Glossary | RFID Sourcebook (paperback)

2G: Second Generation. In mobile telephony, 2G protocols use digital encoding and support limited data communication capabilities. Digital technologies such as GSM, TDMA, and CDMA are examples of 2G technology.

2.5G: Second and a half Generation. Extension of 2G wireless systems to increase data bandwidth and provide additional features such as packet-switched connection (for example, GPRS).

2-wire folded dipole: A folded dipole antenna consisting of two straight conductors connected in parallel.

3G: Third Generation. The next generation of wireless digital communication technology offering a substantially higher data rate than 2.5G.

3-wire folded dipole: A folded dipole antenna consisting of three straight conductors connected in parallel.

active tag: An RFID tag that has an on-board power supply (for example, a battery) and electronics to perform specialized tasks. An active tag uses its on-board power to transmit data; it does not use the emitted power of a reader. An active tag can therefore communicate even in the absence of a reader. A read range of 300 feet (91 meters approximately) or more can be achieved using an active tag. These tags are typically more expensive than passive tags.

actuator: A mechanical device for control and movement of some object.

addressability: The ability to address (that is, read and write) the individual memory fields of a tag's microchip.

agile reader: An RFID reader that can operate in different frequencies or uses different tag-to-reader communication protocols.

AIAG: Automotive Industry Action Group. A nonprofit association, AIAG's primary goals are to reduce cost and complexity within the automotive supply chain and to improve speed to market, product quality, employee health and safety, and the environment.

Air Interface Protocol: A set of rules that governs the tag reader communication.

amplitude: The height of a crest or the depth of a trough from the undisturbed position.

amplitude at a certain point: Of a wave is the height or depth of this point from the undisturbed position, and is called positive or negative accordingly.

amplitude modulation: Modulation of the wave amplitude.

annunciator: An electrically controlled signaling or indicator device.

ANSI: American National Standards Institute. It is a private, nonprofit organization that administers and coordinates the U.S. voluntary standardization and conformity assessment system.

antenna gain: In simple terms, an increase in antenna gain means an increase in RF energy output of the antenna in a particular direction or pattern. Antenna gain is measured in decibels, abbreviated as dB.

anti-collision: A mechanism that is used to mediate tag collisions so that a reader can read multiple tags in its read zone.

ASCII: American Standard Code for Information Interchange. This is a standard-based representation of 256 characters that includes the uppercase and lowercase letters from the English alphabet, digits, punctuation marks, and control codes.

ASN: Advanced Ship Notice. An EDI transaction that provides advance shipment data to the recipient. The recipient can then use this data to optimize the received logistics.

attenuate: Decrease in the transmission strength of an antenna's signal.

attenuator: A small device that, when attached to the reader antenna port, attenuates the antenna signal (usually by a fixed amount).

Auto-ID: The mechanism by which a physical object can be identified in an automatic manner. Some examples of Auto-ID are bar code, RFID, biometric (for example, using fingerprint and retinal scan), voice identification, and optical character recognition (OCR) systems.

bar code: A scheme by which textual information is presented as a printed symbol. A bar code can be either one dimensional or two dimensional.

battery-assisted tag: A semi-passive tag.

carrier frequency: Refers to the frequency at which the reader operates.

CDMA: Code Division Multiple Access. This is a 2G radio communication technology that uses the spread spectrum scheme to efficiently utilize the frequency spectrum of transmission.

CEPT: Conférence Européenne des Postes et des Télécommunications (or The European Conference of Postal and Telecommunications Administrations). Established on June 26, 1959, CEPT is an association of European Telecommunications service providers.

checksum: A numeric value that is computed and stored for a block of data in tag memory. When a reader receives the data block, it computes a new checksum for the received data and checks it against the stored checksum value to ensure that this data block has been correctly transmitted.

choke point: A spot or location where a tag can be read while in transit.

circular polarized antenna: An antenna from which electromagnetic waves radiate in a circular pattern. This type of antenna has a shorter read range compared to a linear polarized antenna. In contrast to a linear antenna, however, a circular antenna is largely insensitive to tag orientation in its read field.

closed-loop system: An RFID system that is used inside the four walls of a business. Because the information about the tagged object is never shared outside the business, such a system can be proprietary (that is, might not use open standards).

commissioning a tag: When a tag is created and is uniquely associated with an object.

constructive interference: This occurs in case of a multipath when an original reader antenna wave is imposed on a reflected wave with an exactly matching waveform resulting in strengthening of the original signal.

contactless smart card: A special type of passive RFID tag that is read when in close proximity of a reader. No physical contact between the tag and the reader is necessary for reading.

coupling: A mechanism based on which the transfer of energy takes place from a reader to a tag.

coupling element of a reader: A reader antenna as it creates a electromagnetic field to couple with the tag.

