Gyro-stabilized day/night binoculars manufactured by B.E. Meyers Company.
The first thing you probably think of when you see the words night vision is a spy or action movie you've seen, in which someone straps on a pair of night-vision goggles to find someone else in a dark building on a moonless night. And you may have wondered "Do those things really work? Can you actually see in the dark?"
The answer is most definitely yes. With the proper night-vision equipment, you can see a person standing over 200 yards (183 m) away on a moonless, cloudy night! Night vision can work in two very different ways, depending on the technology used.
Image enhancement - This works by collecting the tiny amounts of light, including the lower portion of the infrared light spectrum, that are present but may be imperceptible to our eyes, and amplifying it to the point that we can easily observe the image.
Thermal imaging - This technology operates by capturing the upper portion of the infrared light spectrum, which is emitted as heat by objects instead of simply reflected as light. Hotter objects, such as warm bodies, emit more of this light than cooler objects like trees or buildings.
Here, you will learn about the two major night-vision technologies. We'll also discuss the various types of night-vision equipment and applications. But first, let's talk about infrared light.
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 non-commercial 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.
Reinventing the Bar Code
Barcodes, like this one found on a soda can, are found on almost everything we buy.
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, by whom the products are being bought. 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 who's buying them.
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.
Bar Code History
At 8:01 a.m. on June 26, 1974, a customer at Marsh's supermarket in Troy, OH, made the first purchase of a product with a barcode, a 10-pack of Wrigley's Juicy Fruit Gum. This began a new era in retail that sped up checkout lines and gave companies a more efficient method for inventory control. That pack of gum took its place in American history and is currently on display at the Smithsonian Institution's National Museum of American History. That historical purchase was the culmination of nearly 30 years of research and development. The first system for automatic product coding was patented by Bernard Silver and Norman Woodland, both graduate students at the Drexel Institute of Technology (now Drexel University). They used a pattern of ink that glowed under ultraviolet light. This system was too expensive and the ink wasn't very stable. The system we use today was unveiled by IBM in 1973 and uses readers designed by NCR.
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.
This RFID tag from Texas Instruments dates back to 1999, when it was used to track luggage.
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 3mm 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 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]. Passive RFID tags rely entirely on the reader as their power source. These tags are read up to 20 feet 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.
This tiny RFID tag will be placed on a bottle of moisturizer.
Most passive RFID tags cost between 7 and 20 cents 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 5 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, 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. Some critics find the idea of merchandisers tracking and recording purchases to be alarming. But 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.
Government-issued RFIDs
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.
While many consumers happily -- or obliviously -- buy merchandise tracked with RFID tags, some people are up in arms about the federal government's legislation mandating that passports be embedded with RFID microchips.
On Aug. 14, 2006, the 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. 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 happens when someone uses an RFID reader to scan data from an RFID chip without the e-passport holder's knowledge.
Eavesdropping happens 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 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 Australian passport served as a model for the new United States e-passport.
The e-passport costs $97. While the cost to you 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.
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.
I Want You. . .To Chip Your Pets
On Sept. 26, 2006, the Secretary of the Navy mandated that all Navy and Marine Corps pet owners have their pets implanted with RFID chips [source: Secretary of the Navy]. This order came partly as a result of pet abandonment when some military families relocate and leave their pets behind.
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. 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 and 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.
The Jacobs family of Boca Raton, FL served as early subjects for VeriChip implants. In 2002, Jeffrey, Leslie and their son Derek were chipped.
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. 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.
RFID Criticism
George Orwell's "1984"
"1984" tells the story of a society in which all citizens are patrolled by the Thought Police, who ensure that no one has any independent or rebellious thoughts that aren't sanctioned by the Party. In this society, everyone answers to Big Brother -- the ultimate authority on education, government and recreation. When critics of RFID call the technology "Orwellian," they mean that the technology is too invasive and that businesses and government are made too knowledgeable of our private actions, just like Big Brother watching us.
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.
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].
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.
A GPS receiver uses satellites to pinpoint locations.
How GPS Receivers Work
Our ancestors had to go to pretty extreme measures to keep from getting lost. They erected monumental landmarks, laboriously drafted detailed maps and learned to read the stars in the night sky. Things are much, much easier today. For less than $100, you can get a pocket-sized gadget that will tell you exactly where you are on Earth at any moment. As long as you have a GPS receiver and a clear view of the sky, you'll never be lost again. In this article, we'll find out how these handy guides pull off this amazing trick. As we'll see, the Global Positioning System is vast, expensive and involves a lot of technical ingenuity, but the fundamental concepts at work are quite simple and intuitive. When people talk about "a GPS," they usually mean a GPS receiver. The Global Positioning System (GPS) is actually a constellation of 27 Earth-orbiting satellites(24 in operation and three extras in case one fails). The U.S. military developed and implemented this satellite network as a military navigation system, but soon opened it up to everybody else.
