Introduction to How Thermal Imaging Works

 

In the aftermath of the Boston Marathon bombings, the manhunt to end all manhunts was underway. There was just one problem -- in spite of their massive advantage in manpower and firepower, authorities couldn't seem to find the perpetrators.
Tipped off by a suspicious homeowner, they finally narrowed their search to a large, covered boat sitting in a driveway. Because the suspect was hidden from sight, they couldn't visually confirm his exact position in the boat, nor could they see whether he was armed. Officers were working in the dark, blind to danger. That's when a thermographic camera helped save the day.
That camera, mounted to a helicopter circling overhead, clearly showed the man lying prone on the floor of the boat. It also revealed that the person was alive and moving. Aided by the visual information from the helicopter, a SWAT team was finally able to approach the boat and apprehend the suspect.
A thermographic camera (or infrared camera) detects infrared light (or heat) invisible to the human eye. That characteristic makes these cameras incredibly useful for all sorts of applications, including security, surveillance and military uses, in which bad guys are tracked in dark, smoky, foggy or dusty environs ... or even when they're hidden behind a boat cover.
Archaeologists deploy infrared cameras on excavation sites. Engineers use them to find structural deficiencies. Doctors and medical technicians can pinpoint and diagnosis problems within the human body. Firefighters peer into the heart of fires. Utility workers detect potential problems on the power grid or find leaks in water or gas lines. Astronomers use infrared technology to explore the depths of space. Scientists use them for a broad range of experimental purposes.
There are different types of thermal imaging devices for all of these tasks, but each camera relies on the same set of principles in order to function. On the next page we'll pull off the blinders on exactly how thermal imaging works.

An illustration of the infrared portion of the electromagnetic spectrum.

2011 HowStuffWorks

Light Enlightenment

Human eyes are wonderfully complicated and intricate organs. They're made for seeing visible light. This light reflects off of objects, making them visible to us.
Light, which is a type of radiation, comes in more flavors than just the visible kind. The range of light spans an entire electromagnetic spectrum, comprised of visible and invisible light, as well as X-rays, gamma rays, radio waves, microwaves and ultraviolet light.
Wavelength (also called frequency) is what makes each of these types of light different from one another. At one end of the spectrum, for example, we have gamma rays, which have very short wavelengths. On the flip side of the spectrum, we have radio waves, which have much longer wavelengths. In between those two extremes, there's a narrow band of visible light, and near that band is where infrared wavelengths exist, in frequencies from 430 THz (tetrahertz) to 300 GHz (gigahertz).
By understanding infrared, we can use thermal imaging devices to detect the heat signature of just about any object. Nearly all matter emits at least a little bit of heat, even very cold objects like ice. That's because unless that object is at absolute zero (minus 459.67 degrees Fahrenheit or minus 273.15 degrees Celsius), its atoms are still wiggling and jiving, bumping around and generating heat.
Sometimes, objects are so hot that they put off visible light -- think about the red, blazing-hot coils on an electric stove or the coals in a campfire. At a lower temperature those objects won't glow red, but if you can definitely put your hand near them you can feel the heat, or infrared rays, as they flow outward towards your skin.
However, quite often our skin isn't very useful for detecting infrared. If you filled one cup with warm water and one with cool and set them on a table across a room, you'd have no idea which was which. A thermal imaging camera, however, knows instantly.
In a situation like this, humans rely on electronic tools for assistance. In essence, thermal imaging devices are a like a sidekick for our eyesight, extending our visual range so that we can see infrared in addition to visible light. Empowered with this expanded visual information, we become the superheroes of the electromagnetic spectrum.
But how can a digital device possibly pick up on invisible heat signals and create an image that makes sense to our eyes? On the next page you'll see how advances in digital processing make it possible.

Sir William Herschel, the astronomer who discovered infrared wavelengths. He’s also credited with discovering the planet Uranus.

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Thermal Imaging Heats Up

Thermographic cameras are high-tech, modern-day devices. But the discovery of infrared light came a long, long time ago.
In 1800, a British astronomer named Sir William Herschel discovered infrared. He did so by using a prism to split a ray of sunlight into its different wavelengths and then holding a thermometer near each color of light. He realized that the thermometer detected heat even where there was no visible light -- in other words, in the wavelengths where infrared exists.
Throughout the 1800's, a series of intrepid thinkers experimented with materials that changed in conductivity when exposed to heat. This led to the development of extremely sensitive thermometers, called bolometers, which could detect minute differences in heat from a distance.
Yet it wasn't until after World War II that infrared research really started heating up. Rapid advances took place, in large part thanks to the discovery of transistors, which improved the construction of electronics in a multitude of ways.
These days, the evolution of infrared cameras has diverged into two categories, called direct detection and thermal detection.
Direct detection imagers are either photoconductive or photovoltaic. Photoconductive cameras employ components that change in electrical resistance when struck by photons of a specific wavelength. Photovoltaic materials, on the other hand, are also sensitive to photons, but instead of changing resistance, they change in voltage. Both photoconductive and photovoltaic cameras both require intense cooling systems in order to make them useful for photon detection.
By sealing the imager's case and cryogenically cooling its electronics, engineers reduce the chance of interference and greatly extend the detector's sensitivity and overall range. These kinds of cameras are pricey, more prone to failure and expensive to fix. Most imagers don't have integrated cooling systems. That makes them somewhat less precise than their cooled counterparts, but also much less costly.
Thermal detection technology, however, is often integrated into tools called microbolometers. They don't detect photons. Instead, they pick up on temperature differences by sensing thermal radiation from a distant object.
As microbolometers absorb thermal energy, their detector sensors rise in temperature, which in turn alters the electrical resistance of the sensor material. A processor can interpret these changes in resistance and use the data points to generate an image on a display. These arrays don't need any crazy cooling systems. That means they can be integrated into smaller devices, such as night vision goggles, weapons sights and handheld thermal imaging cameras.

Thermal Imaging Intricacies

Thermal images work a little like the human eye. Only instead of picking up on visible, reflected light, thermal imaging devices detect the heat released by an object.
As you already know, objects both hot and cold emit heat. As that heat moves outward from the object, a thermal imaging device can see it. Like a camera, these devices have an optical lens, which focuses the energy onto an infrared detector. This detector has thousands of data points so that it can detect subtle changes in temperature, from about minus 4 degrees Fahrenheit (minus 20 degrees Celsius) to 3,600 degrees Fahrenheit (2,000 degrees Celsius).
Then, the detector constructs a thermogram, which is basically a temperature pattern. The data from the thermogram is transformed into electrical signals and zipped to a processing chip in the camera. That chip converts the thermogram's raw data into visual signals that appear on a display screen. The whole process works very quickly, updating about 30 times per second.
Many imagers show objects as monochrome pictures, with hotter areas shown as black and cooler areas as gray or white. On a color imager, hot objects jump off the screen as white, yellow, red and orange, while cool areas are blue or violet. These are called false color images, because the device artificially assigns colors to each area of the image -- unlike a regular camera, which creates true color images that show objects as they appear in real life.
Depending on the relative warmth of each object in view, the resulting image may offer striking visual detail, such as a full picture of a man holding a gun. In instances where temperature gradations are less distinct, the image may be fuzzier and less definitive.
Picture quality changes depending on whether the imager is active or passive. Active systems actually warm the surface of a target object using a laser or other energy source in order to make it more visible to its detector (and also anyone standing near the target area). For example, some car manufacturers warm vehicle parts as they pass through the factory, making any flaws in construction more visible to thermal cameras. Passive systems just detect the heat that the object emits naturally. Both systems have their pros and cons, but the simplicity of passive systems makes them far more common.

Don’t be confused. Night vision imaging (pictured here) is not the same as thermal imaging.

©JEREMY LEMPIN/AFP/Getty Images

Night Vision ... Nope

Early versions of infrared detectors were big, unwieldy and noisy. Contemporary cooled systems are much improved, but even now they are still heavy, bulky and expensive, and often attached to large vehicles or planes so that they can be moved to a location and then put to use.
One popular cooled system, for example, is the FLIR SAFIRE III, which was used to narrow the search for the Boston bombing suspect [source: Peluso]. This unit is tough enough for military use and stabilized with an onboard gyroscope, and it works on land vehicles or on aircraft. It also weighs 100 pounds and costs around $500,000 as of 2013. "Cheaper" detecting units often run into tens of thousands of dollars, making them too expensive for the general public.
Uncooled products are much less expensive, and they are a lot smaller, too. Take the Extech i5 -- it costs around $1,600 and it weighs the same as a can of soda. It has a rechargeable lithium-ion battery, a 2.8-inch (7.1-centimeter) color LCD screen and, like a typical digital camera, it stores its pictures to a removable flash card.
Or consider the FLIR Scout PS24 monocular, which retails for roughly $2,000. It's only 6.7 inches (17 centimeters) long, so hikers, hunters and security professionals can take it wherever they roam. In spite of its small size, it has a color display and is waterproof, too.
Some of these imagers offer nifty features such as picture-in-picture displays, interchangeable lenses, laser pointers (so you can see exactly where you're pointing the camera), integrated GPS, WiFi connectivity and even microphones so that you can add voice comments to each image.
The Extech and FLIR products are both based on microbolometer technology. They're much different than most of the night-vision or infrared illuminated cameras common at the consumer level. You know these gadgets -- they produce that sickly green glow in movies and TV shows.
That kind of night vision doesn't detect heat. Instead, those products greatly amplify wisps of ambient light in order to reveal objects in the dark. In other words, they still need visible light being reflected off of those objects or they won't work very well.
The same goes for infrared illuminated cameras. These cameras project an infrared beam (think of your TV's remote control), which bounces off target objects and reflects light back towards the camera sensor.