CPGs: Consumer Packaged Goods. These classes of goods are consumed and need to be replenished periodically. Examples are food items, beverages, apparel, and cleaning goods.

CRC: Cyclic Redundancy Check. A type of checksum.

crest: The highest point of a wave.

CW: Continuous Wave. This is a radio wave with constant frequency and amplitude. From a communication's viewpoint, a CW does not have any embedded information in it, but can be modulated to transmit a signal.

cycle: One complete wavelength of oscillation of a wave.

data transfer rate: The maximum rate at which a reader can read the data from a tag. It is expressed in bits/second or bytes/second.

dB: Decibel. A unit for measuring antenna gain and other types of quantities such as reader power output.

decommissioning a tag: When a tag is disassociated with the tagged object.

destructive interference: This occurs in case of a multipath when an original reader antenna wave is imposed on a reflected wave with exactly the opposite waveform resulting in cancellation of the original signal.

die: Consists of an individual tag microchip on a silicon wafer. Plural: dice.

dipole: A type of tag antenna consisting of a straight electric conductor of a specific length that is interrupted at the center. The total length of a dipole antenna is half the wavelength of the frequency used.

discover: A reader is said to discover a tag when it reads a new tag that is not on its tag list.

discovery time: Time when a tag is discovered by a reader.

DoD: U.S. Department of Defense.

dollarization: The process by which a foreign country (for example, Ecuador) adopts the U.S. dollar as its national currency.

duty cycle: The time for which a reader can emit RF-energy to read tags.

EAN: European Article Numbering. A popular bar code symbology standard used in Europe. This is the European equivalent of UPC symbology.

EAN International: European Article Numbering International. A nonprofit European organization that administers EAN.

EAS: Electronic Article Surveillance. Technology for detecting item theft at retail stores, libraries, and so on. Simple RF devices that can either be turned on or off are generally used for this purpose.

ECC: Electronic Communications Committee. ECC is the committee that brings together the radio- and telecommunications regulatory authorities of the 45 CEPT member countries.

EDI: Electronic Data Interchange. An ANSI X12-based standard format used for exchanging business data such as ASN, invoices, and purchase orders.

EEPROM: Electrically Erasable, Programmable, Read-Only Memory. An EEPROM retains its data even when the power is turned off.

EIRP: Equivalent Isotropic Radiated Power. A measure of a reader's antenna power used in the U.S. It is generally expressed in watts. EIRP = 1.64 ERP.

electromagnetic waves: Created by electrons in motion and consist of oscillating electric and magnetic fields. These waves can pass through a number of different material types.

electronic pedigree: A secure electronic record that contains information about the movement of a particular product through the supply chain.

electronic signature: A unique electronic identification code of an item.

EPC: Electronic Product Code. A license-plate type identifier that can uniquely identify an item in a supply chain. This is currently owned by EPCglobal.

EPCglobal: A joint venture between UCC and EAN International to commercialize EPC.

ERO: European Radiocommunications Office. It supports ECC of the CEPT.

ERP: Effective Radiated Power. A measure of a reader antenna power used in Europe. It is generally expressed in watts.

ERP: Enterprise Resource Planning. This set of activities enables a business to manage its various aspects (for example, order, inventory, and customer service).

ESD: Electrostatic Discharge. ESD is a sudden flow of electric current through a material that is an insulator under normal circumstances. If a large potential difference exists between the two points on the material, the atoms between these two points can become charged and conduct electric current.

