RFID FAQ

1. What is Automatic Identification?
2. What is RFID?
3. How does an RFID system work?
4. Are there any health risks associated with RFID and radio waves?
5. What is an Electronic Product Code?
6. What is the difference between RFID and bar codes?
7. Will RFID replace bar codes?
8. Is RFID new?
9. If RFID has been around for so long and is so great, why aren't all companies using it?
10. Is the lack of standards the only thing that has prevented RFID from being more widely used?
11. What is the difference between low, high, and ultra-high frequencies?
12. How do I know which frequency is right for my application?
13. Do all countries use the same low-, high and ultra-high frequencies?
14. 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?
15. What's the difference between passive and active tags?
16. How much information can the tag store?
17. What's the difference between read-only and read-write tags?
18. What is the read range for a typical RFID tag?
19. Are there any standards for RFID?
20. What are some of the most common applications for RFID?
21. What are the most common problems when implementing RFID?

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 are 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, and radio frequency identification (RFID). TOP OF PAGE

2. What is RFID?

Radio Frequency Identification (RFID) is an automatic identification method, relying on storing and remotely retrieving data, using devices called RFID tags or transponders. An RFID tag is an object that can be attached to or incorporated with an number of different things, for the purpose of identification using radio waves. Chip-based RFID tags contain silicon chips and antennas.

3. How does an RFID system work?

An RFID system consists of a tag, which is 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 electromagnetic waves 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; the reader converts the new waves into digital data.

4. Are there any health risks associated with RFID and radio waves?

RFID uses the low-end of the electromagnetic spectrum. The waves coming from readers are no more dangerous than the waves coming to your car radio. TOP OF PAGE

5. What is an Electronic Product Code?

The Electronic Product Code, or EPC, was developed by the Auto-ID Center as a successor to the bar code. It is a numbering scheme that will be used to identify products as they move through the global supply chain. The EPC standards and numbering schemes are governed by the EPCglobal division (see www.epcglobalinc.org) of GS1. TOP OF PAGE

6. What is the difference between RFID and bar codes?

The two are different technologies, which have different applications. In the case of bar codes, a scanner has to "see" the bar code to read it, which means you have to orient the bar code towards 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 the read range. In addition, bar code scanners are limited to reading one bar code at a time, while an RFID reader can read multiple tags simultaneously. If a bar code label is ripped, soiled or falls off, there is no way to scan the item. From a supply chain perspective, the most important difference is that standard bar codes identify only the manufacturer and product, not the unique item. For instance, 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. TOP OF PAGE

7. Will RFID replace bar codes?

Probably not. Bar codes are inexpensive and effective for certain tasks. It is likely that RFID and bar codes will coexist for many years. Today, RFID label tags often have a UPC barcode imprinted on the label to that it can be tracked using either technology. TOP OF PAGE

8. Is RFID new?

Originally developed by the British during World War II, RFID is a proven technology that's been around for many years. Up until now, it's been too expensive and too limited to be practical for many commercial applications. As RFID tags are becoming less expensive, they will solve many of the problems associated with bar codes. TOP OF PAGE

9. If RFID has been around so long and is so great, why aren't all companies using it?

Many companies have invested in RFID systems to get the advantages they offer. These investments traditionally are made in closed-loop systems, where a company is tracking goods that never leave its own control. That's because many existing RFID systems use a proprietary technology or radio frequency range, which means that if company A puts an RFID tag on a product, it can't be read by Company B. But most companies don't have closed-loop systems, and many of the benefits of tracking items come from tracking them as they move from one company to another and even one country to another. TOP OF PAGE

10. Is the lack of standards the only thing that has prevented RFID from being more widely used?

No, another problem is cost. RFID readers typically cost $1,000 or more. Companies would need numerous readers to cover all their factories, warehouses and stores. Depending on the application, RFID tags may be considered fairly expensive - which makes them impractical for identifying millions of items that cost only a few dollars. However, as standards are evolving and prices come down more and more organizations are able to build a business case that supports the deployment of RFID in their environment. TOP OF PAGE

11. What is the difference between low, high, and ultra-high frequencies?

Just as your radio tunes in to different frequency 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- (around 125 KHz), high- (13.56 MHz) and ultra-high frequency, or UHF (850-900 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at specific frequencies, so you have to choose the right frequency for the right application. TOP OF PAGE

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 are better able to penetrate non-metallic substances than UHF tags. They are ideal for scanning objects with high-water content, such as fruit, at close read range. UHF frequencies typically offer better range and can transfer data faster. However, they require higher reader power and are less likely to pass through materials. Because the signal they emit tends to be more "directed," they require a clear path between the tag and reader. UHF tags are usually used for scanning boxes of goods as they pass through a bay door into a warehouse. It is probably best to work with a consultant, integrator or vendor that can help you choose the right frequency for your application. TOP OF PAGE

13. Do all countries use the same low-, high and ultra-high 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. 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, although EPCglobal has made significant progress in this area. Europe uses 868 MHz for UHF and 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 960MHz 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, to get around the problem. TOP OF PAGE

14. 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. TOP OF PAGE

15. What's the difference between passive and 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 longer read ranges, such as railway cars on a track. The problem is that they cost a dollar or more, making them too expensive to put on low-cost items. Companies are focusing on passive UHF tags for standard supply chain applications. 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. TOP OF PAGE

16. 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 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 OF PAGE

17. What's the difference between read-only and read-write tags?

Microchips in RFID tags can be read-write or read-only. 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, or interrogator. 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. Some read-only microchips have information stored on them during the manufacturing process. The information on such chips can never been changed. Other tags can have a serial number written to it once and then that information can't be overwritten later. TOP OF PAGE

18. What is the read range for a typical RFID tag?

The read range of passive tags (tags without batteries) depends on many factors: the frequency of operation, the power of the reader, interference from metal objects or other RF 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, such as for tracking railway cars, active tags use batteries to boost read ranges to 300 feet or more. TOP OF PAGE

19. Are there any standards for RFID?

Yes. International standards have been adopted for some very specific applications, such as tracking animals. Many other standards initiatives are under way. The International Organization for Standardization (ISO) is working on standards for tracking goods in the supply chain using high-frequency tags (ISO 18000-3) and ultra-high frequency tags (ISO 18000-6). EPCglobal, a joint venture set up to commercialize Electronic Product Code technologies, has its own standards process, which was used to create bar code standards. EPCglobal also works with ISO so that EPC protocols can become international standards. TOP OF PAGE

20. 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 tracking goods in the supply chain, reusable containers, high value tools and other assets, and parts moving to a manufacturing production line. RFID is also used for security (including controlling access to buildings and networks) and payment systems that let customers pay for items without using cash. TOP OF PAGE

21. What are the most common problems when implementing RFID?

Because of the way the technology works and the physics of the world we live in, there can be problems making RFID work. Different tags work with different radio frequencies. Depending on the frequency and the type and size of the tag, there can be problems with reading the tags. Items such as metals or liquids absorb or interfere with certain frequencies, so choosing the correct type/size of tag and deciding where to mount it on an object is extremely important to decide before the start of any implementation. After the implementation has been accomplished, workers will need to be trained on how to handle a tag, when attaching it. Tags imbedded in labels, for instance, need to be applied without bending the labels. TOP OF PAGE