Glossário de RFID

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Active tag
An RFID tag that has a transmitter to send back information, rather than reflecting back a signal from the reader, as a passive tag does. Most active tags use a battery to transmit a signal to a reader. However, some tags can gather energy from other sources. Active tags can be read from 300 feet (100 meters) or more, but they're expensive (typically more than US$20 each). They're used for tracking expensive items over long ranges. For instance, the U.S. military uses active tags to track containers of supplies arriving in ports.
Addressability
The ability to write data to different fields, or blocks of memory, in the microchip in an RFID transponder.
Agile reader
A generic term that usually refers to an RFID reader that can read tags operating at different frequencies or using different methods of communication between the tags and readers.
Air Interface Protocol
The rules that govern how tags and readers communicate.
Alignment
See Orientation.
American National Standards Institute
An American technical standards body and the representative of the United States to the International Organization for Standardization.
Amplitude
The maximum absolute value of a periodic curve measured along its vertical axis (the height of a wave, in layman's terms).
Amplitude Modulation
Changing the amplitude of a radio wave. A higher wave is interpreted as a 1 and a normal wave is interpreted as a zero. By changing the wave, the RFID tag can communicate a string of binary digits to the reader. Computers can interpret these digits as digital information. The method of changing the amplitude is known as amplitude shift keying, or ASK.
Amplitude shift keying
Changing the amplitude of the wave to communicate data stored on a tag.
ANSI
See American National Standards Institute
Antenna
The tag antenna is the conductive element that enables the tag to send and receive data. Passive, low- (135 kHz) and high-frequency (13.56 MHz) tags usually have a coiled antenna that couples with the coiled antenna of the reader to form a magnetic field. UHF tag antennas can be a variety of shapes. Readers also have antennas which are used to emit radio waves. The RF energy from the reader antenna is "harvested" by the antenna and used to power up the microchip, which then changes the electrical load on the antenna to reflect back its own signals.
Antenna gain
In technical terms, the gain is the ratio of the power required at the input of a loss-free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength at the same distance. Antenna gain is usually expressed in decibels and the higher the gain the more powerful the energy output. Antennas with higher gain will be able to read tags from farther away.
Anti-collision
A general term used to cover methods of preventing radio waves from one device from interfering with radio waves from another. Anti-collision algorithms are also used to read more than one tag in the same reader's field.
Association for Automatic Identification and Mobility
A global trade association for companies that provide products and services related to automatic identification, data collection, networking and information management systems.
Attenuation
The reduction of energy. See signal attenuation.
Attenuator
A device that attaches to a transmission line (a coaxial cable) that reduces the power of the RF signal as the signal travels through the cable from the reader to the antenna. Attenuators usually work by dissipating the RF energy into heat.
Authentication
The verification of the identity of a person, object or process. In RFID, the term is used in two ways. For contactless smart cards and other payments systems, the reader must make sure the transponder is a valid device within the system. That is, someone is not using an unauthorized device to commit fraud. There is also some talk of using EPC technology to authenticate products as a way of reducing counterfeiting.
Auto-ID Center
A non-profit collaboration between private companies and academia that pioneered the development of an Internet-like infrastructure for tracking goods globally through the use of RFID tags carrying Electronic Product Codes. The center closed its doors in September 2003. EPCglobal was set up to continue the work of commercializing EPC technology, and the center's research work is carried on by Auto-ID Labs at universities around the world.
Auto-ID Labs
Nonprofit research labs, headquartered at the Massachusetts Institute of Technology, which continue to do primary research into the development of EPC and related technologies.
Automatic Identification
A broad term that covers methods of collecting data and entering it directly into computer systems without human involvement. Technologies normally considered part of auto-ID include bar codes, biometrics, RFID and voice recognition.
Automatic identification and data capture
A broad term that covers methods of identifying objects, capturing information about them and entering it directly into computer systems without human involvement. Technologies normally considered part of auto-ID include bar codes, biometrics, RFID and voice recognition.
Back channel
See reverse channel.
Backscatter
A method of communication between passive tags (ones that do not use batteries to broadcast a signal) and readers. RFID tags using backscatter technology reflect back to the reader radio waves from a reader, usually at the same carrier frequency. The reflected signal is modulated to transmit data.
Bar code
A standard method of identifying the manufacturer and product category of a particular item. The bar code was adopted in the 1970s because the bars were easier for machines to read than optical characters. The main drawbacks of bar codes main are they don’t, in most cases, identify unique items and scanners have to have line of sight to read them.
Base station
An RFID reader that is connected to a host system.
Battery-assisted tag
These are RFID tags with batteries, but they communicate using the same backscatter technique as passive tags (tags with no battery). They use the battery to run the circuitry on the microchip and sometimes an onboard sensor. They have a longer read range than a regular passive tag because all of the energy gathered from the reader can be reflected back to the reader. They are sometimes called "semi-passive RFID tags."
Beacon
An active or semi-active RFID tag that is programmed to wake up and broadcast its signal at a set intervals.
Bistatic
A bistatic RFID interrogator, or reader, uses one antenna to transmit RF energy to the RFID tag and a different antenna to receive energy reflected back from the tag.
Capacitor
An electric circuit element used to store a charge temporarily. A capacitor usually consists of two metallic plates separated and insulated from each other by a dielectric substance.
Card operating system
The software program stored in the smart card IC, which manages the basic functions of the card, such as communication with the terminal, security management and data management in the smart card file system.
Carrier frequency
A frequency used to transmit data.
Central processing unit
The brains of a computer, which controls all the other parts of the computer.