Each of these 3,000- to 4,000-pound solar-powered satellites circles the globe at about 12,000 miles (19,300 km), making two complete rotations every day. The orbits are arranged so that at any time, anywhere on Earth, there are at least four satellites "visible" in the sky. A GPS receiver's job is to locate four or more of these satellites, figure out the distance to each, and use this information to deduce its own location. This operation is based on a simple mathematical principle called trilateration. Trilateration in three-dimensional space can be a little tricky, so we'll start with an explanation of simple two-dimensional trilateration.
2-D Trilateration
Imagine you are somewhere in the United States and you are TOTALLY lost -- for whatever reason, you have absolutely no clue where you are. You find a friendly local and ask, "Where am I?" He says, "You are 625 miles from Boise, Idaho." This is a nice, hard fact, but it is not particularly useful by itself. You could be anywhere on a circle around Boise that has a radius of 625 miles, like this:
You ask somebody else where you are, and she says, "You are 690 miles from Minneapolis, Minnesota." Now you're getting somewhere. If you combine this information with the Boise information, you have two circles that intersect. You now know that you must be at one of these two intersection points, if you are 625 miles from Boise and 690 miles from Minneapolis.
If a third person tells you that you are 615 miles from Tucson, Arizona, you can eliminate one of the possibilities, because the third circle will only intersect with one of these points. You now know exactly where you are -- Denver, Colorado.
This same concept works in three-dimensional space, as well, but you're dealing with spheres instead of circles. Next, we'll look at this type of trilateration.
3-D Trilateration
Fundamentally, three-dimensional trilateration isn't much different from two-dimensional trilateration, but it's a little trickier to visualize. Imagine the radii from the previous examples going off in all directions. So instead of a series of circles, you get a series of spheres. If you know you are 10 miles from satellite A in the sky, you could be anywhere on the surface of a huge, imaginary sphere with a 10-mile radius. If you also know you are 15 miles from satellite B, you can overlap the first sphere with another, larger sphere. The spheres intersect in a perfect circle. If you know the distance to a third satellite, you get a third sphere, which intersects with this circle at two points. The Earth itself can act as a fourth sphere -- only one of the two possible points will actually be on the surface of the planet, so you can eliminate the one in space. Receivers generally look to four or more satellites, however, to improve accuracy and provide precise altitude information.
In order to make this simple calculation, then, the GPS receiver has to know two things:
The location of at least three satellites above you
The distance between you and each of those satellites
The GPS receiver figures both of these things out by analyzing high-frequency, low-power radio signals from the GPS satellites. Better units have multiple receivers, so they can pick up signals from several satellites simultaneously. Radio waves are electromagnetic energy, which means they travel at the speed of light (about 186,000 miles per second, 300,000 km per second in a vacuum). The receiver can figure out how far the signal has traveled by timing how long it took the signal to arrive
GPS Calculations
On the previous page, we saw that a GPS receiver calculates the distance to GPS satellites by timing a signal's journey from satellite to receiver. As it turns out, this is a fairly elaborate process. At a particular time (let's say midnight), the satellite begins transmitting a long, digital pattern called a pseudo-random code. The receiver begins running the same digital pattern also exactly at midnight. When the satellite's signal reaches the receiver, its transmission of the pattern will lag a bit behind the receiver's playing of the pattern.