In May 2009, the Budapest Airport used a a thermographic camera at a security gate to monitor passenger temperatures to screen for possible carriers of influenza A(H1N1).

©ATTILA KISBENEDEK/AFP/Getty Images

Super-hot Tech

Thermal imagers are continually improving in sensitivity and features. But they are not a perfect technology.
Sure, these cameras can see heat signatures within vehicles, homes and other dense materials. But any physical material (such as glass windows) that blocks heat will reduce the device's effectiveness. You can even buy clothing that will counter some heat seeking sensors [source: Maly].
There's also the matter of interpreting the images that appear on a camera's display. The often fuzzy, changeable pictures are simply representations of temperature and not actual pictures, so making sense of them depends on the user's expertise. Inexperienced people may misinterpret those images, especially in scenarios with extenuating circumstances such as inclement weather or interference.
Expense will continue to be an issue for anyone without deep pockets. Even the most affordable imagers cost many hundreds of dollars, and they have only a fraction of the capability of those deployed by government and military agencies.
Those that have the dough, though, can perform some amazing feats. The security and surveillance aspects are almost a given -- bad guys have a lot fewer places to hide when cops and soldiers can track suspects even without visual line of sight, whether it's in an urban area, on national borders or inside buildings.
Using thermal cameras, fire fighters can locate people trapped inside structures, home in on hot spots and pinpoint structural problems before someone gets hurt. Scientists can find Arctic polar bear dens deep within snow banks. Ancient ruins often exhibit different heat signatures than the soil and rocks surrounding them, meaning archaeologists can use imagers to find their next excavation site.
Building inspectors carry thermal cameras to find leaks or deficiencies in roofs and insulation. Similarly, remediation workers can find water and subsequent mold growth behind walls, even in cases where a property owner had no idea there was a problem.
Power grid components that are overheating may lead to failure and then blackouts. To ward off outages, workers leverage imagers to spot deteriorating areas in a grid. Gas leaks are another major challenge for utilities, and thermal cameras can see leaks before they become bigger issues.
Worried about an epidemic? Install thermal cameras at high-traffic public areas like rail stations and airports and you can spot feverish folks in a crowd.
The list of uses goes on and on. And as companies invest more in research and development, thermal cameras will only get better and cheaper, and thus find a place in many more situations, from recreation to research. What's now a hot technology is only getting hotter, and we humans are seeing our world in a whole new way.

Lots More Information

Author's Note: How Thermal Imaging Works

We call them thermal cameras, but they aren't really cameras. Instead, thermal imagers are sensors. And for the moment, they are really, really pricey. I was fortunate enough to play with a handheld imager a few years ago when we were searching for the source of a mysterious water intrusion in a suburban home. Camera in hand, we found that one corner of the house was much cooler than other walls. We removed the drywall and found a hole just big enough to create a water problem during heavy downpours. We may have used the device for only a couple of hours, but it definitely proved its worth.

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Sources

• Atherton, Kelsey D. "How it Works: The Thermal Camera that Found the Boston Bomber." Popular Science. April 25, 2013. (May 3, 2013) http://www.popsci.com/technology/article/2013-04/how-works-awesome-thermal-camera-found-boston-bomber
• Beckhusen, Robert. "DARPA Finally Shrinks Massive Thermal Cameras into Handheld Devices." Wired. April 17, 2013. (May 3, 2013) http://www.wired.com/dangerroom/2013/04/darpa-infrared-cameras/
• Boyle, Alan. "Secret Weapon? How Thermal Imaging Helped Catch Bomb Suspect." NBC News. April 20, 2013. (May 3, 2013) http://usnews.nbcnews.com/_news/2013/04/19/17830076-secret-weapon-how-thermal-imaging-helped-catch-bomb-suspect?lite
• Brown, Emily and Leinwand, Donna. "Helicopter, Infrared Cameras Help Confirm Suspect in Boat." USA Today. April 20, 2013. (May 3, 2013) http://www.usatoday.com/story/news/nation/2013/04/20/boston-suspect-boat-helicopter-infrared/2099959/
• Electronic Design. "Infrared Sensors – The All-Purpose Detection Devices." May 7, 2009. (May 3, 2013) http://electronicdesign.com/energy/infrared-sensors-all-purpose-detection-devices
• European Space Agency. "Caroline and William Herschel: Revealing the Invisible." (May 3, 2013) http://www.esa.int/Our_Activities/Space_Science/Herschel/Caroline_and_William_Herschel_Revealing_the_invisible
• Dalesio, Emery P. "Thermal Imaging a Hot New Archaeology Tool." Los Angeles Times. May, 14, 2000. (May 3, 2013) http://articles.latimes.com/2000/may/14/news/mn-29896
• Davis, Joshua. "The Fire Rebels." Wired. June 2005. (May 3, 2013) http://www.wired.com/wired/archive/13.06/firefight.html
• Drank, Nadia. "Infrared Images Reveal Frigid, Purple Penguins." Wired. March 5, 2013. (May 3, 2013) http://www.wired.com/wiredscience/2013/03/infrared-penguins/
• FLIR product page. "Star SAFIRE III." 2011. (May 3, 2013) http://gs.flir.com/uploads/file/products/brochures/star_safire_III_a_ltr.pdf
• FLIR Corporate Page. "Why Use Thermal Imaging?" (May 3, 2013) http://www.flir.com/cs/emea/en/view/?id=41530
• FLIR Corporate Page. "What's the Difference Between Thermal Imaging and Night Vision?" (May 3, 2013) http://www.flir.com/cvs/americas/en/view/?id=30052
• Homeland Security News Wire. "FLIR Shows New Thermal Imaging Camera." May 3, 2007. (May 3, 2013) http://www.homelandsecuritynewswire.com/flir-shows-new-thermal-imaging-camera
• IEC Infrared Systems. "Infrared Cameras: How They Work." (May 3, 2013).
• http://www.iecinfrared.com/how-infrared-cameras-work.html
• Infrared Security Solutions product page. "LongView." (May 3, 2013) http://www.iss-thermal.com/longview.html
• Kondas, David A. "Introduction to Lead Salt Infrared Detectors." U.S. Army Armament Research, Development and Engineering Center. Feb. 1993. (May 3, 2013) http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA260781&Location=U2&doc=GetTRDoc.pdf
• Parks, Bob. "Tool: Hot Shot Thermal Imager for Law Enforcement." Wired. Oct. 6, 2009. (May 3, 2013) http://www.wired.com/magazine/2009/10/st_tool_thermal_imager/
• Rogalski, Antoni. "History of Infrared Detectors." 2012. (May 3, 2013) http://antonirogalski.com/wp-content/uploads/2012/12/History-of-infrared-detectors.pdf
• Texas Instruments history page. "Defense." (May 3, 2013) http://www.ti.com/corp/docs/company/history/lowbandwidthtimelinedefense.shtml
• White, Jack R. "Herschel and the Puzzle of Infrared." American Scientist. May-June 2012. (May 3, 2013) http://www.americanscientist.org/issues/feature/2012/3/herschel-and-the-puzzle-of-infrared

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10 Games That Take Minutes to Learn and a Lifetime to Master

Nolan Bushnell, the video game pioneer who invented Pong in the early 1970s, explained the game's runaway popularity by noting that it was "very simple to learn, difficult to master" [source: Singleton]. But Bushnell's theorem, as that principle came to be known in the electronic entertainment industry, actually was no more than a reflection of wisdom that predates our gadgetry by thousands of years.
In an ancient Assyrian carving now in the British Museum, for example, palace guards are shown passing the time by playing the Game of Twenty Squares, invented in the city of Ur in southern Iraq about 4,600 years ago [source: BBC]. That same game is still played today, as are scores of others in which humans toss dice, shuffle cards, and move pieces around boards in pursuit of what might seem to be the simplest of objectives -- but which, if one's opponent is sufficiently skilled and wily, often turn out to be maddeningly difficult.
That seeming paradox is what makes classic games, from chess and checkers to the Asian game of Go, so perennially appealing. As author Jesse Schell explains in his book "The Art of Game Design," such games have what he terms "emergent complexity," in that their simple rules allow players the flexibility to create a multitude of intricate scenarios. At the same time, these games also incorporate small, measured amounts of what Schell calls "innate complexity" -- that is, subtle restrictions that make them more difficult.
Here are 10 prime examples of these seemingly simple, yet delightfully complex, games.