Checksum
A code added to the contents of a block of data stored on an RFID microchip that can be checked before and after data is transmitted from the tag to the reader to determine whether the data has been corrupted or lost. The cyclic redundancy check is one form of checksum.
Chipless RFID tag
An RFID tag that doesn't depend on a silicon microchip. 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. Chipless tags that use embedded fibers have one drawback for supply chain uses—only one tag can be read at a time.
Circular-polarized antenna
A UHF reader antenna that emits radio waves in a circular pattern. These antennas are used in situations where the orientation of the tag to the reader cannot be controlled. Since the waves are moving in a circular pattern, they have a better chance of hitting the antenna, but circular-polarized antennas have a shorter read range than linear-polarized antennas.
Closed-loop systems
RFID tracking systems set up within a company. Since the tracked item never leaves the company's control, it does not need to worry about using technology based on open standards.
Collaborative planning, forecasting and replenishment
A general term used to describe cooperation between manufacturers and retailers to better match supply of goods with demand for them.
Commissioning a tag
This term is sometime used to refer to the process of writing a serial number to a tag (or programming a tag) and associating that number with the product it is put on in a database.
Compatibility
Two RFID systems are considered compatible if they use the same protocols, frequencies and voltage levels and are able to operate together within the same overall application (see interoperability).
Concentrator
A device connected to several RFID readers to gather data from the readers. The concentrator usually performs some filtering and then passes only useful information from the readers on to a host computer.
Conducted Power
Conducted power is the RF power that is supplied by an RFID system to the antenna. Typically, it is calculated or measured at the cable to antenna connection. In the United States, Federal Communication Commission regulations require a maximum conducted power of 1 Watt.
Conductor
A material, such as aluminum and copper, which readily conducts electricity. Conductors have a significant impact on the performance of RFID tags. Conductors near tags can reflect RF energy in a way that reduces tag performance, and they can also detune the tag.
Contactless smart card
An awkward name for a credit card or loyalty card that contains an RFID chip to transmit information to a reader without having to be swiped through a reader. Such cards can speed checkout, providing consumers with more convenience.
COS
See card operating system
Coupling
See inductive coupling.
CPFR
See collaborative planning, forecasting and replenishment
CPU
See central processing unit
CRC
See cyclic redundancy check
Cryptographic coprocessor
Special circuitry that perform cryptographic calculations, such as modular arithmetic and large integer calculations. These circuits are added to a standard processor core and therefore are called coprocessors.
Cyclic redundancy check
A method of checking data stored on an RFID tag to be sure that it hasn't been corrupted or some of it lost. (See Checksum.)
Data carrier
A medium that holds machine-readable data. Bar codes and RFID tags are types of data carriers. The term is also applied to a carrier frequency used to transmit data.
Data field
An area of memory in RFID microchips that is assigned to a particular type of information. Data fields may be protected (see below) or they may be written over, so a data field might contain information about where an item should be sent. When the destination changes, the new information is written to the data field.
Data field protection
The ability to prevent data stored in a specific area of memory of an RFID microchip from being overwritten. Companies might want to protect the data field that stores an Electronic Product Code, which doesn't change during the life of the product it's associated with.
Data retention
The ability of a microchip to maintain the information stored in EEPROM. RFID tags and other microchips can typically retain data for 10 years or more, but data retention depends on temperature, humidity and other factors.
Data transfer rate
The number of characters that can be transferred from an RFID tag to a reader within a given time. Baud rates are also used to quantify how fast readers can read the information on the RFID tag. This differs from read rate, which refers to how many tags can be read within a given period of time.
dB
See decibel.
dBi
The gain of an antenna compared to an isotropic antenna—that is, an antenna that radiates energy equally in every direction. A typical dipole antenna has a dBi of 2.2 when compared to an isotropic antenna.
dBm
See decibel
dBw
Decibels (dB) referenced to 1.0 watt. Using the decibel formula: dB=10 log(P1/P2), P2 equals 1.0 watt and P1 is in units of watts.
De-tune
UHF antennas are tuned to receive RFID waves of a certain length from a reader, just as the tuner on the radio in a car changes the antenna to receive signals of different frequencies. When UHF antenna is close to metal or metallic material, the antenna can be detuned, resulting in poor performance.
Dead tag
An RFID tag that cannot be read by an interrogator.
Decibel
A unit used to express the ratio between two values, including antenna gain, cable losses and reader power output. The formula for decibel is: dB=10 log (P1/P2). In layman’s terms, dB represents the difference in the intensity of an emitted signal or power where 0 dB is the reference, 3 dB is twice the intensity of 0 dB, 10 dB is 10 times the intensity, and 20 dB is 100 times the intensity and so on. (See also dBi, dBm and dBw.)
Die
The silicon block onto which circuits have been etched to create a microchip.
Dielectric
Unable to conduct direct electric current. Dielectric substances are used as insulators.
Dielectric constant
The measure of a material’s ability to store a charge when an electric field is applied, or its “capacitance.” If a material has a high dielectric constant, it reflects more RF energy and detunes the antenna more, which makes it harder to tag. Examples of materials with a low dielectric constant are dry paper (2), plastics (most are between 2 and 4), and glass (between 5 and 10). Water’s dielectric constant changes: At room temperature it is 80; near boiling it is 55; and when frozen it is 3.2.
Digital certificate
A digital message that contains the identity of an company or organization, its public key combined and a signature of this data from a certificate authority (Trust Center) proving the correctness of this data.
Digital signal processor
As special kind of microprocessor that converts changes in analog waves into digital information. DSPs are used in RFID readers.
