E-N

Electronic product code (EPC)

A family of coding schemes for Gen 2 tags. The EPC is designed to meet the needs of various industries, while guaranteeing uniqueness for all EPC-compliant tags.

Electrostatic discharge (ESD)

The rapid release of a charge that has accumulated on a person or object. Most materials can be electrically charged by friction; the charge is highly dependent on the material, speed of contact and separation, and the environmental humidity.

Filter value

Used for fast filtering and preselection of defined logistic types.

Frequency hopping

A method of switching channels when operating in dense reader mode.

Frequency-division multiplexing

The division of the frequency spectrum into multiple channels, so each reader can have its own channel to operate on.

General manager number

A number that identifies the organizational entity or company. This number is assigned by EPCglobal and is unique for each entity.

Header

Part of the EPC number that carries the information about the encoding scheme used; this determines the type, length, and structure of the EPC. The header is followed by the unique EPC identifier and a filter value. EPC supports several encoding schemes.

High frequency (HF)

13.56 MHz, the globally accepted and implemented frequency at which HF tags operate.

Inductive coupling

A process where the tag knows it is going to be in the magnetic field of the reader and is ready to respond appropriately.

Light stack

A single tube with red, green, and yellow lights in it. Light stacks are often used to indicate whether the tag applied to the product or packaging functions (green for a read, red for no-read). Light stacks are used with an interrogation zone, where the tag's function is verified and the appropriate light indicates the result. There are several ways to make this work.

Linearity

A property of electromagnetic waves. Linear waves do not affect the passage of other waves as they intersect. Thus, the total of two linear waves at their intersection is simply the sum of the two waves as they would exist separately.

Listen-before-talk (LBT)

A method of communication used with the frequency-division multiplexing scheme. The reader has to listen for any other reader transmitting on the chosen channel; only after it determines that the channel is available can it start using this channel for communication. If the channel is being used by another reader, the listening reader has to switch to another channel. This technique is mainly required in Europe by regulatory agencies.

Low frequency (LF)

A frequency from 125 kHz to 134 kHz, which is the frequency at which LF tags operate.

Microwave frequency

Frequencies around 2.45 GHz and sometimes 5.8 GHz. Because of the frequency properties, microwave tags have the highest data-transfer rates of all tags, but the worst performance around liquids and metals.

Miller subcarrier

A method of encoding that is slower but less susceptible to interference because of an advanced filtering technique that helps separate the tag responses from the signal transmitted by the reader. This method fits the tag responses between the channels used by the readers. It also guards the readers to prevent them from crossing into the tag channels.

Mono-static antenna

An antenna that fulfills both transmitting and receiving functions.

Multi-path interference

Caused by reflections of an RF signal interfering with the antenna's field. When the reflected wave crosses the transmitted wave, it causes either null points with no signal, or spots with a high signal concentration.

near field

The electrostatic field of an electric charge and the magnetostatic field of a current loop.

near-field region

The distance found by applying the Complete Laws to magnetic dipoles by using the formula r = λ/(2π).