A GPS satellite
The length of the delay is equal to the signal's travel time. The receiver multiplies this time by the speed of light to determine how far the signal traveled. Assuming the signal traveled in a straight line, this is the distance from receiver to satellite. In order to make this measurement, the receiver and satellite both need clocks that can be synchronized down to the nanosecond. To make a satellite positioning system using only synchronized clocks, you would need to have atomic clocks not only on all the satellites, but also in the receiver itself. But atomic clocks cost somewhere between $50,000 and $100,000, which makes them a just a bit too expensive for everyday consumer use. The Global Positioning System has a clever, effective solution to this problem. Every satellite contains an expensive atomic clock, but the receiver itself uses an ordinary quartz clock, which it constantly resets. In a nutshell, the receiver looks at incoming signals from four or more satellites and gauges its own inaccuracy. In other words, there is only one value for the "current time" that the receiver can use. The correct time value will cause all of the signals that the receiver is receiving to align at a single point in space. That time value is the time value held by the atomic clocks in all of the satellites. So the receiver sets its clock to that time value, and it then has the same time value that all the atomic clocks in all of the satellites have. The GPS receiver gets atomic clock accuracy "for free." When you measure the distance to four located satellites, you can draw four spheres that all intersect at one point. Three spheres will intersect even if your numbers are way off, but four spheres will not intersect at one point if you've measured incorrectly. Since the receiver makes all its distance measurements using its own built-in clock, the distances will all be proportionally incorrect. The receiver can easily calculate the necessary adjustment that will cause the four spheres to intersect at one point. Based on this, it resets its clock to be in sync with the satellite's atomic clock. The receiver does this constantly whenever it's on, which means it is nearly as accurate as the expensive atomic clocks in the satellites. In order for the distance information to be of any use, the receiver also has to know where the satellites actually are. This isn't particularly difficult because the satellites travel in very high and predictable orbits. The GPS receiver simply stores an almanac that tells it where every satellite should be at any given time. Things like the pull of the moon and the sun do change the satellites' orbits very slightly, but the Department of Defense constantly monitors their exact positions and transmits any adjustments to all GPS receivers as part of the satellites' signals.
Differential GPS
So far, we've learned how a GPS receiver calculates its position on earth based on the information it receives from four located satellites. This system works pretty well, but inaccuracies do pop up. For one thing, this method assumes the radio signals will make their way through the atmosphere at a consistent speed (the speed of light). In fact, the Earth's atmosphere slows the electromagnetic energy down somewhat, particularly as it goes through the ionosphere and troposphere. The delay varies depending on where you are on Earth, which means it's difficult to accurately factor this into the distance calculations. Problems can also occur when radio signals bounce off large objects, such as skyscrapers, giving a receiver the impression that a satellite is farther away than it actually is. On top of all that, satellites sometimes just send out bad almanac data, misreporting their own position. Differential GPS (DGPS) helps correct these errors. The basic idea is to gauge GPS inaccuracy at a stationary receiver station with a known location. Since the DGPS hardware at the station already knows its own position, it can easily calculate its receiver's inaccuracy. The station then broadcasts a radio signal to all DGPS-equipped receivers in the area, providing signal correction information for that area. In general, access to this correction information makes DGPS receivers much more accurate than ordinary receivers. The most essential function of a GPS receiver is to pick up the transmissions of at least four satellites and combine the information in those transmissions with information in an electronic almanac, all in order to figure out the receiver's position on Earth. Once the receiver makes this calculation, it can tell you the latitude, longitude and altitude (or some similar measurement) of its current position. To make the navigation more user-friendly, most receivers plug this raw data into map files stored in memory.
The StreetPilot II, a GPS receiver with built-in maps for drivers
You can use maps stored in the receiver's memory, connect the receiver to a computer that can hold more detailed maps in its memory, or simply buy a detailed map of your area and find your way using the receiver's latitude and longitude readouts. Some receivers let you download detailed maps into memory or supply detailed maps with plug-in map cartridges. A standard GPS receiver will not only place you on a map at any particular location, but will also trace your path across a map as you move. If you leave your receiver on, it can stay in constant communication with GPS satellites to see how your location is changing. With this information and its built-in clock, the receiver can give you several pieces of valuable information:
How far you've traveled (odometer)
How long you've been traveling
Your current speed (speedometer)
Your average speed
A "bread crumb" trail showing you exactly where you have traveled on the map
The estimated time of arrival at your destination if you maintain your current speed
These days, even traffic lights are keeping an eye on you.
As children playing hide and seek, there seemed to be so many places where we could hide and never be found. With the world becoming ever smaller through technology, hiding is increasingly difficult. Cameras peer down on us at red lights, in our workplace, in stores and even at home. Now, those cameras are being augmented by new technologies that track our cars, cell phones and possibly any product we buy. This location-tracking technology also is being used to streamline supply chains for corporations, seeking to move products to the market faster, and to monitor assets and prevent inventory loss.
Soon, companies also will be able to track your location. Imagine walking through your local supermarkets, and as you pass through the aisle, an electronic coupon for your favorite cereal is beamed to your phone. However, many privacy advocates are worried about the implications of these new surveillance systems. Such technology means that marketers and others could know your whereabouts at any time.
