Knowledge About

1. What is automatic identification?
   
2. What is RFID?
   
3. Is RFID better than using bar codes?
   
4. Will RFID replace bar codes?
   
5. Is RFID new?
   
6. If RFID has been around so long and is so great, why aren't all companies using it?
   
7. What has prevented RFID from taking off until now?
   
8. Are any companies using RFID today?
   
9. What are some of the most common applications for RFID?
   
10. Where will the initial benefits of RFID technology be?
    
11. How does an RFID system work?
    
12. What is the difference between low-, high-, and ultra-high frequencies?
    
13. How do I know which frequency is right for my application?
    
14. Do all countries use the same frequencies?
    
15. I've heard RFID can be used with sensors. Is that true?
    
16. How much information can an RFID tag store?
    
17. What's the difference between read-only and read-write RFID tags?
    
18. What's the difference between passive and active tags?
    
19. What is the read range for a typical RFID tag?
    
20. What is tag collision?
    
21. What is energy harvesting?
    
22. What is a chipless RFID tag?
    
23. I've heard that RFID doesn't work around metal and water. Does that mean I can't use it to track cans or liquid products?
    
24. What is an agile reader?
    
25. What are intelligent and dumb readers?
    
26. What is reader collision?
    
27. What is "dense reader" mode?
    

1. What is automatic identification?
Automatic identification, or auto ID for short, is the broad term given to a host of technologies that are used to help machines identify objects. Auto identification is often coupled with automatic data capture. That is, companies want to identify items, capture information about them and somehow get the data into a computer without having employees type it in. The aim of most auto-ID systems is to increase efficiency, reduce data entry errors and free up staff to perform more value-added functions, such as providing customer service. There is a host of technologies that fall under the auto-ID umbrella. These include bar codes, smart cards, voice recognition, some biometric technologies (retinal scans, for instance), optical character recognition (OCR) and radio frequency identification (RFID).
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2. What is RFID?
Radio frequency identification, or RFID, is a generic term for technologies that use radio waves to automatically identify people or objects. There are several methods of identification, but the most common is to store a serial number that identifies a person or object, and perhaps other information, on a microchip that is attached to an antenna (the chip and the antenna together are called an RFID transponder or an RFID tag). The antenna enables the chip to transmit the identification information to a reader. The reader converts the radio waves reflected back from the RFID tag into digital information that can then be passed on to computers that can make use of it.
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3. Is RFID better than using bar codes?
RFID is not necessarily "better" than bar codes. The two are different technologies and have different applications, which sometimes overlap. The big difference between the two is bar codes are line-of-sight technology. That is, a scanner has to "see" the bar code to read it, which means people usually have to orient the bar code toward a scanner for it to be read. Radio frequency identification, by contrast, doesn't require line of sight. RFID tags can be read as long as they are within range of a reader. Bar codes have other shortcomings as well. If a label is ripped or soiled or has fallen off, there is no way to scan the item, and standard bar codes identify only the manufacturer and product, not the unique item. The bar code on one milk carton is the same as every other, making it impossible to identify which one might pass its expiration date first.
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4. Will RFID replace bar codes?
It's very unlikely. Bar codes are inexpensive and effective for certain tasks, but RFIDand bar codes will coexist for many years.
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5. Is RFID new?
RFID is a proven technology that's been around since at least the 1970s. Up to now, it's been too expensive and too limited to be practical for many commercial applications. But if tags can be made cheaply enough, they can solve many of the problems associated with bar codes. Radio waves travel through most non-metallic materials, so they can be embedded in packaging or encased in protective plastic for weatherproofing and greater durability. And tags have microchips that can store a unique serial number for every product manufactured around the world.
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6. If RFID has been around so long and is so great, why aren't all companies using it?
Many companies have invested in RFID to get the advantages it offers. These investments are usually made in closed-loop systems-that is, when a company is tracking goods that never leave its own control. That's because some existing RFID systems use proprietary technology, which means that if company A puts an RFID tag on a product, it can't be read by Company B unless they both use the same RFID system from the same vendor. Another reason is the price. If a company tracks assets within its own four walls, it can reuse the tags over and over again, which is cost-effective. But for a system to work in an open supply chain, it has to be cheap because the company that puts the tag on a case or pallet is unlikely to be able to reuse it.
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7. What has prevented RFID from taking off until now?
One issue is standards. There are well-developed standards for low- and high-frequency RFID systems, but most companies want to use UHF in the supply chain because it offers longer read range-up to 20 feet under good conditions. UHF technology is relatively new, and standards weren't established until recently. Another issue is cost. RFID readers typically cost $1,000 or more. Companies would need thousands of readers to cover all their factories, warehouses and stores. RFID tags are also fairly expensive-20 cents or more-which makes them impractical for identifying millions of items that cost only a few dollars.