ETSI: European Telecommunications Standards Institute. ETSI is an independent, nonprofit organization whose mission is to produce telecommunications standards for today and for the future.

excite: A term that indicates a passive tag microchip drawing power from a reader's signal to properly energize itself.

factory programmed: An RO tag whose identification data was written at the time of manufacturing. Once written, the data cannot be changed because it is etched in the tag microchip.

false read: Phantom read.

far field: The area beyond one full wavelength of the RF wave emitted from a reader antenna.

FCC: Federal Communications Commission. The FCC is an independent U.S. government agency, directly responsible to Congress. The FCC was established by the Communications Act of 1934 and is charged with regulating interstate and international communications by radio, television, wire, satellite, and cable. The FCC's jurisdiction covers the 50 states, the District of Columbia, and U.S. possessions.

field programmable: A WORM or RW tag whose identification and other data can be written at the time when it is needed by the tag consumer. Once written, the tag data may or may not be rewritten depending on whether the tag is RW or WORM, respectively.

firmware: Software stored in the ROM of a device.

Flash: A type of constantly powered nonvolatile memory that can be erased and reprogrammed in units of memory (called blocks).

folded dipole: A type of tag antenna consisting of two or more straight electric conductors connected in parallel and each half the wavelength (of the used frequency) long.

FRAM: Ferroelectric RAM. A type of random access memory that combines the fast read and write access with the capability to retain data when power is turned off. It also has low power requirements. Contrary to its name, FRAM does not contain iron, but compounds such as lead zirconate titanate (PZT).

frequency: The number of cycles in a second. The frequency of a wave is measured in hertz (abbreviated as Hz), named in honor of the German physicist Heinrich Rudolf Hertz. If the frequency of a wave is 1 Hz, it means that the wave is oscillating at the rate of one cycle per second. It is common to express frequency in KHz (or kilohertz = 1,000 Hz), MHz (or megahertz = 1,000,000 Hz), or GHz (or gigahertz = 1,000,000,000 Hz).

frequency band: A range of frequencies on the electromagnetic spectrum.

frequency hopping: An RF transmission scheme that minimizes interference among several devices.

GIAI: Global Individual Asset Identifier. This is used to identify immovable asset as well as fixed inventory of a business.

GLN: Global Location Number. This is used for representing location, trading partners, and legal entities.

GPS: Global Positioning System. Used to compute the geographical location at any point on Earth within some limits of accuracy (generally between 33 feet (10 meters) to 328 feet (100 meters); accuracy within 3.3 feet (1 meter) can be achieved using military-approved specialized equipment). Owned by and operated by the DoD, GPS is available for general use around the world.

GPRS: General Packet Radio Service. This is a 2.5G enhancement of GSM that uses packet-switched transmission technology. It has a theoretical maximum transfer rate of 171.2 Kbps although the actual speed usually ranges between 56 to 114 Kbps. It is typically used for continuous connection to the Internet from mobile phones and computers.

GRAI: Global Returnable Asset Identifier. This is used for numbering returnable assets such as drums, gas cylinders, and so on.

GSM: Global System for Mobile communications. This is the most widely used 2G digital mobile technology in the world today. GSM uses TDMA and is implemented in the 800, 900, 1800, and 1900 MHz frequencies.

GTAG: Global TAG. This is aimed at facilitating global supply-chain operations in the 862 to 928 MHz (UHF) band. It provides a technical foundation with canonical data sets and applications guidelines.

GTIN: Global Trade Identity Number. This is a globally unique EAN-UCC number for identifying products and services.

HA: High Availability. A system or a system component that is continuously operational for a high percentage of its deployment lifetime.

HDMA: Healthcare Distribution Management Association.

HF: High Frequency. HF ranges from 3 MHz to 30 MHz, with 13.56 MHz being the typical frequency used for HF RFID systems.

IFPMA: International Federation of Pharmaceutical Manufacturers Association.

in-phase: Signals in a multipath that exactly match the wave pattern of the original signal.

inlay: An inlet.

inlet: A fully assembled RFID tag that is not in a usable form.

interrogator: A reader.

ISM: Industrial, Scientific, and Medical. The 2.4 GHz frequency band that is accepted worldwide for operations of industrial, scientific, and medical equipment.

ISO: International Organization for Standardization. ISO is a network of the national standards institutes of 146 countries, on the basis of one member per country, with a Central Secretariat in Geneva, Switzerland, that coordinates the system. ISO is a nongovernmental organization.