Digital signature
A cryptographic protocol that ensures the authenticity as well as the integrity of digital data. A digital signature typically is realized by encrypting the hash value of the data to be protected with the private key.
Digital signature algorithm
A cryptographic algorithm approved by the United States government for use in creating digital signatures.
Dipole
An antenna made of two straight electrical conductors (poles). In an RFID transponder, these are connected to a microchip. The antenna is typically 1/2 wavelength from end to end.
DSP
See digital signal processor
Dual dipole
An antenna that has two dipoles. In an RFID transponder, these are attached to a chip. The dual dipole design greatly reduces the tag’s orientation sensitivity.
Dual interface smart card
A card that contains a microchip that can be read either when in content with a reader or remotely using radio waves.
Dumb reader
A generic term for a reader with limited computing power. It generally converts radio waves from a tag into a binary number and passes it to a host computer with little or no filtering.
Duplex
A channel capable of transmitting data in both directions at the same time. (Half duplex is a channel capable of transmitting data in both directions, but not simultaneously.)
Duty cycle
The length of time the reader can be emitting energy. Regulations in the European Union say readers can be on only 10 percent of the time.
EAN
See European Article Number
EAS
See electronic article surveillance
Edge server
A computer for running middleware or applications that is close to the edge of the network, where the digital world meets the real world. Edge servers are put in warehouses, distribution centers and factories, as opposed to corporate headquarters.
EDI
See Electronic Data Interchange
EEPROM
See Electrically Erasable Programmable Read-Only Memory
Effective isotropic radiated power
A measurement of the output of RFID reader antennas used in the United States and elsewhere. EIRP is usually expressed in watts.
Effective radiated power
A measurement of the output of RFID reader antennas used in Europe and elsewhere. ERP is usually expressed in watts and is not the same as EIRP.
EIRP
See Effective isotropic radiated power
Electrically Erasable Programmable Read-Only Memory
A method of storing data on microchips. Usually bytes can be erased and reprogrammed individually. RFID tags that use EEPROM are more expensive than factory programmed tags, where the number is written into the silicon when the chip is made, but they offer more flexibility because the end user can write an ID number to the tag at the time the tag is going to be used.
Electromagnetic interference
Interference caused when the radio waves of one device distort the waves of another. Cells phones, wireless computers and even robots in factories can produce radio waves that interfere with RFID tags.
Electronic article surveillance
Simple electronic tags that can be turned on or off. When an item is purchased (or borrowed from a library), the tag is turned off. When someone passes a gate area holding an item with a tag that hasn't been turned off, an alarm sounds. EAS tags are embedded in the packaging of most pharmaceuticals. They can be RF-based, or acousto-magnetic.
Electronic Data Interchange
A method of transmitting trade documents in standardized formats.
Electronic pedigree
A secure file that stores data about each move a product makes through the supply chain. Pedigrees can help to reduce counterfeiting of drugs and other products.
Electronic Product Code
A serial, created by the Auto-ID Center, which will complement barcodes. The EPC has digits to identify the manufacturer, product category and the individual item.
EMI
See Electromagnetic interference
Encryption
The scrambling of data in such a way that it can be unscrambled and read only by those for whom it is intended. In RFID systems, encryption is used to protect information store on a transponder's microchip or to prevent the interception of communications between the tag and reader.
Enterprise resource planning
: Software that is designed to be the operating system for large companies. ERP systems manage data across applications and functional areas, such as finance, human resources and supply chain management.
EPC
Electronic Product Code
EPC Discovery Service
An EPCglobal Network service that allows companies to search for every reader that has read a particular EPC tag.
EPC Generation 2
The standard ratified by EPCglobal for the air-interface protocol for the second generation of EPC technologies.
EPC Information Service
Part of the EPC Network. The EPC Information Service is a network infrastructure that enables companies to store data associated with EPCs in secure databases on the Web. The EPC Information Service will enable companies to provide different levels of access to data to different groups. Some information associated with an EPC might be available to everyone. Other information might be available only to a manufacturer's retail customers. The service also includes a number of applications, such as the EPC Discovery Service.
EPC Network
See EPCglobal Network
EPCglobal
A non-profit organization set up the Uniform Code Council and EAN International, the two organizations that maintain barcode standards, to commercialize EPC technology. EPCglobal is made up of chapters in different countries and regions. It is commercializing the technology originally developed by the Auto-ID Center.
EPCglobal Network
The Internet-based technologies and services that enable companies to retrieve data associated with EPCs. The network infrastructure includes the Object Name Service, distributed middleware (sometimes called Savants), the EPC Information Service and Physical Markup Language.
EPROM
See erasable programmable read-only memory
Erasable programmable read-only memory
Non-volatile memory that can be erased by exposing it to intense ultraviolet light. After erasing, EPROM memory can be reprogrammed.
ERP
See Effective radiated power and enterprise resource planning
Error correcting code
A code stored on an RFID tag to enable the reader to figure out the value of missing or garbled bits of data. It's needed because a reader might misinterpret some data from the tag and think a Rolex watch is actually a pair of socks.
Error correcting mode
A mode of data transmission between the tag and reader in which errors or missing data is automatically corrected.
Error correcting protocol
A set of rules used by readers to interpret data correctly from the tag.
ETSI
See European Telecommunications Standards Institute
European Article Number
A system for identifying products developed by EAN International, the bar code standards body in Europe. There are several types of bar codes that use EANs, including EAN-8, EAN-13 and EAN-14.