10: Go

There's a legend that, instead of fighting an invading army, an ancient Buddhist ruler of Tibet avoided bloodshed by challenging the leader to a game of Go. Whether or not that actually happened, Go, which may have originated in China, has been a popular pastime in Asia for some 3,000 years.
At first glance, the game appears beguilingly simple. Two players -- one equipped with white stones, the other with black ones -- sit down at opposite sides of a board consisting of a basic 19-line-by-19-line grid, and take turns placing stones on the vacant intersection points. A player wins by claiming more intersections than his or her opponent and /or by surrounding and capturing more of the opponent's pieces than the opponent takes.
The tension between those two different ways of scoring, and the seemingly endless strategic and tactical options that arise, are what makes the game so appealing. While it looks easy to play, in practice, Go is so challenging that, so far, no one has been able to program a computer to play the game more skillfully than the best human masters [source: International Go Federation].

Backgammon may seem like a game of luck, but enthusiasts will tell you differently.

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9: Backgammon

Backgammon is one of the world's oldest games. Archaeologists discovered a board and pieces beneath the rubble of the ancient Burnt City in Iran's Sistan-Baluchistan province, which dates back to 3000 B.C. [source: Payvand Iran News]. It also was played by the Romans, who called it Ludus Duodecim Scriptorum ("the 12-sided game"). And it became a popular diversion among American college students in the 1970s.
Backgammon's appeal, in part, lies in its symmetrical minimalism -- two players, each armed with 15 pieces called stones -- try to move them in opposite directions around a board divided into quadrants, along a path of 24 points connected by lines, and then remove them all from the board. The number of points a player can move a stone is determined by the roll of the dice, which gives backgammon the appearance of being a game of luck. In truth, chance determines the outcome only when two players are of identical levels of ability, according to the enthusiasts' Web site Backgammon.org, which offers an extensive library of articles on backgammon tactics and strategy. The ability to perform mathematical calculations in one's head and analyze the impact of various options is one thing that separates the best players from dabblers [source: Simborg].

8: Shogi

In the West, Shogi is sometimes called "Japanese chess." It was invented around the same time -- the oldest known pieces were found in a temple built in Horyuji in the 7th century A.D. But it developed separately from the version of chess that became popular in Europe.
There are some obvious similarities between the two games. Shogi and chess both have the same basic object -- to checkmate the enemy's king -- and they both are played on boards that are grids of alternating squares, with rows of pieces that symbolize medieval armies (though the Japanese game denotes the pieces with written characters, rather than carvings of figures). And both games are played by young schoolchildren and adults alike in elite competitions.
But that's pretty much where the similarities end. Shogi's rules are very different from Western chess and are designed to allow opportunities for a player who seems to be losing to reverse his or her fortune. After taking an enemy piece, for example, a player can add it to his or her army and place it on any space on the board. (Ownership of a piece is denoted by the direction in which it is facing.) Additionally, pieces can receive battlefield promotions once they reach certain squares, which gives them additional abilities. As gaming author Jack Botermans notes, "You can never be sure you are actually winning until you capture the enemy king" [source: Botermans].

A domino set was found in the tomb of an Egyptian pharaoh.

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7: Dominoes

The origins of the domino -- a small, flat, rectangular block of wood or bone, with one blank side and the other usually marked by an arrangement of spots, called pips -- is a bit murky. The oldest known domino set, found in the tomb of the Egyptian pharaoh Tutankhamen, dates back to 1355 B.C., and the medieval Chinese apparently played dominoes, as well, before they showed up in Europe sometime in the mid-1700s [source: Armanino].
Today, European and American domino sets generally have 28 pieces, each marked with a different configuration of pips, such as 6-5, 4-0 or 3-1. They're used to play a variety of different games -- for example, Muggins, the most popular American game. Two to four players are involved. The dominoes are shuffled facedown on the table, and players draw for the lead, with the "heaviest" piece -- that is, the one with the most pips -- winning the chance to go first. Each player than randomly draws the number of pieces required for the game (in American games, usually seven). The lead player then lays down a piece, usually the one with the most pips. The other player or players have the opportunity to match it with a similarly valued piece, or to pass. The laying down of pieces continues until someone plays all of his or her pieces; the winner gets a number of points equivalent to the pips on the pieces remaining in the other players' possession. The first player to 50 or 100 wins.
While most casual players probably assume that the outcome of a dominoes game is mostly the luck of the draw, hard-core dominoes enthusiasts develop complex strategies, based on intricate mathematical computations that they perform in their heads, which dictate when to play pieces with various pip counts [source: Yates].

6: Charades

What could be simpler than a game that requires no equipment, except for a set of limbs, facial muscles, and a mouth, tongue and vocal cords for shouting out guesses? Charades is a game in which one player wordlessly pantomimes a word or phrase drawn from a hat -- often the title of a book or movie -- for teammates to try to guess.
The origins of charades are a bit obscure; the name may come from the Italian word schiarare, which means "to disentangle," or schiarato, which translates as "clear" or "unraveled" [source: Cantab]. But by the late 1800s, it had become a popular pastime among affluent ladies' luncheon groups and gatherings of male artists and intellectuals alike. An 1896 dispatch published in The New York Times bemusedly describes a club of young male intellectuals in Chicago who staged regular public events, in which they pantomimed current events suggested to them by members of the audience [source: The New York Times].
But while the rules of charades are relatively simple -- basically, you can't speak what you are trying to convey, or use gestures to spell it out -- the game can be devilishly difficult, if it's played by competitors who delight in filling the hat with exceedingly complex or obscure words or phrases, or ones that are too abstract to portray visually with ease.

There are just 16 regulations in tournament level checkers play.

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5: Checkers

Like dominoes, checkers -- also known as draughts -- dates back at least several thousand years to Egypt, where archaeologists have found familiar-looking round pieces and boards marked with grids of squares in ancient tombs [source: Walker]. In 360 B.C., the Greek philosopher Plato also mentioned the game in his book "The Republic." He asks, "But is the just man or the skillful player a more useful and better partner in the game of draughts?" [source: Plato]. The game survived the decline of the Hellenic world, and eventually resurfaced in Renaissance Europe, where the first checkers rule manual was published in 1549.
Today, there are different versions of the game, including Standard American checkers, which is the one played in the United States. In the American game, players face off on either side of a 64-square board, each armed with 12 pieces. The game's object is to capture all of the opposing player's pieces by jumping over them, or to leave him or her with no legal moves. Initially, a piece can only move forward diagonally, until it reaches the row closest to the opponent, which is known as the "king's row." At that point, a piece is "crowned," and can move either forward or backward [source: American Checker Federation].
Rules-wise, checkers is so simple that even U.S. tournament-level completion has just 16 relatively terse regulations. But that's deceiving because elite players use tactics and strategies with names such as "the double-ended trapping trio trick" and the "forced capture policy" that rival chess masterminds' gambits in complexity [source: Checkers-strategy.com].

4: Reversi /Othello

The origins of this board game are enveloped in murky Victorian-era miasma. By some accounts, Reversi was invented in 1870 by an Englishman named J.W. Mollett, who originally called it the Game of Annexation [source: Wood]. But another Englishman, Lewis Waterman, claimed to have invented the game as well. In 1887, he registered the name "Reversi" as a trademark, and then obtained a court injunction against Mollett's publisher, F.H. Ayres. Ultimately, Waterman lost his case, when an appeals court decided that the name, which apparently was borrowed from an earlier French card game, was not a "fancy" (i.e., original) word under British law, and thus could not be trademarked [source: Law Times]. To make things ever more confusing, in 1971, a Japanese salesman named Goro Hasegawa invented a similar but not quite identical game, Othello, named after a Shakespearian character that undergoes a dramatic reversal of fortune [source: Time, Associated Press].
Fortunately, compared to its tangled history, the basic game concept is much more straightforward. It's played on a grid with 64 spaces, exactly the same number as the total pieces (each player gets 32). Once the game starts, the players take turns adding pieces to the board, with the restriction that they can only place them on squares that are adjacent to one of their opponent's pieces, and there can only be one piece on each square. In addition, a player can only place a piece on the board after capturing an opponent's piece, by trapping it between two of his or her own pieces. Captured pieces can change sides multiple times during the game as well [source: Botermans]. That simple-yet-complex format allows skilled players to develop elaborate gambits, such as simultaneous multiple captures, and makes the game a favorite among brainy college math and science whizzes.