Tracking Technology
Location tracking is not one, single technology. Rather, it is the convergence of several technologies that can be merged to create systems that track inventory, livestock or vehicle fleets. Similar systems can be created to deliver location-based services to wireless devices. Current technologies being used to create location-tracking and location-based systems include:
Geographic Information Systems (GIS) - For large-scale location-tracking systems, it is necessary to capture and store geographic information. Geographic information systems can capture, store, analyze and report geographic information.
Global Positioning System (GPS) - A constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). A GPS receiver, like the one in your mobile phone, can locate four or more of these satellites, figure out the distance to each, and deduce your location through trilateration. For trilateration to work, it must have a clear line of sight to these four or more satellites. GPS is ideal for outdoor positioning, such as surveying, farming, transportation or military use (for which it was originally designed). See How GPS Receivers Work for more information.
Artist's concept of the GPS satellite constellation
Radio Frequency Identification (RFID) - Small, battery-less microchips that can be attached to consumer goods, cattle, vehicles and other objects to track their movements. RFID tags are passive and only transmit data if prompted by a reader. The reader transmits radio waves that activate the RFID tag. The tag then transmits information via a pre-determined radio frequency. This information is captured and transmitted to a central database. Among possible uses for RFID tags are a replacement for traditional UPC bar codes. See How RFIDs Work for more information.
Wireless Local Area Network (WLAN) - Network of devices that connect via radio frequency, such as 802.11b. These devices pass data over radio waves and provide users with a network with a range of 70 to 300 feet (21.3 to 91.4 meters).
Any location tracking or location-based service system will use one or a combination of these technologies. The system requires that a node or tag be placed on the object, animal or person being tracked. For example, the GPS receiver in a cell phone or an RFID tag on a DVD can be used to track those devices with a detection system such as GPS satellites or RFID receivers. Next , we'll take a look at how location tracking can be used to streamline supply chains and track fleets of trucks, ships and planes.
Types of Tracking
Companies are finding location-tracking technologies ideal for better managing inventories or fleets of vehicles. Knowing the exact location of each piece of inventory helps to control the supply chain and saves money by not losing those assets that are in transit. Companies, such as retailers, must consider how to track inventory across a wide area, either country or state, and in a smaller area, such as the warehouse or store. Wide-Area Tracking On a large scale, companies must track their vehicle fleets across the country or the world. GPS is the ideal tracking technology for tracking over large areas. To do this, every vehicle needs to be equipped with a GPS receiver. As the vehicle crosses the country, the GPS satellites track the truck's position. With GPS, the operator can request positioning at anytime. However, GPS is limited in smaller areas or indoors. Local-Area and Indoor Tracking A good example of where GPS would not be suitable for tracking items is in a warehouse or hospitals. The accuracy provided by GPS is not sufficient for such a small scale. Consider all of the medical equipment, wheelchairs, gurneys and even patients that need to be tracked. GPS is not a practical or cost-effective solution.
For smaller areas, companies and healthcare organizations would likely use a network of RFID tags and readers to monitor the location of assets or inventory. A wireless LAN also would be more suitable. In such a system, each asset would be tagged with an RFID tag, and readers would be placed in strategic locations to be able to accurately read those tags within a matter of inches. A hospital worker would be able to find the exact room a wheelchair is located and retailers would be able to locate an item on any given shelf. Another example of how this technology is already being deployed is in tracking children in some amusement parks. A child can wear a wristband with an embedded RFID tag. Park staff can track that tag through location receivers positioned around the park. One system in use at Legoland in Denmark even allows for the tag identification number to be registered with the parents' mobile phone. Location tracking isn't limited to just allowing an organization to know where its assets are, these technologies also will help retailers and marketers find you to better target their key markets.
Location-based Services
Mobile phones are becoming more than just a way to call a friend, they are now allowing us to organize our lives, connect to the Internet, shop and take photos. Soon, new location-based services will be offered as new location-aware technology is rolled out. These location-based services will offer personalized services that are connected the specific location.
New location-based services could set up zones of radio signals that send coupons and other announcements to a consumer's wireless device.
Currently, the most recognized location-based service is the navigation systems found in many new cars. As these technologies advance, it will be easier to find the services you are looking for. For example, if you are looking for an ATM, you just ask for it and the system gives you the location and directions. Other services include traffic advisories and roadside assistance. On a smaller scale, wireless LANs will be set up in malls and other areas of commerce to locate wireless devices equipped to receive messages. Here is where retailers can send coupons or other offers to your cell phone as you walk through their stores. Shoppers will likely have the choice to opt out of these services. The success or failure of location-based services largely depends on the roll out of E911 Phase 2 deployment, which is requiring wireless service providers to more accurately locate cell phones in case of emergencies.