European Telecommunications Standards Institute
An independent, non-profit organization, whose mission is to produce telecommunications standards for Europe. Based in Sophia Antipolis, France, ETSI is officially responsible for standardization of Information and Communication Technologies, include telecommunications, broadcasting and related areas, such as intelligent transportation, medical electronics and RFID.
Event data
Information related to a transaction or incident with significance to the business. If a tag on a pallet is read as the pallet leaves a dock door, an event is recorded (the pallet was shipped). If a reader reads a tag on a pallet in a storage bay 100 times per minute but the pallet never moves, data is generated, but there is no event.
Excite
The reader is said to "excite" a passive tag when the reader transmits RF energy to wake up the tag and enable it to transmit back.
eXtensible markup language
A widely accepted way of sharing information over the Internet in a way that computers can use, regardless of their operating system.
Factory programming
Some read-only have to have their identification number written into the silicon microchip at the time the chip is made. The process of writing the number into the chip is called factory programming. This data can't be written over or changed.
False read
See phantom read.
Far-field communication
RFID reader antennas emit electromagnetic radiation (radio waves). If an RFID tag is outside of one full wavelength of the reader, it is said to be in the "far field." If it is within one full wavelength away, it is said to be in the "near field." The far field signal decays as the square of the distance from the antenna, while the near field signal decays as the cube of distance from the antenna. So passive RFID systems that rely on far field communications (typically UHF and microwave systems) have a longer read range than those that use near field communications (typically low- and high-frequency systems).
Field programming
Tags that use EEPROM, or non-volatile memory, can be programmed after it is shipped from the factory. That is, users can write data to the tag when it is placed on a product.
Firmware
Coded instructions that are stored permanently in read-only memory. When upgrading a reader to read a new protocol, the firmware usually has to be changed. Some newer readers can be upgraded remotely over a network.
FLASH
A special type of EEPROM that can be erased and reprogrammed in blocks instead of one byte at a time. It is usually written in capital letters, but it is not an acronym.
Fluidic Self-Assembly
A manufacturing process, patented by Alien Technology. It involves flowing tiny microchips in a special fluid over a base with holes shaped to catch the chips. The process is designed to mass assemble billions of RFID tags at very low cost.
Folded dipole
A dipole antenna in which the two poles are connected to each other, as well as to the microchip.
Form factor
The packaging a transponder can be put in. These include thermal transfer labels, plastic cards, key fobs and so on.
Forward channel
The path through which energy passes from the interrogator, or reader, to the RFID tag.
Free air
A term used to describe the reading of an RFID tag that is not attached to anything.
Frequency
The number of repetitions of a complete wave within one second. 1 Hz equals one complete waveform in one second. 1KHz equals 1,000 waves in a second. RFID tags use low, high, ultra-high and microwave frequencies. Each frequency has advantages and disadvantages that make them more suitable for some applications than for others.
Frequency hopping
A technique used to prevent readers from interfering with one another. In the United States, UHF RFID readers actually operate between 902 and 928 MHz, even though it is said that they operate at 915 MHz. The readers may jump randomly or in a programmed sequence to any frequency between 902 MHz and 928 MHz. If the band is wide enough, the chances of two readers operating at exactly the same frequency is small. The UHF bands in Europe and Japan are much smaller so this technique is not effective for preventing reader interference.
Frequency shift keying
A method of communicating data by switching between two slightly different frequencies.
FSK
See frequency shift keying
GCI
See Global Commerce Initiative
GDS
See global data synchronization
Gen 2
See EPC Generation 2
GLN
See Global Location Number
Global Commerce Initiative
In user group founded in October 1999 by manufacturers, retailers and trade industry associations, to improve the performance of the international supply chain for consumer goods through the collaborative development and endorsement of recommended voluntary standards and best practices. Its charter is to drive the implementation of EAN•UCC standards and best practices, including use of EPC.
Global data synchronization
A term that generally refers to the process of ensuring that a manufacturer's master files with product information match those of retailers. GDS is an importan prerequisite to deploying RFID in open supply chains because companies need to ensure that RFID serial numbers refer to the right product information in a database.
Global Location Number
A numbering scheme created by EAN International and the Uniform Code Council to as a means to identify virtually limitless numbers of legal entities, trading parties and locations to support the requirements of electronic commerce (B2B and B2C). Parties and locations that can be identified with GLNs include functional entities (e.g., a purchasing, accounting or returns department), physical entities (e.g., a particular room in a building, warehouse, loading dock, delivery point) and legal entities or trading partners (e.g. buyers, sellers, whole companies, subsidiaries or divisions such as suppliers, customers, financial services companies, or freight forwarders).
Global Positioning System
Developed for and managed by the United States military, GPS is a satellite navigation system. It consists of 24 satellites above the earth. They transmit radio signals to receivers placed on ships, trucks or other large assets that need to be tracked. The receivers compute longitude and latitude and velocity by calculating the difference in the time signals are received from four different satellites. Some companies are integrating RFID and GPS systems to track assets in transit.
Global System for Mobiles
The digital cellular telephone system, widely used in Europe, Asia and Australia.
Global Trade Item Number
A standardized system of identifying products and services created by the Uniform Code Council and EAN International. Product identification numbers, such as EAN/UCC-8, UCC-12, EAN/UCC-13, and EAN/UCC-14, are based on the GTIN.
GPS
Global Positioning System
GSM
See Global System for Mobiles
GTAG
See Global Tag
GTIN
See Global Trade Item Number
Harvesting
A term sometimes used to describe the way passive tags gather energy from an RFID reader antenna.
