective law enforcement tool.
System Range
Range is defined by how far a camera can see. It’s best expressed in
focal length (usually in mm) and Narrow Field of View (NFOV), which is
expressed in degrees. The longer the lens and the narrower the NFOV, the
further a system can see. Systems like the model 2000 (circa 1984) maxed out
at a 90 mm lens and six degree NFOV. Current generation U8500XR systems,
with a 450 mm lens and 1.2 degree NFOV, have five times the range in a
turret that’s half the size and weight. High-end systems like the UltraMedia
HD and Star Safire HD see even further still.
A longer lens gets a TFO closer to the action, giving him
the ability to gather more information faster, and faster information might
mean the difference between apprehending a suspect or not. Improved range
also can make a perimeter search more efficient. If a TFO can eliminate
targets from the air because he can zoom in close enough to properly
identify false hot spots during a FLIR search, there’s less time wasted
sending ground forces to identify "possibles." Improved range also can
improve officer safety. It can mean the difference between a TFO telling
ground forces, "the suspect may be holding an object" and "the suspect has a
gun."
Range also increases standoff distance. This can improve
safety as well, enabling a crew to fly higher. But it also can add
surveillance capability to the repertoire of an air unit that currently
can’t operate their camera far enough away from a suspect to avoid
visual/audio detection of the aircraft. In the past, patrol systems had
short focal lengths, surveillance systems had long focal lengths and never
did the two meet. With the availability of small gimbals offering focal
lengths on the order of 450 mm, that is no longer necessarily the case. A
single compact camera system can now fly patrol missions at 600 feet and
double as a surveillance platform at more than 4,000 feet. Of course,
current generation high-end systems can provide even more standoff distance
for completely covert missions.
IR Resolution
Range would mean nothing without resolution. You can put the longest
lens in the world on a detector, but if it doesn’t have the ability to
resolve the detail it’s worthless.
A simple way of talking about detector resolution is how
many pixels it has. Early generation IR detectors were scanning arrays, with
only one or a few pixels that were scanned to make a composite image. It
wasn’t very high resolution by today’s standards, but it got the technology
off the ground. It wasn’t until the introduction of the focal plane array (FPA)
that IR imaging made a quantum leap forward. Current generation IR FPAs are
typically at least 320 x 240 pixels, but 640 x 480 arrays also are common.
Novel higher resolution detectors may also incorporate "pixel-shift"
technology that moves the detector array up and down and left to right to
give a greater resolution than the basic chip can accomplish on its own. The
result is an IR image that looks more like fine black & white photography
than the gray scale image most people associate with an IR sensor. One
mega-pixel IR detectors (1K x 1K FPA) are soon to be released.
Color Camera Resolution
The same concept of resolution applies to the color camera. But a
charge-coupled device chip with more pixels sees more detail.
The term that is thrown around to define color resolution
these days is high definition (HD). However, all HD is not created equal.
There is 1080i and 720p. The 1080i HD has an interlaced signal, a holdover
from the early days of television, where networks had to split the signal
into two pieces in order to transmit it with the limited bandwidth of the
day. The two signals were reassembled on the receiving end – in the TV. With
progressive signals, as in 720p HD, what you see is what you get, one full
frame at a time. Interlacing has an inherent distortion – especially with
quickly moving targets. Progressive images do not. Albeit with less pixels
(720 vs. 1080), 720p is far better with moving targets. Both 1080i and 720p
are used in current generation, high-end imaging systems.
Alternative Night Vision Technologies
IR has always been synonymous with night vision in airborne law enforcement.
Image intensifier technology, the familiar green image from night vision
goggles (NVG), has also been used in airborne gimbals for several years, but
there are new low-light technologies available and even more on the horizon.
These new technologies generally employ some form of electron bombardment
technique. With this technology, very low levels of light particles, known
as photons, excite a special detector chip to generate a signal. It’s
similar to NVGs, in that it magnifies extremely low levels of visible light,
but that’s where the similarity ends.