Enhanced 911
In America, we learn from an early age to call 911 when there's an emergency. When we dial 911, the call is automatically forwarded to a public-safety answering point (PSAP), also called a 911 call center. When the call is answered, the 911 operator is provided with automatic location information (ALI), pinpointing the exact position of the call. Today, many areas also have Enhanced 911 (E-911), which allows a PSAP to determine the general location from where the call originated, but cannot yet pinpoint the location.
According to the Cellular Telephone Industry Association (CTIA), 150,000 emergency wireless calls are made in the United States each day. The government has stepped in to ensure that E-911 capabilities are improved. New technologies being developed by wireless service providers at the demand of the Federal Communications Commission are expected to enhance the location-finding ability of E-911 to locate the exact position of a wireless emergency call. The FCC is rolling out E-911 in phases:
Phase 0 - This is the basic 911 process. Wireless calls are sent to a PSAP. Service providers must direct a call to a PSAP even if the caller is not a subscriber to their service.
Phase I - The FCC's rule requires that a phone number display with each wireless 911 call, allowing the PSAP operator to call back if there is a disconnection.
Phase II - The final phase requires carriers to place GPS receivers in phones in order to deliver more specific latitude and longitude location information. Location information must be accurate within 164 to 984 feet (50-300 meters).
Without Phase II, a caller's location can only be narrowed down to the cell from which the call originated. When Phase II is implemented, a cell-phone user's phone number, or Automatic Number Identification (ANI), and the address and location of the receiving-antenna site will be sent to the E-911 Tandem, the switch that routes 911 calls to the appropriate PSAP based on the ANI-defined geographic location. Once the caller's voice and ANI are transferred to the PSAP, the PSAP operator will be able to view a graphic display that shows the longitude and latitude of the person as accessed through GPS satellites. The operator's computer will link to the ALI database, which stores address data and other information. The implementation of Phase II technology introduces new commercial opportunities. As mentioned in the previous section, location-based services will leverage the infrastructure of E-911 technology to deliver commercial services to phones, including advertising. These new technologies also create concerns over privacy, which we will examine in the next section.
Why 911?
Have you ever wondered why 911 was chosen as the universal emergency code in the United States? Prior to the 1960s, there was no universal number to call for emergency help. In 1967, the Federal Communications Commission met with AT&T to establish such a number, according to the National Emergency Number Association (NENA). But why did they choose 911? Why not 422 or 111? There are several reasons why 911 was chosen. It's a short, easy to remember number, but more importantly, 911 was a unique number -- it had never been designated for an office code, area code or service code.
On February 16, 1968, Alabama Senator Rankin Fite made the first 911 call in the United States in Haleyville, Alabama. The Alabama Telephone Company carried the call. A week later, Nome, Alaska, implemented a 911 system. In 1973, the White House's Office of Telecommunication issued a national statement supporting the use of 911 and pushed for the establishment of a Federal Information Center to assist government agencies in implementing the system.
Location and Tracking Privacy
The words location tracking can lead many to worry about privacy. Some may worry about the government knowing their whereabouts, stalkers spying on them or even a spouse monitoring their movements. Although the technology could allow anyone to find you at any given moment, measures are being taken to prevent this kind of abuse. Wireless companies are ensuring consumers that federal law prevents these scenarios from happening. In 1999, the U.S. Congress amended the Communications Act of 1934 to include a privacy provision by adding section 222, which states:
222 (a)Every telecommunications carrier has a duty to protect the confidentiality of proprietary information of, and relating to ... customers ... (b)A telecommunications carrier that receives or obtains proprietary information from another carrier for purposes of providing any telecommunications service shall use such information only for such purpose, and shall not use such information for its own marketing efforts. (c )(1) PRIVACY REQUIREMENTS FOR TELECOMMUNICATIONS CARRIERS. - Except as required by law or with the approval of the customer, a telecommunications carrier that receives or obtains customer proprietary network information by virtue of its provision of a telecommunications service shall only use, disclose, or permit access to individually identifiable customer proprietary network information in its provision of (A) the telecommunications service from which such information is derived, or (B) services necessary to, or used in, the provision of such telecommunications service, including the publishing of directories. (2) DISCLOSURE ON REQUEST BY CUSTOMERS. - A telecommunications carrier shall disclose customer proprietary network information, upon affirmative written request by the customer, to any person designated by the customer.
This provision is intended to protect consumers' information from being given out. However, consumers must decide how much privacy they are willing to trade for the conveniences and benefits offered by location-tracking technology.