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8. Are any companies using RFID today?
Yes. Thousands of companies around the world use RFID today to improve internal efficiencies. Club Car, a maker of golf carts uses RFID to improve efficiency on its production line. Paramount Farms-one of the world's largest suppliers of pistachios-uses RFID to manage its harvest more efficiently. NYK Logistics uses RFID to improve the throughput of containers at its busy Long Beach, Calif., distribution center. And many other companies are using RFID for a wide variety of applications.
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9. What are some of the most common applications for RFID?
RFID is used for everything from tracking cows and pets to triggering equipment down oil wells. It may sound trite, but the applications are limited only by people's imagination. The most common applications are payment systems (Mobil Speedpass and toll collection systems, for instance), access control and asset tracking. Increasingly, companies are looking to use RFID to track goods within their supply chain, to work in process and for other applications.
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10. Where will the initial benefits of RFID technology be?
RFID technology can deliver benefits in many areas, from tracking work in process to speeding up throughput in a warehouse. Visit RFID Journal's Case Studies section to see how companies are using the technology's potential in manufacturing and other areas. As the technology becomes standardized, it will be used more and more to track goods in the supply chain. The aim is to reduce administrative error, labor costs associated with scanning bar codes, internal theft, errors in shipping goods and overall inventory levels.
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11. How does an RFID system work?
An RFID system consists of a tag made up of a microchip with an antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from the field created by the reader and uses it to power the microchip's circuits. The chip then modulates the waves that the tag sends back to the reader, which converts the new waves into digital data.
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12. What is the difference between low-, high-, and ultra-high frequencies?
Just as your radio tunes in to different frequencies to hear different channels, RFID tags and readers have to be tuned to the same frequency to communicate. RFID systems use many different frequencies, but generally the most common are low-frequency (around 125 KHz), high-frequency (13.56 MHz) and ultra-high-frequency or UHF (860-960 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at different frequencies, so you have to choose the right frequency for the right application.
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13. How do I know which frequency is right for my application?
Different frequencies have different characteristics that make them more useful for different applications. For instance, low-frequency tags use less power and are better able to penetrate non-metallic substances. They are ideal for scanning objects with high-water content, such as fruit, but their read range is limited to less than a foot (0.33 meter). High-frequency tags work better on objects made of metal and can work around goods with high water content. They have a maximum read range of about three feet (1 meter). UHF frequencies typically offer better range and can transfer data faster than low- and high-frequencies. But they use more power and are less likely to pass through materials. And because they tend to be more "directed," they require a clear path between the tag and reader. UHF tags might be better for scanning boxes of goods as they pass through a dock door into a warehouse. It is best to work with a knowledgeable consultant, integrator or vendor that can help you choose the right frequency for your application.
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14. Do all countries use the same frequencies?
Most countries have assigned the 125 kHz or 134 kHz area of the radio spectrum for low-frequency systems, and 13.56 MHz is used around the world for high-frequency systems. But UHF RFID systems have only been around since the mid-1990s, and countries have not agreed on a single area of the UHF spectrum for RFID. Europe uses 868 MHz for UHF, while the U.S. uses 915 MHz. Until recently, Japan did not allow any use of the UHF spectrum for RFID, but it is looking to open up the 960 MHz area for RFID. Many other devices use the UHF spectrum, so it will take years for all governments to agree on a single UHF band for RFID. Governments also regulate the power of the readers to limit interference with other devices. Some groups, such as the Global Commerce Initiative, are trying to encourage governments to agree on frequencies and output. Tag and reader makers are also trying to develop systems that can work at more than one frequency, in order to get around the problem.
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15. I've heard RFID can be used with sensors. Is that true?
Yes. Some companies are combining RFID tags with sensors that detect and record temperature, movement and even radiation. One day, the same tags used to track items moving through the supply chain may also alert staff if they are not stored at the right temperature, if meat has gone bad or if someone has injected a biological agent into food.
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16. How much information can an RFID tag store?
It depends on the vendor and the application, but typically a tag carries no more than 2KB of data-enough to store some basic information about the item it is on. Companies are now looking at using a simple "license plate" tag that contains only a 96-bit serial number. The simple tags are cheaper to manufacture and are more useful for applications where the tag will be disposed of with the product packaging. Top