With electron bombardment, the signal is digital, whereas
NVG-type images are analog. This gives two distinct advantages to electron
bombardment. First, a digital signal is cleaner. It doesn’t have the video
noise that accompanies analog signals. Second, a digital signal can be
manipulated electronically. One type of manipulation is laser illuminated
viewing and ranging (LIVAR). LIVAR has the ability to illuminate targets
from extremely long distances. When used in conjunction with an electron
bombardment sensor, night vision standoff ranges can become miles, a
distinct advantage for counter-drug or homeland security missions where the
need to stay covert is a priority.
Integrated Systems
The last area where major strides are being made with regard to airborne
imaging is with integrating moving map and camera systems. Until recently,
moving maps and cameras were two completely separate pieces of gear. But the
ability to have a map "follow" a camera, and to even have the map control
the camera, have been on the short list of TFO desires for a while.
Camera manufacturers has been providing pointing data for
their turrets for over a decade, and moving map manufacturers have been able
to tap into that data stream to track a turret much in the same way that
searchlights have been slaved to cameras. However, without reliable aircraft
heading reference data, the accuracy of the map/camera interface left
something to be desired. Common aircraft-installed attitude and heading
reference systems (AHRS) combined with onboard GPS often lack the ability to
provide information fast enough to ensure accuracy of cameras zoomed into
the very narrow fields of view.
With the incorporation of an inertial measurement unit (IMU),
aircraft heading reference data can be calculated, thereby increasing the
map/camera accuracy to an acceptable level. The highest performing systems
are designed with IMUs embedded in the camera and include a stand-alone GPS
solution not reliant on aircraft avionics. Fully integrated systems are now
available where a moving map not only accurately follows a camera’s view
(for fire mapping or tracking a mission or pursuit, for example), but also
guides and controls, or cues, where a camera points. The result is
hands-free operation for a TFO once the camera has been commanded to hold to
a specific geo-location or target. With such an automated cueing feature, a
TFO might even enter a street address from across town, and the map will
direct and hold the turret on that location before it is visible. The TFO is
then free to perform other tasks on the way to the call, and the camera will
be waiting for him, on target, when he’s ready to begin his perimeter
search. The reduction in workload that an IMU/GPS equipped camera/map system
provides can be substantial.
It’s a very exciting time for airborne imaging, as law
enforcement aviators increase their use of this technology. The goal is a
more efficient and effective TFO.
(Back to top)
Seeing Is Believing
Microwave Downlinks For Airborne Law Enforcement
By Steve Yanke
Broadcast Microwave Services
If you’re operating an aerial observation platform, using
a camera ball and reporting to ground personnel without a microwave downlink
system, somebody’s not getting the whole picture.
Have you ever had an incident where you tried to describe what you saw from
your aircraft to someone on the ground, and they just didn’t get it? Did you
think to yourself, if they could have just seen what I saw they could have
reached out differently and changed the outcome of the incident? With a
microwave downlink, you can show them exactly what you see.
Video is a universal language. Say you started your
career in SWAT; you will have no trouble describing a scene to a SWAT team.
But when you have to describe a fire to a Battalion Chief, or a flooded
bridge to an engineer, or a gas cloud to an emergency management assessment
team, your words may not contain adequate descriptions for them to act.
Video transcends training and language barriers, and
microwave downlinks are the link for the video between your aircraft and
those on the ground. Live video makes mutual aid a snap and increases the
value of your contribution to all those that can see it. But the trick is to
get a microwave receiver to the person, wherever they are, when they need
it.
Transmission Signals
There are two types of transmit systems for aircrafts: the omni antenna and
the high gain antenna. The high gain antenna goes further, but it can only
go in one direction and cannot be pointed towards multiple receivers. The
omni-directional antenna can.
Once you’ve established the direction of your signal, you
have to decide how far you need it to go. Short, medium and long-range are
the three types of microwave downlink systems. The differences between them
come from the antennas used on the send and receive sides.