High-frequency
This is generally considered to be from 3 MHz to 30 MHz. HF RFID tags typically operate at 13.56 MHz. They can be read from less than 3 feet away and transmit data faster than low-frequency tags. But they consume more power than low-frequency tags.
Host system
A computer on a network, which provides services to users or other computers on that network.
Hybrid card
A smart card that has both a contactless IC and a contact IC. Unlike a dual interface card, a hybrid card acts as two separate cards.
Hysteresis
A retardation of an effect when the forces acting upon a body are changed. When corrugated boxes and other materials absorb water and then dry, they are never as RF-friendly as they were before they became moist.
I/O
See input/output
I/O ports
See input-output ports
IC
See integrated circuit
Inductive coupling
In technical terms, inductive coupling is the transfer of energy from one circuit to another by virtue of the mutual inductance between the circuits. In an RFID system that uses inductive coupling, the reader antenna and the tag antenna each have a coil, which together form a magnetic field. The tag draws energy from the field. The microchip uses this energy to change the electrical load on the tag antenna. These changes are picked up by the reader antenna and converted into a unique serial number.
Industrial, Scientific, and Medical bands
A group of unlicensed frequencies of the electromagnetic spectrum.
Inlay
An RFID microchip attached to an antenna and mounted on a substrate. Inlays are essentially unfinished RFID labels. They are usually sold to label converters who turn them into smart labels. They are also sometimes called inlets.
Inlet
See inlay
Input-output ports
Ports on an RFID reader that can be connected to external devices. An input port might be connected to a photoelectric eye to turn on the reader when an object enters the reader field. An output device might be connected to a door that opens when a tag is read.
Input/output
Ports on a reader. Users can connect devices, such as an electronic eye to the input port so that when an object breaks the beam of the electronic eye the reader begins reading. Devices can also be connected to an output part, so that when a tag is read, a conveyor is turned on or a dock door opened.
Integrated circuit
A microelectronic semiconductor device comprising many interconnected transistors and other components. Most RFID tags have ICs.
Intelligent reader
A generic term that is sometimes used to describe a reader that has the ability to filter data, execute commands and generally perform functions similar to a personal computer.
Intentional radiator
A device that produces a RF signal for the purpose of data communications. Examples. Include garage door openers, cordless phones, RFID transmitter and so on.
International Organization for Standardization
A non-governmental organization made up of the national standards institutes of 146 countries. Each member country has one representative and the organization maintains a Central Secretariat in Geneva, Switzerland, that coordinates the system.
Interoperability
In computing, the term refers to the ability to exchange and use information among disparate software systems. In RFID, the term generally refers to the ability of tags and readers from different vendors to communicate.
Interposer
A device used to connect a microchip to an antenna to create an RFID transponder. Interposers make an electrical connection to the tiny pads on the chip and to create leads that can be bonded to an antenna.
Interrogation zone
The area in which a passive interrogator can provide enough energy to power up a passive tag and receive back information. Also called the read field or reader field. Tags outside the interrogation zone do not receive enough energy from the interrogator to reflect back a signal.
Interrogator
See reader,
ISM
A group of unlicensed frequencies of the electromagnetic spectrum.
ISO
See International Organization for Standardization
ISO 10536
The international standard for proximity cards
ISO 11784
The international standard defining frequencies, baud rate, bit coding and data structures of the transponders used for animal identification.
ISO 14443
A set of international standards covering proximity smart cards.
ISO 15693
The international standard for vicinity smart cards.
ISO 18000
A series of international standards for the air interface protocol used in RFID systems for tagging goods within the supply chain.
ISO 7816
A set of international standards covering the basic characteristics of smart cards, such as physical and electrical characteristics, communication protocols and others.
Isotropic
Identical in all direction. An isotropic antenna emits energy equally in every direction.
Item-level
A term used to discribed the tagging of individual products, as opposed to case-level and pallet-level tagging.
Label applicator
A device that applies labels to cases or other items. Some label applicators can print bar codes on and encode RFID transponders in labels before applying the labels.
License plate
This term generally applies to a simple RFID that has only a serial number that is associated with information in a database. The Auto-ID Center promoted the concept as a way to simplify the tag and reduce the cost.
Linear-polarized antenna
An antenna that focuses the radio energy from the reader in one orientation or polarity. This increases the read distance possible and can provide greater penetration through dense materials. Tags designed to be used with a linear polarized reader antenna must be aligned with the reader antenna in order to be read. (See circular-polarized antenna.)
Lossy
Characterized by or causing dissipation of energy. For instance, a cable is said to be a lossy cable if the signal attenuates as it travels through the cable.
Low-frequency
From 30 kHz to 300 kHz. Low-frequency tags typical operate at 125 kHz or 134 kHz. The main disadvantages of low-frequency tags are they have to be read from within three feet and the rate of data transfer is slow. But they are less subject to interference than UHF tags.
Memory
The amount of data that can be stored on the microchip in an RFID tag. It can range from 64 bits to 2 kilobytes or more on passive tags.
Memory block
Memory on the microchip in an RFID tag is usually divided into sections, which can be read or written to individually. Some blocks might be locked, so data can't be overwritten, while others are not.
Microcontroller
A complete microprocessor on a chip. A microcontroller includes a central processing unit, RAM or EPROM, clock and control circuits, and serial and parallel I/0 ports.
Microprocessor
The silicon chip that is the heart of a computing system. It includes a central processing unit, internal registers, control logic and bus interfaces to external memory and input-output ports. Some advanced systems also include floating point processors and some memory.
Microwave
A high-frequency electromagnetic wave, one millimeter to one meter in wavelength.