17. What's the difference between read-only and read-write RFID tags?
Microchips in RFID tags can be read-write, read-only or "write once, read many" (WORM). With read-write chips, you can add information to the tag or write over existing information when the tag is within range of a reader. Read-write tags usually have a serial number that can't be written over. Additional blocks of data can be used to store additional information about the items the tag is attached to (these can usually be locked to prevent overwriting of data). Read-only microchips have information stored on them during the manufacturing process. The information on such chips can never be changed. WORM tags can have a serial number written to them once, and that information cannot be overwritten later.
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18. What's the difference between passive and active tags?
Active RFID tags have a transmitter and their own power source (typically a battery). The power source is used to run the microchip's circuitry and to broadcast a signal to a reader (the way a cell phone transmits signals to a base station). Passive tags have no battery. Instead, they draw power from the reader, which sends out electromagnetic waves that induce a current in the tag's antenna. Semi-passive tags use a battery to run the chip's circuitry, but communicate by drawing power from the reader. Active and semi-passive tags are useful for tracking high-value goods that need to be scanned over long ranges, such as railway cars on a track, but they cost more than passive tags, which means they can't be used on low-cost items. (There are companies developing technology that could make active tags far less expensive than they are today.) End-users are focusing on passive UHF tags, which cost less than 40 cents today in volumes of 1 million tags or more. Their read range isn't as far-typically less than 20 feet vs. 100 feet or more for active tags-but they are far less expensive than active tags and can be disposed of with the product packaging.
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19. What is the read range for a typical RFID tag?
There really is no such thing as a "typical" RFID tag, and the read range of passive tags depends on many factors: the frequency of operation, the power of the reader, interference from other RF devices and so on. In general, low-frequency tags are read from a foot (0.33 meter) or less. High-frequency tags are read from about three feet (1 meter) and UHF tags are read from 10 to 20 feet. Where longer ranges are needed, such as for tracking railway cars, active tags use batteries to boost read ranges to 300 feet (100 meters) or more.
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20. What is tag collision?
Tag collision occurs when more than one transponder reflects back a signal at the same time, confusing the reader. Different vendors have developed different systems for having the tags respond to the reader one at a time. These involve using algorithms to "singulate" the tags. Since each tag can be read in milliseconds, it appears that all the tags are being read simultaneously.
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21. What is energy harvesting?
Most passive RFID tags simply reflect back waves from the reader. Energy harvesting is a technique in which energy from the reader is gathered by the tag, stored momentarily and transmitted back at a different frequency. This method may improve the performance of passive RFID tags dramatically.
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22. What is a chipless RFID tag?
"Chipless RFID" is a generic term for systems that use RF energy to communicate data but don't store a serial number in a silicon microchip in the transponder. Some chipless tags use plastic or conductive polymers instead of silicon-based microchips. Other chipless tags use materials that reflect back a portion of the radio waves beamed at them. A computer takes a snapshot of the waves beamed back and uses it like a fingerprint to identify the object with the tag. Companies are experimenting with embedding RF reflecting fibers in paper to prevent unauthorized photocopying of certain documents. Chipless tags that use embedded fibers have one drawback for supply chain uses-only one tag can be read at a time.
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23. I've heard that RFID doesn't work around metal and water. Does that mean I can't use it to track cans or liquid products?
No. Radio waves bounce off metal and are absorbed by water at ultra-high frequencies. That makes tracking metal products or those with high water content problematic, but good system design and engineering can overcome this shortcoming. Low- and high-frequency tags work better on products with water and metal. In fact, there are applications in which low-frequency RFID tags are actually embedded in metal auto parts to track them.
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24. What is an agile reader?
An agile reader is one that can read tags operating at different frequencies or using different methods of communication between the tags and readers.
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25. What are intelligent and dumb readers?
These terms are not precise, but many people use "intelligent reader" to describe one that has the ability not just to run different protocols, but also to filter data and even run applications. Essentially, it is a computer that communicates with the tags. A "dumb" reader, by contrast, is a simple device that might read only one type of tag using one frequency and one protocol. This type typically has very little computing power, so it can't filter reads, store tag data and so on.
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26. What is reader collision?
One problem encountered with RFID is that the signal from one reader can interfere with the signal from another where coverage overlaps. This is called reader collision. One way to avoid the problem is to use a technique called time division multiple access, or TDMA. In simple terms, the readers are instructed to read at different times, rather than both trying to read at the same time. This ensures that they don't interfere with each other. But it also means any RFID tag in an area where two readers overlap will be read twice. So the system has to be set up so that if one reader reads a tag, another reader does not read it again.
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27. What is "dense reader" mode?
This is a mode of operation that prevents readers from interfering with one another when many are used in close proximity to one another. Readers hop between channels within a certain frequency spectrum (in the United States, they can hop between 902 MHz and 928 MHz) and may be required to listen for a Signal before using a channel. If they "hear" another reader using that channel, they go to another channel to avoid interfering with the reader on that channel.

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