There are several important physical considerations that
must be taken into account when designing a microwave downlink. First, you
must have enough power to get the signal from the transmit antenna to the
receive antenna. Transmit power is typically limited by the FCC or by the
antennas used in the transmitter design. Next, the microwave downlink
requires line of sight in order to maintain the link. And last but not
least, multi-path is the enemy to a good microwave link.
Antennas are used to amplify the signal, and the antenna
coverage pattern determines where the signal is sent. The selection of the
antennas is the most important part of designing the microwave system. If
you use the wrong antenna for the wrong application, it can make the system
impossible to use.
Omni antennas transmit or receive in 360 degrees. More
than likely, you see more than one omni, or dipole, antenna every day.
Cellular phones and car radios are two of the more common applications. They
are simple to use because they do not require a lot of pointing.
High gain antennas are focused like a flashlight beam and
require pointing. By focusing the energy, they go further. Satellite dish
and TV antennas are examples of high gain antennas.
Line of sight (LOS) means that you must be able to see
the receive antenna from the transmit antenna. When you consider the
curvature of the earth, this means the farther you want to send the signal,
the higher you must fly. Whenever you can, put the receive antenna as high
as possible. This will allow you to maintain LOS at a lower aircraft
altitude. Buildings can block the signal, and tree lines and mountains also
affect the height you need to maintain for LOS transmission. A good rule of
thumb is when the receive sight looses signal, fly higher.
Multi-path is caused by reflected signals. These
reflected signals are collected by the receive antenna and either add up
constructively or destructively. More times than not, the multi-path signal
will be destructive. In the real world, when transmitting from a moving
platform like an aircraft, there will always be multi-path, and you will
have to live with it. You can minimize multi-path by locating the transmit
antenna as far away from reflecting surfaces as possible and by using high
gain antennas on the receive sites.
Licensing & Frequencies
You must obtain a license from the FCC to operate a microwave downlink. This
can be the most difficult thing to do and the first thing that is overlooked
when considering a downlink system.
You can never start this process early enough. There are
companies that specialize in working with the FCC in getting licenses. For a
nominal fee, these companies will assist you in streamlining the licensing
process. Some agencies may have the properly educated personnel that can
obtain a license without the aid of these licensing companies.
You also need to know what frequencies you can use before
you can purchase equipment. The spectrum is congested, and if you live near
a heavily populated area like New York City or Los Angeles, the frequencies
are used up.
The FCC controls what frequencies are used for what
application. There are three frequency bands that can be used by the law
enforcement community for microwave downlinks from an airborne platform. The
frequency bands are 2.5, 4.9 and 6.4 GHz.
The 2.5 GHz band was first reserved for broadcasters and
ENG microwave paths. Law enforcement requested a waiver to set up temporary
surveillance links, and, in a case-by-case scenario, the broadcasters
allowed the waiver. Once the precedent was set, the law enforcement
community then went directly to the FCC and asked for another waiver to put
the microwave links on aircraft. Once this happened, the broadcasters
reconsidered the application and quit approving the licenses. When using
this band, the law enforcement community must get approval from the
broadcasters and is second in line to other broadcasters. Another problem
with the 2.5 GHz band is that the FCC has allowed low power, unlicensed
radios onto this band. Wireless 2.4 GHz phones, LANs and WANs are very
popular and have proliferated in many areas.
About four years ago, the FCC opened up 50 MHz of
bandwidth from 4.95 to 4.99 GHz. The 4.9 GHz band was set aside for law
enforcement and public safety mobile use only. The intended use for this
spectrum was to send large data files, like fingerprints and mug shots, out
to squad cars. The one problem was that the wording from the FCC excluded
airborne use. This was to limit exposure of police-generated signals to deep
space listening stations that were on the same frequencies. The FCC felt
that as long as the law enforcement transmitters were on the ground and
limited in power, they would never affect the research sites with large high
gain antennas that were pointed into the sky listening for ET to phone home.
The only way you can obtain a license in the 4.9 GHz band
for airborne use is to apply for a waiver. You must be far enough away from
research sites to ensure your signal does not interfere with them. It is
possible to get the waiver, but it takes time, and you may have power and
altitude restrictions on your license based on where you are located.