Parcheesi is the American version of this board game.

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3: Pachisi

In the Indian game of Pachisi, two to four players move pieces known as pawns around a cruciform board and reach their home square, or charkoni. The game dates back to approximately the 6th century A.D. and is closely related to another Indian game, chaupar. The name is the Hindi and Urdu word for 25, which is the highest number that players originally could roll with the cowrie shells that they once used as dice [source: Botermans].
The 16th-century emperor Akbar was a fanatical devotee of the game. When Akbar built a new capital for himself at Fatehpur Sikri, he included a giant stone board, on which he played marathon games lasting as long as three months, using slave girls dressed in colorful costumes as live pieces [source: Abram]. A century or so later, English travelers brought the game back from India to Europe. The game's concept was so appealing that it inspired clones such as the English game Ludo and Americanized versions such as Parcheesi, which was first copyrighted by E.G. Selchow and Co. in 1869, and is now made by Hasbro [source: University of Waterloo].
On a superficial level, pachisi seems simple to play, but skilled players use complex tactics and strategy, such as using pawns to erect barriers for opponents and capturing an opponent's pawns, forcing them to start over. Another factor that adds complexity is that in the four-person game, players form partnerships. Even after a player's pawns have reached the charkoni, he or she will continue to assist the partner, running pawns on additional laps and teaming up to form barriers for the other two players [source: Botermans].

2: Scrabble

In Scrabble, one of the most popular board games of all time, players use tiles with letters on them to spell out words on a grid, crossword-puzzle style. The idea is so clear and simple that you'd think some sage would have dreamed it up in antiquity. But in fact, the game originated in the 1930s, when an unemployed architect named Alfred Mosher Butts passed the time by creating a new word game.
Butts' inspiration was to combine the vocabulary skills required for crossword puzzles and anagrams with the additional element of chance. The methodical inventor studied the front page of The New York Times, and tabulated how often each of the alphabet's 26 letters were used. (Among other things, he discovered that vowels appear far more often than consonants, and that the vowel "E" was the most frequently used of all.) Based upon letters' frequency, he assigned different point values to them, concocted some simple rules, and then used his architectural drafting equipment to draw a board for a game that he initially called Lexico and then Criss-Cross Words, before he took on a partner, entrepreneur James Brunot, who helped him come up with a catchier moniker, Scrabble [source: Hasbro].
The game's enduring appeal is that while its concept is easy to understand, it's challenging to play because coming up with word combinations from a random assortment of letter tiles requires both intellectual agility and a big vocabulary. According to a 2004 New York Times article on the Scrabble subculture, the game's elite -- the 100 or so top tournament players -- have working vocabularies in excess of 120,000 words, which is three to four times that of the typical college graduate. As one top player noted in the article: "You can't really compete at the top level without knowing every word between two and nine letters" [source: Smith].

Chess challenges both the young and the old.

Brand X Pictures/Thinkstock

1: Chess

Chess, a stylized simulation of warfare that probably first originated in India in the 7th century A.D., may be the most universally popular board game ever created -- and one of the most addictive. As David Shenk recounts in his 2007 book "The Immortal Game," the French painter Marcel Duchamp, one of the most influential figures in 20th-century modern art, gradually became such an obsessive chess player that by his early thirties, he had virtually stopped producing art, so that he could devote virtually every waking minute to playing. "Everything around me takes the shape of the knight or the queen, and the exterior world has no other interest for me other than its transformation to winning or losing positions," he wrote [source: Shenk].
Chess has been an object of fascination and obsession for so many over the years because it embodies Bushnell's theorem; on the most basic level, it's so simple that elementary-school children can learn its rules, such as the diagonal-only movement of bishops and the king's ability to move only one square at a time. At the same time, that simple structure gives virtuosos the ability to conceive and perform complex strategies. While chess is often thought of as a mathematical game, experts say the real contest is often a psychological one, in which players scrutinize one another for subtle cues and tendencies that predict behavior and reveal weaknesses. As Soviet chess trainer Mark Dvoretsky once noted: "The opponent makes an apparently innocent move, but for some reason or another, he rouses our vigilance and promptly we discover the cunning that is concealed" [source: Avni].

http://entertainment.howstuffworks.com/leisure/brain-games/10-games-minutes-to-learn-lifetime-to-master.htm/printable

Система оплаты проезда общественного транспорта Москвы

Предыстория В далёком 2005 году, когда я был ещё мелким ребёнком, я впервые увидел такую вещь как «Социальная карта москвича» Смотря на то как пенсионеры прикладывают её при проходе через турникеты наземного транспорта и метрополитена, я стал задумываться над тем, как же работает вся эта система. Но в детстве у меня не было возможности этим заняться. Позже, когда я уже сам начал зарабатывать деньги, я решил всерьёз приступить к изучению системы оплаты проезда в общественном транспорте.

RFID
Конечно же я начал с поиска в гугле и без особых усилий нашёл название данной — RFID (Radio Frequency IDentification) или в переводе на русский Радиочастотная Идентификация. Прочитав статью на википедии, я понял что метки (карты) делятся на 3 диапазона работы, Метки диапазона LF (125—134 кГц), Метки диапазона HF (13,56 МГц), Метки диапазона UHF (860—960 МГц). В общественном транспорте используются метки второго диапазона — HF.

Карты
Сами же карты выпускаются под именем торговой марки Mifare, которая объединяет несколько типов микросхем смарткарт, микросхемы считывателей и продукты на их основе.
На данный момент производятся 5 видов микросхем для карт:

Mifare Classic 1k, Mifare Classic 4k
Mifare Ultralight
Mifare Ultralight C
Mifare Plus
Mifare DESFire EV1

В нашем общественном транспорте используются первый и второй виды карт.

Социальная карта москвича сделана на основе Mifare 1k
Социальная карта студента сделана на основе Mifare 4k
Билет на несколько поездок на метрополитене сделан на основе Mifare Ultralight
1k и 4k означают объём памяти на карте 1 и 4 килобайт соответственно.
Так же у меня в наличии была социальная карта жителя московской области, которая отличалась от первой только названием и дизайном.


Практика
Естественно чтобы посмотреть данные записанные на карте и как то с ними поработать нужен был ридер для этих карт. В процессе поиска я наткнулся на модель под названием ACR122U. По цене он меня вполне устраивал, с доставкой с интернет-аукциона ebay вышло около 60 долларов.
Вот наконец 3 недели спустя я получил заветную посылку, в ней лежал сам ридер, две пустые белые карты Mifare 1k и диск с драйверами и дистрибутивом.

Собственно ридер.

Я сразу же подключил его к ноутбуку, установил нужные драйвера, ридер определял карту, всё шло как надо. Теперь же у меня возник вопрос о том, как считать свою карту. Изначально я думал, что на диске будут все необходимые для этого программы и это будет проще простого, но оказалось не тут то было. Из того что было на диске, полезными, как бы это смешно не звучало, оказались только драйвера. Пришлось снова воспользоваться поиском.

Софт
После нескольких дней поиска я нашёл такой комплект средств разработки под названием libNFC. Немного изучив его я понял, что это именно то, что нужно. Одновременно с этим я наткнулся на блог одного человека по имени Александр darksimpson Симонов, который рассказывал о системе работы турникетов метрополитена, а также о данном проекте. Более того, он даже собрал все необходимые программы под винду, что было весьма удобно. Дальше я приступил к испытаниям. Но для начала расскажу о структуре карты.

Структура карты
Здесь я рассмотрю структуру карт Mifare 1k и 4k. Карта 1k разделена на 16 секторов, от 0 до 15. Нулевой сектор, это блок производителя, в котором записан индивидуальный серийный номер карты UID он прописывается на производстве и не поддаётся изменению. Остальные 15 секторов доступны для считывания/записи. Каждый сектор имеет два ключа вида A и B, а также LOCK-биты.
Комбинация последних даёт считывающему устройству информацию о том, разрешена ли запись/чтение и то с помощью какого вида ключей это можно сделать. В основном считывание происходит через ключи вида А, запись через ключи вида B. На пустых картах во всех секторах стоят ключи FFFFFFFFFFFF.Для 4k ситуация аналогичная, но вместо 16 секторов на ней 40. То есть чтобы считать содержимое карты на компьютер нужно знать ключи от всех 16 секторов, но так как на всех проездных билетах все ключи изменены, возникает логичный вопрос, как же узнать эти ключи? В этом мне помогла утилита MFCUK доработанная и собранная под винду другим блоггером под никнеймом Odinokij_kot. О работе этой программы вы можете прочитать в его статье

Пример работы MFCUK

Считывание карты
Для считывания карты мне понадобилась скачанная программа mfclassic_d.exe, найденные ключи для моей социальной карты жителя московской области и командная строка. В последней я указал путь к программе, файл с ключами от моей карты, вид ключей, запрос на считывание и имя файла в который запишется дамп карты. После нажатия заветной кнопки Enter пошёл процесс считывания, через пару секунд всё закончилось, о чем свидетельствовала надпись Done, 64 of 64 blocks read. Writing data to file: card.mfd… Done. После этого я попытался разобраться в тех данных, которые были записаны на карте, но меня это ни к чему не привело, так как в файле была лишь куча шестнадцатиричных чисел, единственное более менее понятными оказались паспортные данные записанные в одном из секторов. Запись карты производится аналогично, только нужно указать файл с ключами для той карты на которую мы записываем.

