How RFID Works.docx

1、How RFID WorksHow RFID Works?1. Introduction to How RFID WorksLong 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

2、 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 of the door. No longer will you have to wait a

3、s 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 connect to a large network that will send information on your products to the ret

4、ailer and product manufacturers. Your bank will then be notified and the amount of the bill 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

5、each product they make from the time its made until its pulled off the shelf and tossed in a shopping cart.Outside the realm of retail merchandise, RFID tags are tracking vehicles, airline passengers, Alzheimers patients andpets. Soon, they may even track your preference for chunky or creamy peanut

6、butter. Some critics say RFID technology is becoming too much a part of our lives - that is, if were even aware of all the parts of our lives that it affects.2. Reinventing the Bar CodeAlmost everything that you buy from retailers has a UPC bar codeprinted on it. These bar codes help manufacturers a

7、nd 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 fingerprintsmade of machine-readable parallel bars that store binary code.Created in the early 1970s to s

8、peed 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 t

9、echnology, 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 b

10、etter 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 wont entirely replace bar codes in the near future - far too many retail outlets currently use UPC scanners in

11、 billions of transactions every year. But as time goes on well 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 technolog

12、y in payments through special credit cards and smart phones - well get into that later.In addition to retail merchandise, RFID tags have also been added to transportation devices like highwaytoll passcardsandsubwaypasses. Because of their ability to store data so efficiently, RFID tags can tabulate

13、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 me

14、dical history to an RFID tag? How about your home address or your babys safety? Lets look at two types of RFID tags and how they store and transmit data before we move past grocery store purchases to human lives.3. RFID Tags Past and Present RFID technology has been around since 1970, but until rece

15、ntly, 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, which were shipped over long distances. These original tags, called inductively coupled RFID tags, were complex systems of metal coils, antenna

16、e 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 iselectromagnetic. Because of this, you can create a magnetic field withelectricity, and you can create electrical cur

17、rent with a magnetic field. The name inductively coupled comes from this process - the magnetic fieldinductsa current in the wire.Capacitively coupled tagswere created next in an attempt to lower the technologys cost. These were meant to be disposable tags that could be applied to less expensive mer

18、chandise 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.Motorolas BiStatix RFID tagswere the frontrunners in this technology. They used a silicon chip that wa

19、s only 3millimeters wide and stored 96 bits of information. This technology didnt catch on with retailers, and BiStatix was shut down in 2001.Newer innovations in the RFID industry includeactive, semi-active and passive RFID tags.These tags can store up to 2 kilobytes of data and are composed of a m

20、icrochip, antenna and, in the case of active and semi-passive tags, abattery. The tags 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 tags microchip waits to be read. The tags antenna receives electromag

21、netic energy from an RFID readers antenna. Using power from its internal battery or power harvested from the readers electromagnetic field, the tag sends radio waves back to the reader. The reader picks up the tags radio waves and interprets the frequencies as meaningful data.Inductively coupled and

22、 capacitively coupled RFID tags arent used as commonly today because they are expensive and bulky. In the next section, well learn more about active, semi-passive and passive RFID tags.4. Active, Semi-passive and Passive RFID Tags Active, semi-passive and passive RFID tags are making RFID technology

23、 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 internalbatteriesto power their circuits. An active tag also uses its battery to broadcastradiowaves to a reade

24、r, 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 fre

25、quencies 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 tags range to over 300 feet (100 meters).Like other wireless devices, RFID tags broadcast over a portion of the electromagne

26、tic 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 oftag interferenceorreader interference. RFID systems can use a cellular system called Time Division Multiple Access (TDMA) to make sure the wireles

27、s communication is handled properly.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 dispos

28、able, 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-onlyandWORM

29、(write once, read many). A read-write tags 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 ove

30、rwritten.Most passive RFID tags cost between seven and 20 cents U.S. each. 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 industrys goal is to get the cost

31、 of a passive RFID tag down to five cents each once more merchandisers adopt it.5. 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 pr

32、oducts 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 thereadersthat communicate with the tags and theInternet, which will provide communications lines for the network.Lets 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 milks expiration date and price.