The 6.4 GHz band is open for industrial, mobile microwave
links. In this band, the law enforcement community is on equal ground with
all other users. But that is a double-edged sword. It is important to get in
first and stake out a home channel for your agency. There are frequency
coordinators in all areas of the U.S., and their job is to make sure
everyone is licensed and using the frequencies without transmitting on top
of other users.
Digital Versus Analog
Digital microwave downlinks are a relatively new technology. They use
coded orthogonal frequency division multiplexing (COFDM). COFDM is the most
robust transmission scheme available. Digital systems are more expensive,
use more power and are heavier than analog systems.
The biggest benefit to the end user of the digital
systems is that it does not require line of sight for a good video picture.
It does require a favorable reflected signal, which means that the signal
has to be powerful enough to reflect off of enough surfaces to get from the
transmit antenna to the receive antenna. There is no reliable way to predict
the success of a reflected microwave path. The best way is to try it. If it
works, great, if not, a digital system will still outperform the analog
system in the same conditions.
Digital downlinks are the wave of the future. If you can
afford digital and don’t have to work with other existing analog systems,
purchase a digital system. However, cost, weight, and existing analog
equipment are a few of the reasons to stick with analog downlinks.
Analog microwave systems have been around for over 25
years. The technology (FM modulation) is proven, and the pricing is mature.
Analog signals are limited to LOS and are susceptible to multi-path,
although they are still effective.
"We had a march on immigration laws in town where we used
our helicopter with our [analog] downlink and sent the feed to our
commanders in the mobile command post," said Lt. Frank Peck of the Nebraska
State Patrol Air Wing. "They were amazed at the picture and the fact that we
never lost the signal. I was informed that they thought that as we moved the
signal, it would come and go, and it never did. I believe that after today,
we will be purchasing fixed sites because the system worked great."
(Back to top)
Throw Away The Paper
The Evolution of Moving Map Technology
By Lon Arnold, Becker Avionics and
Greg Taylor, Flight Management Systems
Although moving maps are a fairly recent addition to the
law enforcement aviator’s toolbox, they have quickly become an indispensable
tool in the busy cockpit.
Some pilot's say that maps are more useful than thermal
imaging. They go on to explain that thermal imagers do little good if you
can’t find the right address to begin searching. There was a time when a
flight officer was so familiar with the city that he could direct you to the
correct street with no hesitation. But the rapid growth of today’s cities,
coupled with developers’ propensity to name entire subdivisions with
like-sounding streets, has made knowing every address impossible.
There are still many aviation units today that use the
good old paper maps. They are cheap, simple to operate and usually get the
job done – eventually. The disadvantage to paper maps is speed. If it took
you just 30 seconds to locate an unfamiliar address with a paper map, you
could have been flying for 30 seconds in the wrong direction. With
helicopter response times averaging less than two minutes, losing a minute
makes a huge difference.
Moving maps first began to appear as additional features
on some GPS devices as a tiny aircraft icon creeping across an even tinier
screen. The first maps contained only aeronautical information (airport
identifiers and the like), which was very useful for going cross-country but
of little or no help with locating an actual address.
One of the first moving maps designed for police work was
developed in 1996. It had a very basic search capability, but it got you on
the right street and close to the target address. You weren’t sure which
house you were looking for, but you knew within a few houses where to look.
The main advantage was speed. You had the direction to fly and distance to
the target address within seconds, repeatedly.
The next generation of moving maps employed raster maps.
They look like a paper map and have the aircraft icon centered on the screen
with the aeronautical chart or topographical map rolling along under it.
These could be displayed on the thermal imaging screen, which made them
large enough to be readable and very useful. Search capabilities improved to
get you closer to an exact address, and many additional features began to
appear. So many features developed that a training course can be required to
learn all of the capabilities.
Whereas a raster map can be thought of as a paper map
scanned into a computer, more advanced versions include vector graphics,
which is information created mathematically from raw data. When raster and
vector data is combined, they can provide situational awareness only dreamed
about just a few years ago.