Пример работы mfclassic_d

Начало экспериментов. Тест номер №1
Сначала я считал карту до прохода через турникет автобуса, и после. Тоже самое я сделал с турникетом в метро. После сравнения дампов карты, я выяснил, что после прохода в автобусах, трамваях и троллейбусах изменяются только данные записанные в 4 секторе, остальные данные оставались теми же, в метрополитене менялись только данные 1 сектора. Отсюда вывод, метрошники используют 1 сектор, наземники 4.

Тест №2. Наземка
Вторым вопросом стояла возможность клонирования моей карты на одну из двух белых, которые шли в комплекте к ридеру. Указав в программе файл моей карты, а также ключи от пустой карты я начал процесс записи, времени ушло немного больше чем при считывании, примерно 4 секунды. В окне командной строки появилась надпись Done, 64 of 64 blocks written, что свидетельствовало об успешной записи на карту. После этого я отправился на Боевое крещение. Подошёл автобус, на остановке было 3 человека, я заходил последним, чтобы не создать очередь в случае непредвиденной ситуации. Итак, я подхожу к турникету, прикладываю только что записанную карточку, и о чудо, турникет показал срок действия моей социальной карты, заморгал зелёной лампой и дружелюбно пропустил меня в салон. Моему счастью не было предела. Позже я проверил карту на троллейбусах и трамваях, результат был тем же.

Тест №3. Метрополитен
Воодушевлённый успехами на наземном транспорте, я отправился в метро. Спустившись, я подошел к турникету, приложил ту же самую белую карту, на мониторе турникета высветилась надпись Действителен до: чч.мм.гг, после чего я спокойно прошел через турникет. Для меня, конечно, результат был ожидаем, но нотки сомнения всё равно присутствовали. Я был доволен как слон, в моей голове была мысль о безоговорочной победе над общественным транспортом города Москвы. Заехав в одно место, примерно через час мне снова пришлось спуститься в метро и тут меня ждал самый большой сюрприз. Приложив белую карту к турникету я увидел зловещую надпись Билет не исправен. Я приложил её ещё к паре турникетов, результат был тем же. Тогда я достал настоящую социальную карту и лишь с её помощью успешно прошёл через турникет. В метро я продолжал думать что же всё таки произошло. Выйдя на улицу пошёл на остановку, сел на автобус, приложил белую карту, она сработала. Странно, подумал я. Вернувшись домой я стал выяснять что же не так. Не найдя никакого логического объяснения я лёг спать. Следующим утром я спустился в метро, приложил свою оригинальную социальную карту и увидел ту самую пресловутую надпись Билет не исправен. После чего я проследовал в кассу за получением объяснения происходящего, где мне сказали что «возможно вы передали карту другому человеку, который по ней прошёл и это заметили. Из-за этого вашу карту занесли в СТОП-лист» Потом мне объяснили что нужно делать и куда ехать чтобы карту разблокировали. Через 2 недели по моему заявлению карту разблокировали и я продолжал по ней ездить.


СТОП-лист
Об этом самом листе в интернете не так много информации, всё что я о нём знаю, я услышал от людей не понаслышке знающих эту систему. В него заносятся серийные номера карт (UID) тех карт, которые ведут себя не корректно, а также например номера студенческих карт, владельцы которых были отчислены из университета. Данный СТОП-лист хранится в каждом турникете в метро и синхронизируется с общей базой примерно каждые 10 минут. Если вы прикладываете карту, с UID занесенным в этот лист, то турникет вас не пропустит, пусть даже срок действия карты ещё не закончился. Теперь объяснение того почему заблокировали мои карты. После того как я приложил белую карту, турникет отправил данные в базу для проверки, где сопоставляется UID и остальная информация о карте, срок действия и её номер (не UID). В ходе проверки база выясняет, что на данный UID нету выданной карты, она ищет настоящий UID по этим данным и после этого отправляет оба UID в СТОП-лист. То есть карты заблокировали из-за того, что серийный номер белой картой отличался от оригинального. Почему такого не произошло на наземном транспорте? Да потому что у всех наземных турникетов не существует общей базы данных, в которой могли бы сопоставляться данные, её нету из-за того что невозможно соединить все турникеты воедино. Таким образом турникет считывает только тип карты и срок её действия, не обращая внимания на UID, который в свою очередь может быть любым.

MIfare Zero
Остановиться в своих экспериментах я не мог, а в размышлениях так тем более. И вот меня посетила мысль, что если вдруг как то изменить UID на такой же как и у оригинальной карты. И вот после поисков в гугле я наткнулся на блог ещё одного человека по имени Андрей, который писал о способе клонирования Mifare карт. Оказалось что существуют неофициально выпускаемые карты под названием Mifare Zero. В этих самых картах блок производителя то бишь UID можно изменить на любой другой. Пообщавшись с Андреем я выяснил, что у него имеются данные карты, и что для экспериментов он готов продать мне одну из них. Мы договорились о встрече на одной из станций метро, где я и обзавёлся этой картой.

Изображение Mifare Zero из блога Андрея

Эксперимент №5. Возвращение в метро
Записав свою карту на карту Mifare Zero, с помощью утилиты mfsetuid_d.exe я поставил на неё UID своей социальной карты. Теперь это были две идентичные карты, которые отличались лишь рисунком, на одной он был, на другой нет. Спустившись в метро я успешно прошёл по данной карте, но радоваться было рано, надо было через некоторое время повторить проход, чтобы точно удостовериться в работоспособности карты и том, что её не заблокируют. Целую неделю я проходил через турникет по белой карте, всё было отлично, в СТОП-лист её не вносили. Успех!

Эксперимент №6
Следующим что я захотел испытать получится ли осуществить проход сразу нескольких людей, потому как по моей карте можно было пройти 1 раз в 7 минут. Взяв обе карты, мы с другом пошли в метро. Сначала прошёл я по оригинальной карте, затем друг по белой на соседнем турникете, пока что всё отлично, посидев в макдаке, мы поехали обратно, но к сожалению обе карты оказались заблокированными. Объяснение этому в том, что после моего прохода в базу пришли данные о моей карте, они проверились, всё сходится, следом прошел друг и данные снова верны. Но система увидела то, что по одной карте прошли 2 раза не выдержав 7 минутный интервал, такого быть не может, карта ведет себя не корректно и поэтому система её заблокировала. Вывод из этого такой, клонировать карту всё таки можно, но система защиты в метрополитене работает отлично и обойти её всё-таки наверное невозможно. Но пара задумок всё ещё оставалась.

Эксперимент №7
Предметом этого испытания стали карты студента. Однажды я предположил что если к примеру есть два студенческих проездных. Один из них продлен на данный месяц, второй нет. Так вот, если банально скопировать 1 сектор с продлённого проездного на непродлённый, то может что и выйдет?.. Начало месяца. Я не стал продлевать студенческую карту и взял на несколько часов продленную карту своей подруги, считал содержимое 1 сектора и записал на свою карту. После этого я отправился в метро со своей картой, приложив её я увидел что срок действия карты до конца текущего месяца. В результате я в течении всего дня ездил по данной карте, её не блокировали. Тут я снова подумал теперь точно победа, карта на блокируется и продлевать её можно с любого продленного студенческого, но как обычно не тут то было. Следующим утром карта была заблокирована. Видимо это случается потому, что в конце каждого дня база проверяет был ли действительно данный студенческий билет продлён на текущий месяц, в нашем случае нет, следовательно карту в СТОП-лист

Выводы
Система осуществления оплаты проезда в московском метрополитене создана с точным знанием всех открытий в сфере Mifare. Нет, конечно можно пройти по неоригинальному билету, но сделать это вы сможете всего несколько раз, после чего её заблокируют. Система СТОП-листа работает на должном уровне. Как говорится «бесплатный сыр только в мышеловке».

