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RFID - FAQs
 

Why RFID?

The task of receiving, transporting, sorting and shelving materials has exploded in recent years. RFID provides a solution to automate much of this handling and return staff to the business of customer service.

?The use of RFID reduces the amount of time required to perform circulation operations. The most significant time savings are attributable to the facts that information can be read from RFID tags much faster than from bar codes and that several items in a stack can be read at the same time.?

RFID system consists of three components:
 

  • RFID Tag: A tag or transponder that consists of a microchip with an antenna that is electronically programmed with unique information. Each paper-thin tag contains an etched antenna and a microchip with a capacity of more than 64 bits of information. There are three types: read only, WORM (Write-Once-Read-Many), and read/write.

    There are 2 types of tags available;

    RFID Active Tags: Active Tags are radio frequency identification devices which require batteries for their operation. Active tags have a life of about ten years, due to their batteries. Still, active tags are an interesting option that allows higher data transmission rates and greater distances between tag and reader. They also offer better performance in electro magnetically noisy environments.

    RFID Passive Tags: Passive tags are radio frequency identification devices that do not have any internal power source. Their energy source is the power emitted from adjacent antennas.
     

  • RFID Reader: A reader or sensor with an antenna that interrogates the tags. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from 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 and the reader converts the new waves into digital data.

  • Interface Software: A server or docking station on which the software that interfaces with the RFID is loaded. The software can be linked to the readers and sensors.

Passive Tags vs. Active Tags

Active RFID tags have a battery, which 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, trucks and ships, but they cost significantly more, making them prohibitively expensive to put on low-cost items. Most companies are focusing on passive UHF tags, which cost fewer than 50 cents today in volumes of 1 million tags or more.

What will be RFID tag read range?

The read range of passive tags depends on many factors: the frequency of operation, the power of the reader, interference from metal objects or other radio frequency devices. In general, low-frequency tags are read from a foot or less. High frequency tags are read from about three feet and UHF tags are read from 10 to 20 feet. Where longer ranges are needed, active tags use batteries to boost read ranges to 300 feet or more. Passive tags are undoubtedly less expensive than active tags and can be disposed of with the product?s packaging.

How much information can the tag store?

It depends on the vendor and the application, but typically a tag would carry no more than 2KB of data enough to store some basic information about the item the tag is on. Companies are now looking at using a simple "license plate" tag containing a unique 96-bit serial number, known as the Electronic Product Code (EPC). The EPC was developed by the RFID Center as a successor to the bar code to provide more detailed information about a product (e.g., where an item originated or the date of its production) and to better identify specific products as they move through the global supply chain.

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.

Which RFID Frequency is suitable for me?

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.

Is RFID better than using 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.

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.

What are initial benefits of RFID technology?

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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