Vector airspace or property data, for example, can be
displayed over a raster street map. This way it is possible to know what
radio frequencies you need to communicate with ATC or in the case of
property data, it is possible to know the phone number of the house you are
looking at. Custom data bases can be built from customer supplied data to
meet an agency’s needs.
The latest advancement to moving maps is the use of
geographic information systems (GIS) data. GIS data is composed of layers of
mapping files. Each layer is added to the next to form a complete map. Most
cities now have a GIS department that oversees the collection and currency
of the data. GIS, when teamed up with a GPS, makes it possible to navigate
to an airport or direct to a house number.
The advantage of GIS data is twofold. First, GIS data is
accurate. The entire city’s planning department is using the same database,
and it is accurate to amazing levels. For example, water lines are one layer
and sewer lines are another. Roads, alleys, parks and hydrology all get
their own layer, and the list goes on. Each layer of information can be
switched on or off as required for a particular job. For moving maps,
hydrology is used to show all of the waterways, roads of all sizes and
parcel data to show the actual parcel of land a house sits on. As you zoom
in, more detailed data is displayed.
Second, GIS data is current. By the time a cartographer
produces a paper map and it is printed and distributed, it is frequently a
year out of date. GIS is being used daily by the city’s planning department,
so there is frequently a road in the map before there is a road on the
ground. This means you are flying with the latest information possible. New
subdivisions are already in your system before the construction is underway.
GIS and digital data have opened up an amazing list of
possibilities to aid the law enforcement professional in giving more
information when directing ground crews. For example, you can couple
databases together like "repeat offenders" and "threat level," so you can
inform the ground crews that a known weapons offender lives at the target
address. Underwater features can be displayed so you know if a boat is
fishing illegally, or distance from shorelines can be added to aid offshore
operations.
You can now have power line layers that tell you there
are power lines on the north side of the road crossing the intersection, and
that there is a cell phone tower a quarter of a mile west on the north side
as well.
Data from a number of sensors can be displayed on a
tactical mapping system simultaneously. Live TFRs, real-time weather, TIS,
ADS-B, TCAD, search patterns, radio direction finder data for locating theft
recovery systems, ELTs and PLBs and other RF sources can all be placed on a
moving map in real-time.
When combined with an air data, attitude, heading and
reference system, several mapping systems are capable of locking a gimbal on
a target and keeping it there regardless of where the aircraft maneuvers.
High-end systems with a custom database can provide ownership and contact
information for an address simply by pointing the cross hairs of the gimbal
at the address in question.
Even though aircrews become familiar with their area of
operations, modern GPS based moving map systems can help reduce response
time. And it has been demonstrated that a quick response time can
dramatically increase arrest rates. For crimes where flight from the scene
is a major risk, for example, decreasing the response time from 4 to 2
minutes increases the arrest rate 100 percent, according to calculations by
the Toronto Police Service.
When using GPS data with a mapping system, you must
remember that some of the data being displayed is based on what has already
taken place. Speed calculations are based on the distance traveled between
two points and the time it took to travel that distance. When an aircraft is
turning, the entire mapping system is being updated based on information
that has been collected in the past. Even though the data may only be
milliseconds old, there could be a discrepancy between where the aircraft is
now and where the mapping system thinks it is. The error will vary with the
speed of the GPS samples and the speed of the computer driving the system.
Tight turns magnify the error.
Flight departments can use an "open architecture"
computer running Windows to load programs specifically for their operation.
There are units running weight and balance software, word processors for
safety briefings and mobile dispatch terminals (MDTs), to name a few. In
that case, the MDT software runs on Windows as well, so addresses can be
copied and pasted from the MDT software into the mapping software to save
time and reduce spelling errors. Having a mobile dispatch terminal in the
helicopter allows the crew to self dispatch to a call, rather than hearing
about the breaking and entering in progress 10 minutes after the call comes
in.