В следующей статье я расскажу о своих экспериментах на наземном транспорте, с различными видами карт и типами проездных. Спасибо за внимание.

Данная статья написана только для ознакомления, и ни в коем случае не призывает заниматься подделкой проездных билетов, так как это противоречит статье 327 УК РФ. Автор не несет ответственности за любые неправомерные действия совершенные людьми, под воздействием данной статьи.

http://habrahabr.ru/post/175557/

Фундаментальные проблемы экономики на Bitcoin

Годится ли Bitcoin как основная валюта для полноценной экономики?



В этой статье я подчеркну несколько не для всех очевидных проблем, которые заложены в природе Bitcoin. А также предложу вам вместе со мной подумать и порассуждать о возможных альтернативах.

Проблемы

Bitcoin имеет дефляционную природу. Создатель валюты заложил в неё это алгоритмически, при создании. Посудите сами: валюта имеет чётко заданный и строго падающий со временем объём эмиссии. При этом рынок заведомо растёт, а значит растут объёмы торговли и растёт потребность в валюте. То есть, фактически, ограниченная эмиссия заведомо не удовлетворяет потребность рынка в валюте. Как следствие — стоимость валюты всё время растёт, то есть, наблюдается дефляция.

В чём главная проблема экономики, основанной на дефляционной валюте? Стагнация. Грубо говоря, постоянно растущий курс валюты побуждает людей не тратить деньги, а накапливать их. Кроме того, возможность получать прибыль от простого накопительства избавляет людей от необходимости производить товары и услуги. В результате получается жёсткий кризис всей экономики, потому что общество не может жить в достатке, когда никто ничего не делает.

Вторая важная проблема — это спекулятивность рынка. Когда курс валюты по природе своей вынужден постоянно расти, неизбежны пузыри. Классический сценарий:



Bitcoin же по своей дефляционной природе обречён постоянно повторять такие пузыри раз за разом. Например, за последние два года можно наблюдать два очень похожих пузыря: лето 2011 и весна 2013. Уровни при этом отличались в 10 раз, а пропорции аналогичные. Такие пузыри почти невозможно сдерживать: когда валюта постоянно растёт, даже медленно, она интересует спекулянтов. Купил дёшево, подождал пол-года, продал дорого. И чем больше таких энтуизастов, тем сильнее подстёгивается рост. Это неизбежно вызывает экспоненциальный рост валюты, пузырь. При таком пузыре мы наблюдаем приблизительно 20-кратный рост курса, за которым следует обрушение. И ведь рынок после обрушения не умирает: биткоины реально используются, например на том же постоянно растущем Silk Road, и для других продаж, участники которых желают анонимности и неподконтрольности. Получается, что такая картина пузыря неизбежно будет повторяться раз за разом, с определённой периодичностью. То есть, стабильного курса мы не дождёмся никогда, он всегда будет скакать в разы и даже в десятки раз. Какая при этом экономика может быть построена?

У Bitcoin появилось много форков, предлагающих альтернативные схемы. Но все они схожи в одном — в своей дефляционной природе. Потому что все они созданы для спекуляций прежде всего.

Что делать?

Я приглашаю всех подумать над тем, как построить реальную экономику, основанную на анонимной децентрализованной валюте. Такую экономику, которую не будет «лихорадить», бросая то в жар, то в холод, из-за пузырей на главной валюте. Возможно, необходима определённая замена Bitcoin, с другими алгоритмами эмиссии? Или не замена, а дополнение?

Мои соображения на счёт альтернативной валюты

В чём заключается важная роль государства в экономике страны? Регуляция экономики, стимуляция её роста, сглаживание кризисов. Для этого, в частности, государство обладает монопольным правом эмиссии основной валюты. Этим инструментом можно пользоваться так, чтобы страна процветала. Но при этом все вынуждены доверять право эмиссии некоему узкому кругу лиц, которых никто не знает лично. Со всеми вытекающими проблемами и постоянным желанием всё переделать на новый лад (а на самом деле, на старый, но с новыми людьми).

Но можно же заложить механизм автоматической регуляции эмиссии алгоритмически в саму валюту. При этом схема может быть очень простой, например: если объёмы рынка растут, снижаем эмиссию; объёмы падают — увеличиваем эмиссию. По аналогии с автоматической регуляцией сложности майнинга, позволяющей более-менее точно придерживаться чётко заданного объёма эмиссии. Такой регуляцией можно добиться более-менее стабильной стоимости валюты, которая позволит экономике развиваться гораздо более полноценно.

Но есть и проблема у такого подхода. Как внедрить в обществе валюту, чья цена не растёт как на дрожжах? Обратите внимание на пики роста популярности Bitcoin: они случаются совершенно отчётливо на почве бешеного роста курса. Будем честными: основная масса людей, наполняющих рынок и задающих ему всё растущую популярность, движима жаждой наживы. Очень узка прослойка людей, использующих Bitcoin по назначению — для анонимных неконтролируемых денежных переводов. И захотят ли эти люди переходить на новый незнакомый инструмент со сложным непонятным механизмом эмиссии только ради теоретической стабильности его курса? Большой вопрос.

Хочу услышать ваши соображения и предложения на этот счёт. Давайте вместе порассуждаем. Построить экономику пусть не идеальную, но гораздо лучше нынешней, — возможно. Нужно только придумать, как.

http://habrahabr.ru/post/181356/

How RFID Works

Introduction to How RFID Works

Long checkout lines at the grocery store are one of the biggest complaints about the shopping experience. Soon, these lines could disappear when the ubiquitous Universal Product Code (UPC) bar code is replaced by smart labels, also called radio frequency identification (RFID) tags. RFID tags are intelligent bar codes that can talk to a networked system to track every product that you put in your shopping cart.
Imagine going to the grocery store, filling up your cart and walking right out the door. No longer will you have to wait as someone rings up each item in your cart one at a time. Instead, these RFID tags will communicate with an electronic reader that will detect every item in the cart and ring each up almost instantly. The reader will be connected to a large network that will send information on your products to the retailer and product manufacturers. Your bank will then be notified and the amount of the bill will be deducted from your account. No lines, no waiting.
RFID tags, a technology once limited to tracking cattle, are tracking consumer products worldwide. Many manufacturers use the tags to track the location of each product they make from the time it's made until it's pulled off the shelf and tossed in a shopping cart.
Outside the realm of retail merchandise, RFID tags are tracking vehicles, airline passengers, Alzheimer's patients and pets. Soon, they may even track your preference for chunky or creamy peanut butter. Some critics say RFID technology is becoming too much a part of our lives -- that is, if we're even aware of all the parts of our lives that it affects.
In this article, you'll learn about the types of RFID tags and how these tags can be tracked through the entire supply chain. We'll also look at the noncommercial uses of RFID tags and how the Departments of State and Homeland Security are using them. Lastly, we'll examine what some critics consider an Orwellian application of RFID tags in animals, humans and our society.

Launch Video

Spytek Shorts: Surveillance Bugs

Bar codes like this one are found on almost every product we purchase.

©iStockphoto.com/essxboy

Reinventing the Bar Code

Almost everything that you buy from retailers has a UPC bar code printed on it. These bar codes help manufacturers and retailers keep track of inventory. They also give valuable ­information about the quantity of products being bought and, to some extent, the consumers buying them. These codes serve as product fingerprints made of machine-readable parallel bars that store binary code.
Created in the early 1970s to speed up the check out process, bar codes have a few disadvantages:

• In order to keep up with inventories, companies must scan each bar code on every box of a particular product.
• Going through the checkout line involves the same process of scanning each bar code on each item.
• Bar code is a read-only technology, meaning that it cannot send out any information.

RFID tags are an improvement over bar codes because the tags have read and write capabilities. Data stored on RFID tags can be changed, updated and locked. Some stores that have begun using RFID tags have found that the technology offers a better way to track merchandise for stocking and marketing purposes. Through RFID tags, stores can see how quickly the products leave the shelves and which shoppers are buying them.
RFID tags won't entirely replace bar codes in the near future -- far too many retail outlets currently use UPC scanners in billions of transactions every year. But as time goes on we'll definitely see more products tagged with RFIDs and an increased focus on seamless wireless transactions like that rosy instant checkout picture painted in the introduction. In fact, the world is already moving toward using RFID technology in payments through special credit cards and smart phones -- we'll get into that later.
In addition to retail merchandise, RFID tags have also been added to transportation devices like highway toll passcards and subway passes. Because of their ability to store data so efficiently, RFID tags can tabulate the cost of tolls and fares and deduct the cost electronically from the amount of money that the user places on the card. Rather than waiting to pay a toll at a tollbooth or shelling out coins at a token counter, passengers use RFID chip-embedded passes like debit cards.
But would you entrust your medical history to an RFID tag? How about your home address or your baby's safety? Let's look at two types of RFID tags and how they store and transmit data before we move past grocery store purchase­s to human lives.

