Glossary Of Rfid Terms -- A

Accelerometer

A device that measures acceleration (the rate of change of velocity). An accelerometer inherently measures its own motion (locomotion), as opposed to a device based on remote sensing.

Active

When used to refer to an RFID transponder, the term "active" means a transponder has a power source. This is usually a battery, but energy can also be captured from light via photovoltaic cells or other sources. An active tag can, therefore, broadcast its own signal, like a cell phone. Because an active tag has its own source of power to broadcast a signal, it has a longer read range than most passive tags.

Active tag

An RFID transponder that has its own power source, which enables it to broadcast a signal.

Addressability

The ability to write data to different fields, or blocks of memory, in the microchip in an RFID transponder.

Advance shipping notice

An electronic document that is sent to a trading partner, so the partner knows what goods have been shipped. These documents are typically sent via electronic data interchange (EDI).

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.

API

A source-code interface provided by a computer system or program library to support a computer program's requests for services. Unlike an application binary interface, an API is specified in terms of a programming language that can be compiled when an application is built, rather than an explicit low-level description of how data is laid out in memory.

Applet

A software component designed to run in the context of another program, such as a Web browser.

Application family identifier

An International Organization for Standardization (ISO) method for classifying radio frequency identification by application, enabling a single air interface protocol to be used across several applications.

Application Level Events

An EPCglobal standard that defines interfaces through which clients may interact with filtered, consolidated EPC data and related data from a variety of sources. The role of the ALE interface within the EPCglobal Architecture Framework is to provide independence between the infrastructure components that acquire the raw EPC data, the architectural component(s) that filter & count that data, and the applications that use the data.

Application Programming Interface

A source-code interface provided by a computer system or program library to support a computer program's requests for services. Unlike an application binary interface, an API is specified in terms of a programming language that can be compiled when an application is built, rather than an explicit low-level description of how data is laid out in memory.

Application-Specific Integrated Circuit (ASIC)

An integrated circuit (IC) customized for a particular use (such as a chip designed solely to run a cell phone) rather than general use.

Applicator

A label-printing device that automatically prints and applies pressure-sensitive labels to various products. Such labels can be used for shipping, content, graphic images or complying with specific standards, such as UPC or GS1. A pressure-sensitive label consists of a label substrate and an adhesive.

ASIC

An integrated circuit (IC) customized for a particular use (such as a chip designed solely to run a cell phone) rather than general use.

Asset Tracking

One of the most common applications for RFID. Placing RFID transponders on or in high-value assets and returnable transport containers enables companies to gather data on their location quickly and with little or no manual intervention. Tagging assets allows companies to increase asset utilization, identify the last known user of assets, automate maintenance routines and reduce lost items.

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 as 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. The Auto-ID Labs are the successors to the Auto-ID Center.

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.