Another benefit to an open architecture system is the
ability to save a flight, or a portion of a flight, to the computer. You can
then download it to a CD or a USB jump drive and take it into the office to
review and debrief a flight or incident.
Hardware is also an important part of today’s moving
maps. Backlit keyboards are common, but of more importance is the actual
computer. Some manufacturers have proprietary hardware that does only the
moving map job, and nothing else.
Others employ a hardened, ruggedized computer that can
withstand the helicopter’s harsh environment. Experiments with a tough
laptop computer showed that it could be dropped from a ladder all day long
with no ill effects, but it lasted only three nights in the helicopter.
Using a tablet PC provides the ability to take a system
from one aircraft to another. Screen size and brightness are limited with a
tablet, but the cost of acquisition is often lower than an aircraft-mounted
system.
When selecting a screen size for a tablet or mounted
system, the screen is measured on a diagonal from corner to corner. The
larger the screen, the easier it is going to be when it comes to reading
street names.
Display brightness is typically measured in NITs or cd/m2.
To give you a comparison, the monitor you are using for an office computer
may have brightness in the range of 250 NITs or 250 cd/m2. If taken outside
when the sun is out, it would not be usable. LCD screen manufacturers
typically say that 400 NIT is readable in the sunlight.
If night vision goggles (NVGs) are going to be used,
there are several companies capable of making the conversion. Most if not
all screens, including tablets, can be converted for NVG use.
Computer hardware can come with or without DO160
environmental testing. The DO160 standard is an environmental standard for
vibration, temperature, mold growth, water tightness and other environmental
conditions. It is not a measure of service life for equipment.
For more information, the
ALEA online buyer’s
guide contains a list of the affiliate members that provide moving map
systems. A good moving map system will help you do a better, safer job.
Lon Arnold is the Director of marketing and business development for Becker
Avionics, Inc. He holds Commercial Multi-Engine, Instrument certificates.
Greg Taylor is president of Flight Management Systems, a company
manufacturing digital moving mapping systems since 1999.
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What’s All The Noise About?
By Michael J. Grady
Vice President Power Sonix
The use of public address (PA) systems, or loudhailers,
from helicopters is on the rise. A technology that once was cumbersome and
mostly a novelty is today valued by some right alongside searchlights and
cameras./p>
Charles Banks and Harry Brown pioneered the development
of loudhailers for use on aircraft in the early 1950s. Together they formed
a company named Applied Electro Mechanics in Alexandria, Virginia. Brown
developed a high-powered, small-sized, lightweight, germanium transistor
amplifier that proved to be very effective in projecting intelligible speech
over distances greater than a mile. Their motto was, "If you can see them,
talk to them." Their first application was to install their amplifier and
speakers on a fixed-wing aircraft to warn away small boats on the Saint
Lawrence Seaway from the path of the ship carrying the Queen of England on
her first visit to Canada. Since that time, many advances in technology and
utilization have been developed for loudhailer systems.
Many may recall their dramatic use in "Apocalypse Now,"
depicting a loudhailer playing Wagner’s "Flight of the Valkyries" to
terrorize their enemy. But since the September 11 disaster, the use of
loudhailers to communicate life saving information has become less of a
novelty and more of a necessity. Many are now realizing that the best way to
impart critical information during an emergency, in real time, is the use of
powerful, mobile loudhailers that cover wide areas and can be understood
over the rotor noise of the aircraft. Loudhailers can be extremely
beneficial warning systems, not only for terrorist attacks, but also for
other life threatening natural phenomena such as tornados or flash floods.
Indonesians have begun to use helicopter-mounted loudhailers for the
quickest possible warning response to oncoming tsunamis. Further, they also
can be used effectively for crowd control at large public events where the
need to communicate with everyone at once is imperative.
Richard Parrella, of the San Diego Police Air Support
Unit, reports that loudhailers are especially important in their law
enforcement efforts. Working with George Sparling of American Eurocopter,
the San Diego Police were able to get FAA approved, recessed-mounted
loudhailer systems on recently purchased A-Star 350s. While some users mount
the units on strut supports, others prefer the more aesthetic appearance of
a recessed mount; both types can be effective for loudhailer broadcast.