RFID tags like these used to be made only for tracking luggage and large parcels.

Thinkstock/Hemera/Thinkstock

RFID Tags Past and Present

RFID technology has been around since 1970, but until recently, it has been too expensive to use on a large scale. Originally, RFID tags were used to track large items, like cows, railroad cars and airline luggage, that were shipped over long distances. These original tags, called inductively coupled RFID tags, were complex systems of metal coils, antennae and glass.
Inductively coupled RFID tags were powered by a magnetic field generated by the RFID reader. Electrical current has an electrical component and a magnetic component -- it is electromagnetic. Because of this, you can create a magnetic field with electricity, and you can create electrical current with a magnetic field. The name "inductively coupled" comes from this process -- the magnetic field inducts a current in the wire. You can learn more in How Electromagnets Work.
Capacitively coupled tags were created next in an attempt to lower the technology's cost. These were meant to be disposable tags that could be applied to less expensive merchandise and made as universal as bar codes. Capacitively coupled tags used conductive carbon ink instead of metal coils to transmit data. The ink was printed on paper labels and scanned by readers. Motorola's BiStatix RFID tags were the frontrunners in this technology. They used a silicon chip that was only 3millimeters wide and stored 96 bits of information. This technology didn't catch on with retailers, and BiStatix was shut down in 2001 [source: RFID Journal].
Newer innovations in the RFID industry include active, semi-active and passive RFID tags. These tags can store up to 2 kilobytes of data and are composed of a microchip, antenna and, in the case of active and semi-passive tags, a battery. The tag's components are enclosed within plastic, silicon or sometimes glass.
At a basic level, each tag works in the same way:

• Data­ stored within an RFID tag's microchip waits to be read.
• The tag's antenna receives electromagnetic energy from an RFID reader's antenna.
• Using power from its internal battery or power harvested from the reader's electromagnetic field, the tag sends radio waves back to the reader.
• The reader picks up the tag's radio waves and interprets the frequencies as meaningful data.

Inductively coupled and capacitively coupled RFID tags aren't used as commonly today because they are expensive and bulky. In the next section, we'll learn more about active, semi-passive and passive RFID tags.

Active, Semi-passive and Passive RFID Tags

Active, semi-passive and passive RFID tags are making RFID technology more accessible and prominent in our world. These tags are less expensive to produce, and they can be made small enough to fit on almost any product.
Active and semi-passive RFID tags use internal batteries to power their circuits. An active tag also uses its battery to broadcast radio waves to a reader, whereas a semi-passive tag relies on the reader to supply its power for broadcasting. Because these tags contain more hardware than passive RFID tags, they are more expensive. Active and semi-passive tags are reserved for costly items that are read over greater distances -- they broadcast high frequencies from 850 to 950 MHz that can be read 100 feet (30.5 meters) or more away. If it is necessary to read the tags from even farther away, additional batteries can boost a tag's range to over 300 feet (100 meters) [source: RFID Journal].
Like other wireless devices, RFID tags broadcast over a portion of the electromagnetic spectrum. The exact frequency is variable and can be chosen to avoid interference with other electronics or among RFID tags and readers in the form of tag interference or reader interference. RFID systems can use a cellular system called Time Division Multiple Access (TDMA) to make sure the wireless communication is handled properly [source: RFID Journal].
Passive RFID tags rely entirely on the reader as their power source. These tags are read up to 20 feet (six meters) away, and they have lower production costs, meaning that they can be applied to less expensive merchandise. These tags are manufactured to be disposable, along with the disposable consumer goods on which they are placed. Whereas a railway car would have an active RFID tag, a bottle of shampoo would have a passive tag.
Another factor that influences the cost of RFID tags is data storage. There are three storage types: read-write, read-only and WORM (write once, read many). A read-write tag's data can be added to or overwritten. Read-only tags cannot be added to or overwritten -- they contain only the data that is stored in them when they were made. WORM tags can have additional data (like another serial number) added once, but they cannot be overwritten.
Most pass­ive RFID tags cost between seven and 20 cents U.S. each [source: RFID Journal]. Active and semi-passive tags are more expensive, and RFID manufacturers typically do not quote prices for these tags without first determining their range, ­storage type and quantity. The RFID industry's goal is to get the cost of a passive RFID tag down to five cents each once more merchandisers adopt it.
In the next section, we'll learn how this technology could be used to create a global system of RFID tags that link to the Internet.

Talking Tags

When the RFID industry is able to lower the price of tags, it will lead to a ubiquitous network of smart packages that track every phase of the supply chain. Store ­shelves will be full of smart-labeled products that can be tracked from purchase to trash can. The shelves themselves will communicate wirelessly with the network. The tags will be just one component of this large product-tracking network.
The other two pieces to this network will be the readers that communicate with the tags and the Internet, which will provide communications lines for the network.
Let's look at a real-world scenario of this system:

• At the grocery store, you buy a carton of milk. The milk containers will have an RFID tag that stores the milk's expiration date and price. When you lift the milk from the shelf, the shelf may display the milk's specific expiration date, or the information could be wirelessly sent to your personal digital assistant or cell phone.
• As you exit the store, you pass through doors with an embedded tag reader. This reader tabulates the cost of all the items in your shopping cart and sends the grocery bill to your bank, which deducts the amount from your account. Product manufacturers know that you've bought their product, and the store's computers know exactly how many of each product need to be reordered.
• Once you get home, you put your milk in the refrigerator, which is also equipped with a tag reader. This smart refrigerator is capable of tracking all of the groceries stored in it. It can track the foods you use and how often you restock your refrigerator, and can let you know when that milk and other foods spoil.
• Products are also tracked when they are thrown into a trash can or recycle bin. At this point, your refrigerator could add milk to your grocery list, or you could program the fridge to order these items automatically.
• Based on the products you buy, your grocery store gets to know your unique preferences. Instead of receiving generic newsletters with weekly grocery specials, you might receive one created just for you. If you have two school-age children and a puppy, your grocery store can use customer-specific marketing by sending you coupons for items like juice boxes and dog food.

In order for this system to work, each product will be given a unique product number. MIT's Auto-ID Center is working on an Electronic Product Code (EPC) identifier that could replace the UPC. Every smart label could contain 96 bits of information, including the product manufacturer, product name and a 40-bit serial number. Using this system, a smart label would communicate with a network called the Object Naming Service. This database would retrieve information about a product and then direct information to the manufacturer's computers.
The information stored on the smart labels would be written in a Product Markup Language (PML), which is based on the eXtensible Markup Language (XML). PML would allow all computers to communicate with any computer system similar to the way that Web servers read Hyper Text Markup Language (HTML), the common language used to create Web pages.
We're not at this point yet, but RFID tags are more prominent in your life than you may realize. Wal-Mart and Best Buy are just two major merchandisers that use RFID tags for stocking and marketing purposes. Automated systems called intelligent software agents manage all the data coming in and going out from RFID tags and will carry out a specific course of action like sorting items [source: RFID Journal].
The United States retail market is on the cusp of embracing a major implementation of RFID technology through payment systems that use Near Field Communication. These are the credit cards of the future.

Chase's Blink technology uses an RFID chip embedded in the card to process transactions with the mere wave of the hand.

Thomas Cooper/Getty Images

Near Field Communication, Smart Phones and RFID

NFC technology is promising because it presents the next evolution of convenient payment with an added layer of security. Some credit cards have NFC chips embedded in them and can be tapped against NFC payment terminals instead of swiped, which eliminates the possibility that someone could skim your data via the magnetic strip. This same system works with cellular phones, too: read up on how cellular electronic payments work to dig into the technology.
Google is one company pushing NFC payments with Google Wallet. The application stores credit card information under multiple layers of security and allows for quick tap payments at NFC terminals. That means the technology's usefulness is limited by the number of NFC payment terminals available in retail locations and the number of phones that support the technology -- at launch, Google Wallet only works with the Android Nexus S smart phone.
So what does this have to do with RFID? Near Field Communication devices can read passive RFID tags and extract the information stored in them. This technology is being used in modern advertising. For example, picture a normal poster advertising a pair of jeans, the kind of paper you'd see plastered on a wall in a shopping mall. Advertisers can make "smart" posters with RFID tags that add a new level of interaction with customers. Tap an NFC phone against a "smart" poster equipped with an RFID tag, and you may get a 10 percent off coupon for those jeans at Macy's. Passive RFID tags are cheap enough to be used in promotional materials just to engage customers.
NFC and RFID technologies have huge futures ahead of them in the retail world, but security remains a common concern. Some critics find the idea of merchandisers tracking and recording purchases to be alarming. Retail isn't the only industry using RFID technology: In the next section, we'll learn how the government is putting RFID tags to use.­

The U.S. government's Real ID

From air traffic to road traffic, security is becoming a more pressing issue, and some people feel that they're being monitored more closely than ever before. Real ID, a program developed by the 9/11 Commission, is intended to improve the way that official identification is issued. While the Real ID has yet to be approved (and is being heatedly debated), the first proposed Real ID is the Real ID driver's license. DHS issued a notice of proposed rulemaking for the Real ID driver's license on March 1, 2007. The Real ID driver's license can be enhanced to give you easy border-crossing access to Canada, and beyond a standard driver's license, it also grants you access to federal facilities, federal aircraft and nuclear power plants [source: Department of Homeland Security]. States will choose whether or not to embed RFID chips in the Real ID driver's license in place of the current 2-D bar code.