Microwave tags
A term that is sometimes used to refer to RFID tags that operate at 5.8 GHz. They have very high transfer rates and can be read from as far as 30 feet away, but they use a lot of power and are expensive. (Some people refer to any tag that operates above about 415 MHz as a microwave tag.)
Middleware
In the RFID world, this term is generally used to refer to software that resides on a server between readers and enterprise applications. The middleware is used to filter data and pass on only useful information to enterprise applications. Some middleware can also be used to manage readers on a network.
Milliwatt
A unit of power equal to one thousandth of a watt.
MIPS
Million instructions per second
Modulation
Changing the radio waves traveling between the reader and the transponder in ways that enable the transmission of information. Waves can be changed in a variety of ways that can be picked up by the reader and turned into the ones and zeroes of binary code. Waves can be made higher or lower (amplitude modulation) or shifted forward (phase modulation). The frequency can be varied (frequency modulation), or data can be contained in the duration of pulses (pulse-width modulation).
Monostatic
A monostatic RFID interrogator, or reader, uses the same antenna to transmit RF energy to and receive RF energy from the RFID tag.
Multimode
Transponders are called "multimode" when they can be programmed to operate according to several different standards.
Multiple access schemes
Methods of increasing the amount of data that can be transmitted wirelessly within the same frequency spectrum. Some RFID readers use Time Division Multiple Access, or TDMA, meaning they read tags at different times to avoid interfering with one another.
Multiplexer
An electronic device that allows a reader to have more than one antenna. Each antenna scans the field in a preset order. This reduces the number of readers needed to cover a given area, such as a dock door, and prevents the antennas from interfering with one another.
NanoBlock
The term Alien Technology uses to describe its tiny microchips, which are about the width of three human hairs.
National Institute for Standards and Technology
An American standards body that establishes standards for information-processing technology, particularly IT used by the Federal government.
Near-field communication
RFID reader antennas emit electromagnetic radiation (radio waves). If an RFID tag is within full wavelength of the reader, it is sometimes said to be in the "near field" (as with many RFID terms, definitions are not precise). If it is more than the distance of one full wavelength away, it is said to be in the "far field." The near field signal decays as the cube of distance from the antenna, while the far field signal decays as the square of the distance from the antenna. So passive RFID systems that rely on near-field communication (typically low- and high-frequency systems) have a shorter read range than those that use far field communication (UHF and microwave systems)
NFC
See near-field communication
Noise
Unwanted ambient electrical signals or electromagnetic energy found in the operating environment of RFID equipment. Other RF devices, robots, electric motors and other machines can cause noise.
Nominal range
The read range at which the tag can be read reliably.
Non-volatile memory
A generic term for the memory that holds its contents after power has been removed. EPROM, EEPROM and FLASH are examples of non-volatile memory.
Null spot
Area in the reader field that doesn't receive radio waves. This is essentially the reader's blind spot. It is a phenomenon common to UHF systems.
Object Name Service
An Auto-ID Center-designed system for looking up unique Electronic Product Codes and pointing computers to information about the item associated with the code. ONS is similar to the Domain Name Service, which points computers to sites on the Internet.
OEM
See original equipment manufacturer
One-time programmable
Memory that can be written to, or programmed, only once and is afterwards write protected. After the memory is written to, it is like read-only memory.
One-time programmable tag
Also called a field-programmable tag. An RFID tag that can be written to once and read many times (see WORM).
ONS
See Object Name Service
Orientation
The position of a tag antenna vis-à-vis a reader antenna. With UHF systems, readers can be either circular-polarized or linear-polarized. When using a linear polarized antenna, the tag reader and antenna reader must be in alignment in order to achieve the longest reading distance. If that tag antenna is aligned vertically and the reader is sending out signals horizontally, only a small portion of the energy emitted by the reader will hit the tag antenna.
Original equipment manufacturer
A company that builds its own products from components bought from other manufacturers.
Passive tag
An RFID tag without its own power source and transmitter. When radio waves from the reader reach the chip’s antenna, the energy is converted by the antenna into electricity that can power up the microchip in the tag. The tag is able to send back information stored on the chip. Today, simple passive tags cost from U.S. 20 cents to several dollars, depending on the amount of memory on the tag, packaging and other features.
Patch antenna
A term used to describe a square reader antenna made from a solid piece of metal or foil.
Penetration
The ability of a particular radio frequency to pass through non-metallic materials.
Phantom read
When a reader reports the presence of a tag that doesn't exist. This phenomenon is also sometimes called a phantom transaction or false read.
Phase
A part of a complete cycle of a waveform as measured from a specified reference point.
Phase shift keying
A method of communicating data by shifting the waveform's period. Instead of being at the zero axis at a specific point in time, the wave might be shifted forward so that it is at its peak. The reader's digital signal processor might interpret the out of phase signal as a one or zero.
Physical Markup Language
An Auto-ID Center-designed method of describing products in a way computers can understand. PML is based on the widely accepted eXtensible Markup Language used to share data over the Internet in a format all computers can use. The idea is to create a computer language that companies can use to describe products so that computer can search for, say, all "soft drinks" in inventory.
PML
See Physical Markup Language
PML Server
A server that responds to requests for Physical Markup Language (PML) files related to individual Electronic Product Codes. The manufacturer of the item will maintain the PML files and servers. The name PML server has been replaced by EPC Information Service.
Power level
The amount of RF energy radiated from a reader. The higher the power output, the longer the read range, but most governments regulate power levels to avoid interference with other devices.