Parrella reports that the main use of PA systems by the
unit is to help in locating criminal suspects and missing persons. During a
daytime search, people at home will call police if they are made aware of
the possible presence of a hiding suspect. By broadcasting the suspect’s
description, citizens will report someone hiding from police on their
property. This same strategy also works in locating missing juvenile,
elderly, senile or disabled persons. Parrella also says that lifeguards
estimated that there were 600,000 people on the San Diego Beach on the
Fourth of July, and they used their PA systems to help with found/missing
children and to disperse large crowd gatherings.
"The San Diego Air Support Unit believes that their
public address system is such a valuable tool, they include its potential
uses in their lecture given to new recruits at the Police Academy." Parrella
said.
Other applications of loudhailers on helicopters include
their use by pilots flying for the U.S. Border Patrol, especially in desert
areas. PA systems can be used to quickly warn those on the ground fighting
forest fires when winds suddenly change direction, or to warn civilians out
of harms way when collecting or dropping water from airborne water bombers.
They can be used by beach patrols to warn swimmers of dangerous currents or
shark threats. Many cities are now experiencing problems associated with the
gathering of large bird flocks. Using loudhailer sirens, helicopter pilots
can drive this nuisance out of the city and into rural areas. Helicopters
have even used high intensity loudhailers for the early triggering of
avalanches, before the snow gets to deep, avoiding danger to homes and
skiers.
There are a multitude of factors to consider once the
need for a loudhailer on a helicopter is determined. Some of the more
important criteria include aircraft power requirements (watts), sound
pressure level (SPL) required for a given range (dB), physical size and
weight, cost, means of control (cockpit control or hand held remote) and
mounting methods (recessed or external). A general rule of thumb is that, on
a typical airborne law enforcement helicopter, 300 watts of power will
project your voice .75 miles, and a 600 watt system will project it 1.0
mile.
Sound measurements are not linear, they are logarithmic,
which means doubling the power will not double your distance. To double the
distance, you need four times the power. But for most applications in law
enforcement, the 300-600 watt range of power has proven very effective. The
exception would be for a helicopter like a Black Hawk, for which one would
use a minimum of 1,200 watts to overcome the loud rotor noise.
Typical horns, or bells, are not highly directional. This
means that your loudhailer does not have to be pointed right at your target
to get your message across. This is important when the person you wish to
communicate with is moving and not easily pinpointed.
When mounting the speaker horns, they are usually
positioned at an angle of 30 - 45 degrees down from the horizontal. At 45
degrees, the best speech projection toward your target is at a distance away
(measured from a point on the ground directly under you to the target) that
is equal to your altitude. For example, if you were at an altitude of 1,000
feet, your best projection would be to a target 1,000 feet away as measured
from underneath you on the ground to the target.
Ideally, the user would like a system that is small in
weight and size, has high electrical efficiency – such as a class D
amplifier (95 efficient) – has excellent intelligibility (e.g. it is not
only loud but understandable) and is easy to mount and control.
There are not many companies that specialize in the
manufacture of airborne loudhailer systems. Power Sonix of Martinsburg, West
Virginia, and Northern Airborne Technology (NAT) of Canada are the two most
prominent in the Northern Hemisphere. Both of these companies make
controllers for loudhailers, as well as the devices themselves, in a variety
of size and power configurations. NAT manufactures cockpit controllers used
with loudhailers, as well as separate power amplifiers and speaker arrays.
Likewise, Power Sonix manufactures separate speakers and amps, as well as
amplified speakers – systems in which an externally mounted horn array has
the amplifier built into the speaker chassis for reduced size, weight and
cabling.
When considering the mounting of loudhailers, the
end-user generally contracts with a helicopter completion center for help in
mounting their chosen system. Because there are so many types of
helicopters, loudhailer manufacturers typically don’t try to provide mounts
for varied installations. It is customary for the helicopter manufacturer to
recommend a completion center if they are not already using one for their
customers.
