Radio Frequency Identification (RFID): Definitions

(some of the of terms used in RFID technology)

sensor (s) (noun), sensors (pl)
1. A tool or a device that responds to a physical stimulus and produces an electronic signal: Sensors are increasingly being combined with RFID tags (Radio Frequency Identification tags) to detect the presence of a stimulus at an identifiable commercial location by using radio waves.

Some libraries use sensors at their exits in order to make sure that no one is taking materials away without making proper check outs.

2. Any detection instrument that is used to determine temperature, moisture, radiation, light, distance, or motion: There are all kinds of sensors which are being utilized to gain information that is essential for the well-being of humanity.
signal attenuation
The weakening of RF energy from an RFID tag or reader.

Water absorbs UHF energy, causing signal attenuation.

silent commerce (s) (noun), silent commerces (pl)
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, silent commerce forms a new infrastructure that enables companies to collect data and deliver services without human interaction.
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.

smart cards
In the context of library RFID systems, a patron card that has an RFID chip in it.
smart label
A generic term that usually refers to a barcode label that contains an RFID transponder.

It's considered "smart" because it can store information; such as, a unique serial number and it can communicate with a reader.

surface acoustic wave, SAW (s) (noun); surface acoustic waves; SAWs (pl)
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: Surface acoustic waves were first described by Lord Rayleigh in 1885.

Variations in the reflected signal can be used to provide a unique identity.

SAW appliances are applied in television and radio.
synchronization (s) (noun), synchronizations (pl)
The relation that is present when things happen at the same time; synchronism: The leader said that the synchronization of the hikers watches was of utmost importance.

With precise synchronisation the boys jumped into the swimming pool.

The transponder or electronic label that contains the information identifying an object.
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.

A term that encompasses magnetic strips, RF tags, and RFID tags.
time division multiple access, TDMA
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.

A device that both transmits and receives radio waves.
transponder (s) (noun), transponders (pl)
A radio transmitter-receiver that is activated when it receives a predetermined signal: RFID (Radio Frequency Identification) transponders come in many forms, including smart labels, simple tags, smart cards and keychain fobs.

Injectable ID chip or biochip transponders

Biochip transponders are electronic devices that are inserted under the skin of an animal to provide it with a unique identification number.

Injectable ID transponders are less painful, faster to implement, and more cost-effective than ear-tags, brands, or tattoos, have been used to identify livestock animals; such as, pigs, sheep, cows, and horses for several years.

Once inserted under an animal's skin the transponder remains inactive until read by a compatible scanner.

The scanner works by sending a low frequency radio signal to "wake up" the transponder and provide it with the power it needs to send its unique identification code back to the scanner where it is read, compared to other codes in the database so it can positively identify each animal.

Here is a List of Radio Frequency Identification articles for further explanations: RFID

ultra-high frequency, UHF
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-frequency and low-frequency tags, but radio waves don’t pass through items with high water content; such as, fruit, at these frequencies.

UHF tags are also more expensive than low-frequency tags, and they use more power.

List of Radio Frequency Identification or RFID articles.