Air Beat Magazine: September - October 2006

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September - October 2006

Legal Aspects of Forward-Looking Infrared Technology
Understanding Probable Cause

The Next Generation of Airborne Imaging Technology
Seeing Is Believing

Microwave Downlinks For Airborne Law Enforcement

Throw Away The Paper
The Evolution of Moving Map Technology

What’s All The Noise About?

BEYOND the RADAR 
Advancements in Weather Monitoring

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. 
  


   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.


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."


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 APSA 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.
 


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.


  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.