Scott Davis of Dallas Avionics, a distributor of cutting
edge avionics equipment, sees a future in which loudhailers, searchlights
and cameras will each be mounted under the aircraft in separate aerodynamic
pods that track together using a single controller for optimal utilization
and the complementary effectiveness of all three technologies. One thing
seems clear: the potential use of loudhailers on helicopters has not been
exhausted. The limits of loudhailer use are bound only by the imaginations
and needs of the pilots themselves as they define their respective missions.
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BEYOND the RADAR
Advancements in Weather Monitoring
by Jim Alviani
Director of Aviation Services, Meterologix
Although there are lots of free weather services on the
Internet, they’re not necessarily something you’d want to use to make
operational fight decisions. The quality and reliability of data varies
significantly. Fortunately, the FAA has established the Qualified Internet
Content Provider (QICP) certification to ensure a minimum level of
reliability.br>
Advancements in technology are taking weather briefings to a new level and
providing pilots and dispatchers with more information and better
situational awareness than ever before to help make mission-critical
decisions. Good weather information is also useful for ground operations to
alert you of potentially hazardous conditions that could affect valuable
assets.
Real-time radar information is a must. But not all radar
is the same. Some radar imagery is just raw data passed on from the National
Weather Service (NWS) NEXRAD sites that haven’t been filtered to remove
false echoes. And some radar is low resolution and only updated every 15
minutes, so it doesn’t give you an accurate picture of what’s really going
on.
But high quality radar imagery is available. Some weather
providers use a staff of meteorologists along with proprietary algorithms to
control quality and enhance the data. High resolution (1km) imagery, updated
every five minutes, is displayed in 16 colors that designate the intensity
and type of precipitation (snow, ice or rain).
Weather attributes for each storm cell also can be
displayed to advise you of echo tops, wind velocity, potential for hail and
the anticipated storm path. Sophisticated computer models can also project
the radar imagery up to 90 minutes into the future, so you can determine
where and when the storm will impact you.
New mapping software enables various weather layers and
map layers to be overlaid on a single graphic, so you don’t have to look at
multiple charts. Individual layers can be turned on or off to customize the
chart to your specific preferences. Your base location or other reference
points can be plotted on the map, and a range ring or distance tool can give
you added perspective. Thousands of weather observation points are available
to help give you a better picture of weather conditions when flying to
remote locations that aren’t near an airport.
To save time and make briefings quick and easy, some
systems provide the capability to select your most frequently viewed charts
and store them in a folder so you don’t have to navigate through the entire
system to find what you want. There’s also a screen with quadrants that
display multiple graphics at the same time so you can monitor a location
without having to toggle back and forth.
Automated weather alerts can be generated based on
user-defined thresholds and sent to appropriate personnel via email, cell
phone or pager. Alerts for lightning can be important for ground crew so
they can stop fueling operations, and alerts for approaching hail or high
winds can prompt precautionary steps to protect or move aircraft.
When responding to a HAZMAT situation where potentially
hazardous airborne material is involved, you can get an instant snapshot of
the plume dispersion based on real-time weather information, overlaid on a
street-level map that highlights the nearest schools and hospitals. Minutes
count and emergency personnel approaching the scene from the wrong direction
can be fatal, so a detailed graphic can be very helpful when coordinating
the movement of first responders or directing evacuation activities.
Weather systems also can now be integrated with
Geographic Information System (GIS) mapping software to create a very
powerful and highly sophisticated decision support system. Current and
forecasted weather information is converted into geo-referenced data layers
that can be combined with many other map layers or data layers. The GIS
application continuously monitors multiple weather parameters against
geographic assets and automatically triggers location-specific alerts when
critical thresholds are exceeded. This "weather-enabled" GIS decision
support system allows businesses and organizations to monitor specific
weather threats and manage their weather-related risks in ways never-before
possible.
Technology changes almost as fast as weather does. And
good technology is like good weather – it makes everything better.
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