A barcode is a series of parallel black bars and white spaces, both of varying widths. Bars and spaces together are called elements. Different combinations of the bars and spaces represent different characters, such as numbers or letters. Each combination or sequence of bars and spaces is a code that can be translated into information such as price, product type, place of manufacture, or origin of shipment.
Barcodes are simple to use, accurate, and quick. Almost everyone is familiar with their use in retail establishments. They are also often used in ware-houses and manufacturing for selecting items from storage, receiving goods, and shipping.
The FDA requires that a product's national drug code be placed on the container label and outer wrapper on most prescription drugs and about 70 percent of over-the-counter drugs and on blood and blood components intended for transfusion. The U.S. Food and Drug Administration (FDA) estimates that this will prevent nearly 500,000 adverse events and blood transfusion errors and save $98 billion in reduced healthcare costs over a two year period.
The barcode itself does not actually contain detailed information. The barcode simply provides a reference number that cues a computer to access information. A barcode reader is required to read a barcode. Barcode readers may be fixed, portable batch, or portable RF. Fixed readers are attached to a host computer and terminal, and transmit one item at a time as the data is scanned. Battery-powered portable batch readers store data into memory for batch transfer into a host computer at a later time. The portable RF reader can transmit data in real-time, on-line.
The basic reader consists of a scanner and a decoder. Scanners capture the image of the barcode, and the decoder takes the digitized bar space patterns, decodes them, and transmits the decoded data to the computer.
There are several types of scanners. Laser scanners use a single spot of light to sweep across the barcode in a linear fashion. CCD scanners use an LED array with thousands of light detectors; the entire barcode image is captured and then transmitted. Automatic scanners are in a fixed position and read barcodes as they go by on a conveyor. Handheld scanners, such as wands, are portable and may be carried from place to place, as in a warehouse.
When a scanner is passed over the barcode, the dark bars absorb the scanner's light while the light spaces reflect it. A photocell detector receives the reflected light and converts it into an electrical signal. A low electrical signal is created for the reflected light and a high electrical signal is created for the dark bars. The width of the element determines the duration of the electrical signal. The decoder then decodes the signal into the characters represented by the barcode and passes it to a computer in traditional data format.
There are different types of barcodes. Some bar-codes are entirely numeric, whereas others have numeric and alphabetic characters. The type used is dependent upon the implementation, the data that needs to be encoded, and how the barcode is to be printed. There are several barcode standards, called symbologies, each serving a different purpose. Each standard defines the printed symbol and how the scanner reads and decodes the printed symbol.
The Uniform Product Code (UPC) has been the North American standard for several decades. Others include the Automotive Industry Action Group (AIAG), the European Article Numbering System (EAN), and the Reduced Space Symbology (RSS)—an emerging standard for compressing barcodes so that they can fit into small spaces such as a prescription bottle, and the Global Trade Item Number (GTIN) or "Gee-tin," which can read and store other types of code.
Radio frequency identification (RFID) could become the most far-reaching wireless technology since the cell phone. RFID is a method of remotely storing and retrieving data using a small object attached to or incorporated into a product. Its purpose is to enable data to be transmitted via a portable device called a tag, read by a reader, and processed according to the needs of the particular application.
Transmitted data may provide information about product location, or specifics such as color, price, or purchase date. In some systems a return receipt can be generated. RFID tags contain far more detailed information than can be placed on a barcode. Some tags hold enough information to provide routing information for shipping containers, as well as a detailed inventory of what is inside the container.
An RFID system consists of tags, tag readers, tag programming stations, circulation readers, sorting equipment, and tag inventory wands. The tag is the key component. Data can be printed or etched on an electronic substrate and then embedded in a plastic or laminated paper tag.
Tags are classified according to their radio frequency: low-frequency, high-frequency, UHF, and microwave. Low-frequency tags are commonly used in automobile anti-theft systems and animal identification. High-frequency tags are used in library books, pallet tracking, building access, airline baggage tracking, and apparel tracking. Low- and high-frequency tags can be used without a license. UHF tags are used to track pallets, containers, trucks, and trailers. UHF cannot be used globally as there is no one global standard. Microwave tags are used in long-range access, such as General Motors' OnStar system.
While most RFID tags are write-once/read-only, there are some that offer read/write capability. These tags would allow tag data to be rewritten if need be.
Also, tags may be either passive or active. Passive tags do not have their own power supply. Their power comes from a minute electrical current induced by an incoming radio-frequency scan. Active tags have their own power source. The lack of a power source makes the passive tag much less expensive to manufacture and much smaller (thinner than a sheet of paper) than an active tag. As a result, the vast majority of RFID tags are passive. However, the response of a passive tag is typically just an ID number. Active tags have longer ranges, the ability to store more information, and are more accurate and reliable.
The tag contains a transponder with a digital memory chip with a unique electronic product code. A stationary or handheld device called an interrogator, consisting of an antenna, transceiver, and decoder, emits a signal creating an electromagnetic zone. When a tag comes within the range of a reader, it detects an activation signal that causes the tag to "wake up" and start sending data. The reader captures the data encoded in the tag's integrated circuit, decodes it, and sends it over a network to a host computer for processing.
RFID tags can contain far more detailed information than barcodes. Barcodes require a clear line of sight between the scanner and the barcode, a need that is absent from the RFID. It is also only possible to scan just one barcode at a time. Within the field of a reader, hundreds of RFID tags could be read within seconds. RFID codes are long enough that every RFID tag may have a unique code, allowing an individual item to be tracked as it changes location. Barcodes are limited to a single code for all stages of movement of a particular product.
Despite its advantages, it is unlikely that RFID will replace barcoding. The cost of tags is prohibitive in many situations, and there is less need to track individual products from origin to final consumer.
During WWII, RFID devices were used to distinguish British planes from inbound German planes. Modern uses include:
The use of RFID has caused some concern for privacy advocates. They feel that it may be a privacy violation for a consumer unaware of the presence an RFID tracking tag, or if they are unable to remove or deactivate it. Other concerns revolve around the ability to fraudulently or surreptitiously read a tag from a distance, and the ability to identify a purchaser through the use of a credit card or a loyalty card.
RFID advocates, however, feel that opposition will lessen as RFID use becomes more widespread and its use across a wide range of industries becomes apparent.
RFID usage is destined to continue and to expand, especially as costs decline and RFID technology is improved.
R. Anthony Inman
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