Printer
An RFID printer, or printer/encoder, is a device that prints a label with an embedded RFID transponder and encodes information in the chip within the transponder.
Printer/encoder
See printer
Private key
A cryptographic key known only to the owner.
Programming a tag
Writing data to an RFID tag. When a serial number is first written to a tag, this is sometimes called "commissioning a tag."
Protocol
A set of rules that govern communications systems. (See Air-interface protocol.)
Proximity sensor
A device that detects the presence of an object and signals another device. Proximity sensors are often used on manufacturing lines to alert robots or routing devices on a conveyor to the presence of an object. They can be used in RFID systems to turn on readers.
Public key
The publicly available and distributed key used in public key cryptography systems.
Public key cryptography
A generic term for all public key algorithms. PKC uses a pair of numeric "keys," one public and one private key. The public key is published and can be used by anyone to either encrypt a message for the owner of the corresponding private key or to verify a signature generated by the owner of the secret key.
Public key infrastructure
A system of storing and distributing public keys together with their current status.
Quiet tag
An RFID tag that can be read only occasionally with the interrogator output at full power, or which can only be read at very close range.
Radio Frequency Identification
A method of identifying unique items using radio waves. Typically, a reader communicates with a tag, which holds digital information in a microchip. But there are chipless forms of RFID tags that use material to reflect back a portion of the radio waves beamed at them.
RAM
See random access memory
Random access memory
Memory used for temporary storage of data. Information stored in RAM is lost when power is removed.
Read
The process of retrieving data stored on an RFID tag by sending radio waves to the tag and converting the waves the tag sends back into data.
Read field
See reader field.
Read range
The distance from which a reader can communicate with a tag. Active tags have a longer read range than passive tags because they use their own power source (usually a battery) to transmit signals to the reader. With passive tags, the read range is influenced by frequency, reader output power, antenna design, and method of powering up the tag. Low-frequency tags use inductive coupling, which requires the tag to be within a few feet of the reader.
Read rate
A term usually used to describe the number of tags that can be read within a given period or the number of times a single tag can be read within a given period. The read rate can also mean the maximum rate at which data can be read from a tag expressed in bits or bytes per second. (See Data transfer rate.)
Read-only
A term used to describe RFID tags that contain data that cannot be changed unless the microchip is reprogrammed electronically.
Read-write
A term used to describe an RFID tag that can store new information on its microchip. These tags are often used on reusable containers and other assets. When the contents of the container are changed, new information is written to the tag.
Reader
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.
Reader field
The area of coverage. Tags outside the reader field do not receive radio waves and can't be read. This is also sometimes referred to as the read field.
Reader module
The electronics of a reader, including a digital signal processor, on a circuit board. Modules can be put in an RFID label printer or other device, as opposed to a standalone reader.
Reader talks first
A means by which a passive UHF reader communicates with tags in its read field. The reader sends energy to the tags but the tags sit idle until the reader requests them to respond. The reader is able to find tags with specific serial numbers by asking all tags with a serial number that starts with either 1 or 0 to respond. If more than one responds, the reader might ask for all tags with a serial number that starts with 01 to respond, and then 010. This is called "walking" a binary tree, or "tree walking." (See singulation.)
Real-time locating system
A system of finding the position of assets, using active RFID tags. The tags broadcast a signal, which is received by three reader antennas. The time each signal is received is passed on to a software system that uses triangulation to calculate the location of the asset. RTLS is used to find containers in a distribution yard, and many automakers use it to track parts bins within a large factory.
Reverse channel
The path through which energy travels from the RFID tag to the interrogator, or reader. It is also sometimes called the back channel.
RFID
See radio frequency identification
RFID Journal
The leading independent publication focused on radio frequency identification and its many business applications.
RFID tag
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. Tags come in many forms, such smart labels that can have a barcode printed on it, or the tag can simply be mounted inside a carton or embedded in plastic. RFID tags can be active, passive or semi-passive.
RTLS
See real-time locating system
Savants
A term used to describe distributed middleware designed by the Auto-ID Center to filter data from EPC readers and pass it on to enterprise systems. It was envisioned that Savants would reside on servers across the EPC Network and pass data to one another and act as a kind of nervous system for the network. The term is being phase out by EPCglobal and many of the functions of Savants are being incorporated in commercial middleware products.
SAW
A technology used for automatic identification in which low power microwave radio frequency signals are converted to ultrasonic acoustic signals by a piezoelectric crystalline material in the transponder. Variations in the reflected signal can be used to provide a unique identity.
Scanner
An electronic device that can send and receive radio waves. When combined with a digital signal processor that turns the waves into bits of information, the scanner is called a reader or interrogator.
Semi-passive tag
Similar to active tags, but the battery is used to run the microchip's circuitry but not to broadcast a signal to the reader. Some semi-passive tags sleep until they are woken up by a signal from the reader, which conserves battery life. Semi-passive tags can cost a dollar or more. These tags are sometimes called battery-assisted tags.
Sensor
A device that responds to a physical stimulus and produces an electronic signal. Sensors are increasingly being combined with RFID tags to detect the presence of a stimulus at an identifiable location.
Signal attenuation
The weakening of RF energy from an RFID tag or reader. The energy emitted by the reader naturally decreases with distance. The rate of decrease is proportional to the inverse square of the distance. Passive UHF RFID tags reflect back a signal at very low power levels. A tag’s reflected signal decreases as the inverse fourth power of the distance between tag and reader. Attenuation can be increased by external factors as well. For instance, water absorbs UHF energy, causing signal attenuation.