Kbps: Kilobits (for example, 1,024 bits) per second.

LF: Low Frequency. Frequencies between 30 KHz and 300 KHz are considered low, with the 125 KHz to134 KHz frequency range being commonly used by RFID systems. A typical LF RFID system operates at 125 KHz.

line of sight: Unobstructed path.

linear polarized antenna: RF waves emanate in a linear patter from this type of antenna. A linear polarized antenna is sensitive to tag orientation in its read field.

micron: One thousandth (1/1000) of a millimeter.

microstrip antenna: A patch antenna.

microwave frequency: This ranges upward from 1 GHz. A typical microwave RFID system operates either at 2.45 GHz or 5.8 GHz, although the former is more common.

modulated backscatter: The type of communication mechanism between a tag and a reader. In this case, a part of the RF waves emitted by the reader is modulated and reflected back by the tag.

modulation: The process of changing the characteristics of a radio wave to encode some information-bearing signal. Modulation can also mean the result of applying the modulation process to a radio wave.

multipath: RF waves from a reader antenna can get reflected in the presence of RF-opaque objects in the environment. These reflected waves are scattered and might arrive at the reader antenna at a different time via different paths. Waves that arrive in-phase with the original antenna signal enhance the signal, whereas those that arrive out-of-phase cancel it.

near field: The area between a reader antenna and one full wavelength of the RF wave emitted by the antenna.

negative amplitude: The depth of a trough from the undisturbed position.

out-of-phase: Signals in a multipath that are exactly the opposite of the wave pattern of the original signal.

passive tag: An RFID tag that does not have an on-board power supply. A passive tag uses a part of the power emitted by a reader to transmit its data. Therefore, a passive tag can communicate only in the presence of a reader.

patch antenna: An antenna consisting of a rectangular metal foil or plate mounted on a substrate such as Teflon.

period of oscillation: The time taken by a wave to complete one cycle.

persist time: The time for which a reader keeps information from a read tag on its tag list.

phantom read: A spurious read of a nonexistent tag by a reader.

photolithographic process: A chemical etching process used to produce tag microchips on a silicon wafer.

planar antenna: A patch antenna.

POS: Point of Sale. The physical location where a good is sold to a buyer.

positive amplitude: The height of a crest from the undisturbed position.

power: The strength of the radiated RF energy of a reader antenna.

read redundancy: The number times a tag can be read when in the read zone of a reader.

read window: Read zone.

read zone: The three-dimensional region protruding from a reader antenna inside which a tag can be read.

reader: A device that can read from and write data to compatible tags.

reader antenna: Broadcasts the reader transmitter's RF signal into its surroundings and receives tag responses on the reader's behalf.

reader collision: Occurs when the read zones of two or more readers overlap, resulting in interference of signal from one reader with that from another.

reader range: Distance at which a tag can successfully communicate with a reader antenna.

reprogrammable: The ability to rewrite a tag data. Also, an RW tag.

RF: Radio Frequency.

RF-absorbent: A material that allows RF waves to pass through it at the expense of substantial RF energy loss. This property is frequency dependent. Water is RF-absorbent at UHF and microwave frequencies.

RF-friendly: An RF-lucent material.

RF-lucent: A material that lets RF waves pass through it without any substantial loss of RF energy. This property is frequency dependent. Paper is RF-lucent at UHF and microwave frequencies. Metal is RF-lucent at LF and HF frequencies.

RF-opaque: A material that blocks, reflects, and scatters RF waves. This property is frequency dependent. Metal is RF-opaque at UHF and microwave frequencies.

RF waves: These are electromagnetic waves with wavelengths between 0.04 inches (0.1 centimeters) and 621.4 miles (1,000 kilometers). Another equivalent definition in terms of frequency is radio waves are electromagnetic waves whose frequencies lie between 30 Hz and 300 GHz. Other electromagnetic wave types are infrared, visible light wave, ultraviolet, gamma-ray, x-ray, and cosmic-ray. RFID uses radio waves that are generally between the frequencies of 30 KHz and 5.8 GHz.

RFID: Radio Frequency Identification. A technology that uses radio waves to automatically identify physical objects.

