Radio Frequency Identification (RFID): Definitions
(some of the of terms used in RFID technology)
2. The extraction, decoding, and presentation of data from a tag.
Active tags have a longer read range than passive tags because they use 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.
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.
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.
3. A device that extracts and separates the information from the tag.
Tags outside the reader field do not receive radio waves and can't be read.
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 for additional relevant information.
2. Tags that can only be read because they were programmed at the factory.
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. Read-write tags are more expensive than read-only tags.
Information can be added or changed.
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.
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 phased out by EPC Global and many of the functions of Savants are being incorporated in commercial middleware products.
When combined with a digital signal processor that turns the waves into bits of information, the scanner is called a "reader" or "interrogator".
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.