Government-issued RFIDs

While many consumers happily -- or obliviously -- buy merchandise tracked with RFID tags, some people are up in arms about the U.S. government's legislation mandating that passports be embedded with RFID microchips.
On Aug. 14, 2006, the U.S. Department of State began issuing electronic passports, or e-passports. Prompted by the terrorist attacks of Sept.11, 2001 the Department of Homeland Security (DHS) proposed the e-passport as a security measure for air travel safety, border security and more efficient customs procedures at airports in the United States. The e-passport's enhanced security features -- a chip identification number, digital signature and photograph that acts as a biometric identifier -- make the passport impossible to forge.
The e-passport will help improve security, but with so much personal information embedded in the document, there have been many concerns raised about the e-passport's potential for identity theft. Two possible forms of identity theft that could occur with e-passports are:

• Skimming: when someone uses an RFID reader to scan data from an RFID chip without the e-passport holder's knowledge.
• Eavesdropping: when someone reads the frequencies emitted from the RFID chip as it is scanned by an official reader.

However, the DHS insists that the e-passport is perfectly safe to use and that proper precautions have been taken to ensure user confidentiality.

• For protection against skimming, the e-passport contains a metallic anti-skimming device. This device is a radio shield inserted between the passport's cover and first page. When the e-passport is closed, it can't be scanned at all; when it's open, it can only be read by a scanner that is less than 3.9 inches (10 centimeters) away [source: Department of State].

• To guard against eavesdropping, DHS has mandated that all areas where the e-passport is scanned be thoroughly covered and enclosed so that signals cannot be picked up beyond the authorized RFID reader.

The e-passport costs $97. While the cost may seem steep, the cost of installing RFID readers in airports is even more staggering. Adopting the e-passport will require gradual change, but aut­horities are already discussing what added security features and improved biometrics the next series of e-passports will have.
The debate over e-passports pales in comparison to debates over human chipping. Next, we'll learn what RFID microchips are doing in livi­ng things.

The Jacobs family of Boca Raton, Fla. served as early subjects for VeriChip implants. In 2002, Jeffrey, Leslie and their son Derek were chipped.

David Friedman/Getty Images

Animal and Human Chipping

Animal chipping is nothing new -- farmers have been tracking livestock for years using RFID technology. But companies are turning animal chipping for pets into big business, and some companies are offering options for human chipping.
RFID pet recovery systems rely on tiny microchips the size of a grain of rice that contains the pet owner's contact information and sometimes an animal's medical history. Veterinarians scan lost pets with an RFID reader to determine whether or not the pet has a microchip. But the system can break down here. There are many competing pet recovery systems and consequently, many pet microchips. The Humane Society of the United States has been campaigning for development of a universal RFID reader that vets could use to read a pet's microchip, no matter its manufacturer or year of manufacture. In November 2005, President George Bush signed a bill for the standardization of pet microchips and a national database of pet owner information [source: RFID Journal].
Even though the FDA approved the implantation of RFID microchips in animals and humans in 2004, research from as far back as 1996 shows that these implants can cause cancerous tumors in lab rats and mice [source: Washington Post]. Specifically, the implants caused sarcomas, which affect body tissue. No studies have proven yet that cancer can form in animals other than lab rats and mice, and it's still too early to tell what effects the chips can have on humans. No negative health effects have been linked to the radio waves emanating from RFID chips. Despite this evidence, or lack thereof, other disadvantages of human chipping may outweigh its advantages.
VeriChip Corp. is leading the human chipping business. The company makes microchips with unique identification numbers that link to a VeriChip medical database. The VeriChip database contains emergency contact information and medical histories. Patients with serious medical issues like Alzheimer's are ideal candidates for the VeriChip. In addition to a one-time implantation fee, VeriChip charges annual fees based on how much information you want in the database -- you can choose to have just your name and contact information or your full medical history. VeriChip is still growing, so there are not RFID readers in every hospital. Also, doctors might not scan every patient to check for a chip, so depending on the hospital or doctor, your VeriChip could prove useless.­
­­One VeriChip with greater rates of success is the Hugs Infant Protection Program. Under this RFID monitoring system, newborns in some hospital nurseries wear ankle bracelets with RFID chips. If an unauthorized person tries to remove a baby from the hospital, an alarm is sounded at the nurses' station and at exit doors. You can read more about successful infant abduction prevention on the VeriChip Web site.
In the next section, we'll hear what RFID critics have to say about tracking devices in our modern world.

RFID and SIDS

One researcher has developed an RFID system that monitors a baby's carbon dioxide levels in order to prevent sudden infant death syndrome (SIDS). Under this system, sensors attached to a crib sound an alert if they detect that the baby has stopped breathing, potentially saving young lives. Read more about this SIDS prevention system in the RFID Journal.­

Mandatory Human Chipping

In October 2007, California governor Arnold Schwarzenegger signed a bill making it unlawful for any employer to force an employee to be chipped. California is also working to ban RFID chips in REAL ID drivers' licenses [source: RFID Journal].

RFID Criticism

As with many new technologies, people fear what they don't understand. In the case of RFID, consumers have many fears, some of which may be justified. This debate may be one of the few in which you'll find the American Civil Liberties Union and Christian Coalition on the same side.
Human chipping has seemingly higher stakes than merchandise tagging, and RFID critics are concerned that human chipping may one day become mandatory. When the company CityWatcher.com chipped two of its employees in 2006, these fears spun out of control. CityWatcher.com insisted that the employees were not forced to be chipped -- they volunteered for the microchip implants for easier access to secured vaults where confidential documents are stored. Other employees declined the implants, and their positions with the company were unaffected.
­Aside from the limitations of VeriChip scanning discussed in the last section, human chipping has profound religious and civil liberty implications for some people. Some believe that human chipping is foretelling a biblical prophecy from the Book of Revelation, interpreting the chip as the "Mark of the Beast." To others concerned with civil liberties, the chip is bringing us one step closer to an Orwellian society, in which our every action and thought will be controlled by Big Brother.
While we can choose whether or not to put RFID chips in ourselves or our pets, we have little control over tags being placed on commercial products that we buy. In the book "Spychips: How Major Corporations and Government Plan to Track Your Every Move with RFID," Katherine Albrecht and Liz McIntyre describe the most extreme implications of RFID tags. They describe how RFID tags could be used to gauge your spending habits and bank account to determine how much you should be charged for the products you buy. This may sound paranoid, but hackers have proven that some RFID tags can be tampered with, including disabling their anti-theft features and changing the price that corresponds to their product. Better encryption is needed to ensure that hackers can't pick up RFID frequencies with super-sensitive antennae.
What's more, some critics say that relying on RFID as the primary means of security could make human security checkpoints lazy and ineffective. If security guards rely solely on the RFID anti-theft devices in merchandise and RFID technology of government-issued identification to screen for criminals or terrorists, they might miss the criminal activity happening right in front of their eyes.
To scan more information about RFID technology, blip to the links on the next page.­

Lots More Information

Related Arti­cles

• How UPC Bar Codes Work
• How Location Tracking Works
• How Pet Microchips Work
• How Anti-shoplifting Devices Work
• How Radio Works
• How Biometrics Works
• Are RFID ignition systems secure?

More Great Links

• Texas Instruments: Tag-It System
• RFID Journal
• Barcode Server
• Uniform Code Council
• Spychips

­­Sources

• Albrecht, Katherine and Liz McIntyre. "Spychips: How Major Corporations and Government Plan to Track Your Every Move with RFID." Chapter One. LFB.com. 2005 (10/17/2007). http://www.lfb.com/index.php?stocknumber=PV9017
• C.A.S.P.I.A.N. Consumers Against Supermarket Privacy Invasion and Numbering. (10/17/2007). http://www.nocards.org/
• "Chipped Passports Coming Monday." WIRED. 8/11/2006 (10/16/2007). http://www.wired.com/print.techbiz/media/news/2006/08/71583
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