RO: Read-only. A tag that can be written only once in its lifetime. The data is burned into the tag at the factory during the manufacturing stage.

ROM: Read-only Memory. A type of memory, which once written, can never be modified.

RW: Read-write. A tag whose data can be rewritten multiple times.

SAW: Surface Acoustic Wave. A technology that uses a low-power 2.45 GHz frequency to generate surface waves on a piezoelectric material. A part of this wave is converted back to an RF signal, which can then be received and decoded by a reader to extract the embedded data.

scanner: A device that can transmit and receive RF waves. A scanner is an integral part of a reader.

semi-active tag: A semi-passive tag.

semi-passive tag: A semi-passive tag has an on-board power supply. This is used to power its on-board electronics, but is not used for data transmission. A semi-passive tag uses a part of the power emitted by a reader to transmit its data. Therefore, a semi-passive tag can communicate only in the presence of a reader.

sensor: A device that can detect a physical stimulus. A large variety of sensors exist today (for example, temperature, mechanical, light, and chemical). A sensor can convert the detected signal into some kind of electrical or electronic signal.

signal attenuation: Weakening of RF energy (for example, when it passes through an RF-absorbent material).

silicon wafer: A circular slice of silicon a few inches in diameter on which a large number of microchips can be produced.

singulation: A mechanism by which a reader can uniquely identify a single tag among several tags present in the read zone.

smart label: This is a bar code label that has an RFID tag embedded in it.

SNMP: Simple Network Management Protocol. A standard used for monitoring and management of network devices.

spread spectrum: A form of wireless communications in which the frequency of the transmitted signal is intentionally varied. This results in a much greater bandwidth than the signal would have if its frequency were not varied.

SRD: Short-Range Devices. This device types include RFID.

SSCC: Serial Shipping Container Code. This is used to identify shipping units such as a pallet, case, carton, and so on.

sweethearting: When checkout personnel removes an item tag without accepting any payment or accepts a sum that is less than the item's sale price.

symbology: A method that translates textual information into a printed symbol for a bar code.

tag: A device that can generate, store, and transmit data to a reader in a contactless manner using radio waves.

tag alignment: Positioning of a tag antenna with respect to the reader antenna.

tag antenna: This is used for drawing energy from the reader's signal to energize the tag and for sending and receiving data from the reader. A tag antenna is physically attached to the tag microchip. The antenna geometry is central to the tag's operations.

tag collision: Occurs when more than one tag in the read zone of a reader attempts to communicate with the reader at the same time.

tag list: The list of tags last read by a reader.

tag orientation: Tag alignment.

TCO: Total Cost of Ownership. The sum total cost of owning a product by adding its purchase price and maintenance costs for the duration of ownership.

TDMA: Time Division Multiple Access. A digital wireless transmission scheme which assigns unique time slots to users within the channel to share access to a single radio frequency channel without interference. In context of RFID, this technique can be used for resolving reader collision. Using this technique, the readers read tags at different times, and thus can avoid any interference with one another.

transponder: A tag that can act both as a transmitter and a receiver. This tag only transmits when interrogated by a reader. The tag enters into a sleep or low-power state when not being interrogated by a reader. Thus, not all tags can be called transponders.

trough: The lowest point of a wave.

UCC: Uniform Code Council. A nonprofit organization that administers UPC in North America.

UHF: Ultra High Frequency. Frequencies between 300 MHz and 1 GHz are called ultra high frequencies. A typical passive UHF RFID system operates at 915 MHz in the U.S. and at 868 MHz in Europe. A typical active UHF RFID system operates at 315 MHz and 433 MHz.

UID: Unique Identification. This is a U.S. Department of Defense numbering scheme for asset tracking.

UPC: Uniform Product Code. A popular bar code symbology standard used in North America.

wave: A disturbance that transports energy from one point to another.

wavelength: The distance between two consecutive crests or two consecutive troughs.

WHO: World Health Organization.

WMS: Warehouse Management System. A system used for managing warehouse processes and operations.

WORM: Write Once, Read Many. A passive/active tag that can be written only once in its lifetime. This tag can only be read after it has been written.

write rate: The rate at which data is written to a tag. This involves data transfer from the reader to the tag, writing to the tag memory, and validating that the data has been correctly written.