Silent Commerce
This term covers all business solutions enabled by tagging, tracking, sensing and other technologies, including RFID, which make everyday objects intelligent and interactive. When combined with continuous and pervasive Internet connectivity, they form a new infrastructure that enables companies to collect data and deliver services without human interaction.
SIM
See subscriber identity module
Singulation
A means by which an RFID reader identifies a tag with a specific serial number from a number of tags in its field. There are different methods of singulation, but the most common is "tree walking", which involves asking all tags with a serial number that starts with either a 1 or 0 to respond. If more than one responds, the reader might ask for all tags with a serial number that starts with 01 to respond, and then 010. It keeps doing this until it finds the tag it is looking for. (See Reader talks first.)
Skimming
Reading an RFID tag on a person without their knowledge or reading a tag surreptitiously.
Slap and ship
A generic term that refers to putting an RFID label on a case or pallet just before it is shipped from a supplier's facility to a retailer's facility. This approach to using RFID is strictly to meet the retailer's requirements and delivers no internal benefits to the supplier.
Slotted antenna
An antenna that consists only of a narrow slot cut into an electrical conductor connected to the transponder. Slotted antennas exhibit the same orientation sensitivity as dipoles.
Smart cards
A credit card or other kind of card with an embedded microchip. When the card uses RFID technology to send and receive data it is called a contactless smart card.
Smart label
A generic term that usually refers to a bar code label that contains an RFID transponder. It's considered "smart" because it can store information, such as a unique serial number, and communicate with a reader.
Smart reader
See intelligent reader
Strap
A type of interposer.
Subscriber identity module
An essential component of a GSM mobile phone. It contains the identity of the subscriber and assures the authentication during the access into the network and provides data storage for other subscriber related information, such as a personal address books.
Substrate
An underlying layer.
Surface acoustic wave
A technology used for automatic identification in which low power microwave radio frequency signals are converted to ultrasonic acoustic signals by a piezoelectric crystalline material in the transponder. Variations in the reflected signal can be used to provide a unique identity.
Synchronization
In RFID, the term refers to timing readers or reader antennas near one another so that they don't interfere with one another.
Tag
See RFID tag
Tag excitation device
A term coined by the RFID Alliance Lab to refer to a device that sends signals to the tag regardless of the make or manufacturer. TED is used to measure the response of tags scientficially.
Tag talks first
A means by which a reader in a passive UHF system identifies tags in the field. When tags enter the reader's field, they immediately communicate their presence by reflecting back a signal. This is useful when you want to know everything that is passing a reader, such as when items are moving quickly on a conveyor. In other cases, the reader wants to simply find specific tags in a field, in which case it wants to broadcast a signal and have only certain tags respond. (See Reader talks first.)
Tamper-evident tag
An RFID tag that communicates to a reader when a package or container has been opened without authorization.
TDMA
See time division multiple access
TED
See tag excitation device
Time division multiple access
A method of solving the problem of the signals of two readers colliding. Algorithms are used to make sure the readers attempt to read tags at different times.
Track and trace
The process of retrieving information about the movement and location of goods.
Transceiver
A device that both transmits and receives radio waves.
Transponder
A radio transmitter-receiver that is activated when it receives a predetermined signal. RFID transponders come in many forms, including smart labels, simple tags, smart cards and keychain fobs. RFID tags are sometimes referred to as transponders.
UCC
See Uniform Code Council
UHF
See ultra-high frequency
UID
See Unique Identification
Ultra-high frequency
From 300 MHz to 3 GHz. Typically, RFID tags that operate between 866 MHz to 960 MHz. They can send information faster and farther than high- and low-frequency tags. But radio waves don’t pass through items with high water content, such as fruit, at these frequencies.
Uniform Code Council
The nonprofit organization that oversees the Universal Product Code, the bar code standard used in North America.
Unique Identification
A numbering scheme used by the U.S. Department of Defense to track high-value items and items, such as chemical suits, that have an expiration date.
Unique identifier
A unique serial number that identifies the transponder.
Universal Product Code
A generic term that refers to the 12 digit data structure encoded in a UCC bar codes.
Universal Serial Bus
An external peripheral interface standard for communication between a computer and external peripherals over an inexpensive cable. Many newer RFID readers can connect to computers via a USB port.
UPC
See Universal Product Code
USB
See Universal Serial Bus
Voltage standing wave ratio
A standing wave may be formed when a wave is transmitted into one end of a transmission line and is reflected from the other end by an impedance mismatch. The Voltage standing wave ratio is the ratio of maximum to minimum voltage in a standing wave pattern. It may be stated as a ratio (VSWR) or in dB (return loss).
VSWR
See voltage standing wave ratio
Wireless Markup Language
WML is a markup language that is based on XML (eXtensible Markup Language). The official WML specification is developed and maintained by the WAP Forum, an industry-wide consortium founded by Nokia, Phone.com, Motorola, and Ericsson. This specification defines the syntax, variables, and elements used in a valid WML file.
WML
See Wireless Markup Language
WORM
See write once, read many
Write once, read many
A tag that can be written to only once by the user. Thereafter, the tag can only be read.
Write range
The distance from which data can be written to an RFID tag.
Write rate
The rate at which information is transferred to a tag, written into the tag's memory and verified as being correct.
X12 EDI
An electronic data interchange schema developed for the American National Standards Institute for inter-industry electronic exchange of business transactions data.
XML
See eXtensible Markup Language
XML Query Language
A method of searching a database based on the extensible markup language (XML). Files created using the Auto-ID Center’s Physical Markup Language can be searched using XQL.
XQL
See XML Query Language


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