Radio Frequency Identification (RFID) can be defined as a method of identifying unique items using radio waves. RFID is based on analog-to-digital conversion technology to transfer data between a moveable item and a reader to identify, track or locate that item. The reader sends a request in the form of electromagnetic waves for identification information to the tag. 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.
In some systems, the link between the reader and the computer is wireless. RFID has several advantages over bar codes such as it can hold more data, has the ability to change the stored data as processing occurs, it does not require line-of-sight to transfer data and is very effective in harsh environments where bar code labels won't work.
Some companies are combining RFID tags with sensors that detect and record temperature, movement, even radiation. Some day, the same tags used to track items moving through the supply chain may also alert staff if goods are not stored at the right temperature, if they have gone bad, or even if someone has injected a biological agent into them.
History of RFIDThe roots of radio frequency identification technology can be traced back to World War II. The Germans, Japanese, Americans and British were all using radar, which had been discovered in 1935 by Scottish physicist Sir Robert Alexander Watson-Watt — to warn of approaching planes while they were still miles away. The problem was, there was no way to identify which planes belonged to the enemy and which were a country’s own pilots returning from a mission. The Germans discovered that if pilots rolled their planes as they returned to base, it would change the radio signal reflected back. This crude method alerted the radar crew on the ground that these were German planes and not allied aircrafts.
Under Watson-Watt, who headed a secret project, the British developed the first active identify friend or foe (IFF) system. They put a transmitter on each British plane. When it received signals from radar stations on the ground, it began broadcasting a signal back that identified the aircraft as friendly. RFID works on this same basic concept. A signal is sent to a transponder, which wakes up and either reflects back a signal (passive system) or broadcasts a signal (active system).
RFID Tag
RFID tag is a microchip attached to an antenna that is packaged in a way that it can be applied to an object. The tag picks up signals from and sends signals to a reader. The tag contains a unique serial number, but may have other information, such as a customers' account number. A typical RFID tag can carry no more than 2KB of data, which is 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.
Microchips in RFID tags can be read-write, read-only, or write once read many (WORM). With read-write chips, one 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 been changed. WORM tags can have a serial number written to it once and then that information can't be overwritten later.
RFID tags can also be classified as active, passive and semi-passive. 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.
Advancements in the RFID technology have enabled companies to produce chipless RFID tags. A Chipless RFID uses RF energy to communicate data but they 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. However, chipless tags that use embedded fibers have one drawback for supply chain uses i.e. only one tag can be read at a time.
Every RFID chip has a read range i.e. distance from which a tag can be read. Read range depends on a number of factors, including the frequency of the radio waves being used for tag-reader communication, the size of the tag antenna, the power output of the reader, and whether the tags have a battery to broadcast a signal or gather energy from a reader and merely reflect a weak signal back to the reader. Battery-powered tags typically have a read range of 300 feet (100 meters). These are the kinds of tags used in toll collection systems. High-frequency tags, which are often used in smart cards, have a read range of three feet or less. UHF tags-the kind used on pallets and cases of goods in the supply chain-have a read range of 20 to 30 feet under ideal conditions. If the tags are attached to products with water or metal, the read range can be significantly less. If the size of the UHF antenna is reduced, that will also dramatically reduce the read range. Increasing the power output could increase the range, but most governments restrict the output of readers so that they don't interfere with other RF devices, such as cordless phones.
RFID Reader is a device used to communicate with RFID tags. The reader has one or more antennas, which emit radio waves and receive signals, back from the tag. The reader is also sometimes called an interrogator because it "interrogates" the tag.
There are many different RFID reader makers. They may make smart readers or dumb readers. Some focus only on UHF. Others sell low, high and ultra-high frequency systems. RFID readers can be classified as intelligent and dumb readers. An intelligent reader 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. And it typically has very little computing power, so it can't filter reads, store tag data and so on.
Applications of RFID Technology
- RFID technology offers several consumer benefits. Its application in supply chain enables reduction in costs and improving the overall efficiencies. Companies can pass some of these savings on to consumers to try to gain market share from less efficient competitors.
- It can be used by retailers to expedite returns and by manufacturers to manage warrantee claims and improve after-sales support of items such as computers and DVD players.
- It can reduce the counterfeiting of pharmaceutical drugs and insure the integrity of products purchased by consumers.
- It can also be used to secure the food supply and prevent terrorists from sneaking weapons of mass destruction into a country through shipping containers.
- Hitachi, the Japanese high-technology company, has developed a very tiny RFID chip, called the mu-chip, designed to help governments prevent the counterfeiting of passports, securities and other documents. There have been reports that the European Union and Japan are considering embedding these chips in large bills.
- Ford Motors at its North American plants has rolled out a battery-charging system for its electric vehicles that uses RFID to transmit data about these vehicles and their batteries.
- Nearly 45 colleges in Pune have decided to put a stop to vanishing books and low attendance records, turning to RFID identity cards for help. The colleges have introduced the cards to allow students access to hostels and monitor their classroom attendance. Students only need to swipe his or her card at a reader to record their attendance. At Pune University's Jayakar library, for instance, members don't return books to a librarian or register the books they borrow at a counter behind which the librarian sits. He or she simply places a smart card on one of the three "readers" or devices in the library and the books are automatically registered in his or her account.
- Airbus' A380 double-decker aircraft, which is the world's largest and seats 555 passengers, will have passive RFID chips on removable parts such as life vests to help ease maintenance processes. The jet is equipped with 10,000 radio-frequency identification chips
- Wal-Mart has recently reported that it was "live" with three distribution centers, 104 Wal-Mart stores, and 36 Sam's Clubs reading radio frequency tags on pallets shipped by 57 suppliers. Wal-Mart's top 100 suppliers, plus a few dozen others that volunteered to be part of the initial RFID implement will soon be going live. So far, the biggest impact of RFID has been felt in the area of process review. Wal-Mart associates previously used manually generated pick lists telling them what products needed to be brought from the stockroom out to the sales floor. Now, backroom pick lists are generated automatically for RFID tagged items. RFID is providing visibility of what's really in the back room and what needs to be reordered.
Conclusion
RFID tags are poised to become the most far-reaching wireless technology since the cellphone, according to a market analysis from In-Stat, with worldwide revenues from RFID tags are forecast to jump from US$300 million in 2004 to US$2.8 billion in 2009. During this period, the technology will appear in many industries with significant impact on the efficiency of business processes.
