The number of repetitions of a complete wave within one second.

One Hz equals one complete waveform in one second. One KHz 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.

A sound frequency between 20 and 20,000 cycles per second, or hertz: Audio frequency refers to the frequency of oscillation able to be detected by the ear of a human.

Audio-frequencies are those of electrical, sound, or other wave vibrations coming within the range of normal human hearing.

Any of various instruments used to measure the frequencies of sound waves that are audible to the human ear: Linda learned in her engineering class that one type of audio-frequency meters was a resonant-reed frequency meter.

The portion of the acoustic energy spectrum: The audio-frequency range is from about 20 to 20,000 vibrations per second, or that which can be detected by a human with normal hearing:

The percentage of nights on which an aurora is seen at a given location or place on earth, or on which one would be seen if clouds don't interfere.

The main frequency of a transmitter, or RFID reader; such as, 915 MHz. The frequency is then changed, or modulated, to transmit information.

1. A circuit that passes selected frequencies of alternating currents while weakening other frequencies.
2. A network that transmits alternating currents of desired frequencies while substantially attenuating all other frequencies.

A meter that uses the resonant properties of mechanical devices to indicate frequency.

An instrument that generates two or more selectable frequencies from one or more fixed-frequency sources.

1. A fuse that is ignited by a self-contained electronic element; for example, a proximity fuse or an electronically triggered device designed to detonate an explosive charge in a missile, etc., at a predetermined distance from the target.
2. A fuse; such as, the radio proximity fuse, set off by an electronic device incorporated within it.

A fuse that detonates a warhead when the target is within some specified region near the fuse.

Radio, radar, photoelectric, or other devices may be used as activating elements.

1. Heating which is generated by a radio-frequency power source, that produces a radio-frequency current.
2. Heating with radio-frequency current that is produced by an electron-tube oscillator or an equivalent radio-frequency power source.
3. A method of heating a material by inducing a high-frequency current into it or having the material act as the dielectric (having little or no ability to conduct electricity) between two plates charged with a high-frequency current.

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.

1. The instantaneous variation of the frequency of a carrier wave in response to changes in the amplitude of a modulating signal, which provides a more static-free transmission of radio waves than AM (amplitude modulation) broadcasting.
2. Variation of the frequency of a carrier wave (commonly a radio wave) in accordance with variations in the audio signal being sent.

Developed by American electrical engineer Edwin H. Armstrong in the early 1930's, FM is less susceptible to outside interference and noise; such as, thunderstorms, nearby machinery, etc. than is AM.

Such noise generally affects the amplitude of a radio wave but not its frequency, so an FM signal remains virtually unchanged.

FM is also better able to transmit sounds in stereo than AM and commercial FM broadcasting stations transmit their signals in the frequency range of 88 megahertz (MHz) to 108 MHz.

1. From three MHz to 30 MHz. HF RFID tags typically operate at 13.56 MHz. 2. Tags that operate between three and 30 MHz.

1. From 30 kHz to 300 kHz. 2. Tags that operate at a frequency as low as 30 KHz or as high as 300 KHz, but most often at 125 KHz.

In the United States, a collection of radio frequencies that are used for communication between ships, or between ships and coastal stations: MARISAT uses the maritime frequency bands to make communication easier within the navigation system.

Tags that operate at a frequency of 300 KHz to three MHz.

NATO expanding current usage of RFID.

Blocking readers from RFID data.

China doesn't use RFID because it considered too expensive and it is too difficult to set it up.

RFID is ready for more and more commercial applications.

Glossary of terms used in RFID technology.

RFID Index.

Bill is proposed in New Hampshire, U.S., to place limits on RFID applications.

An explanation of what RFID is.

1. A method of identifying unique items using radio waves. 2. A system that reads or writes data to RF tags that provide identification and other information pertaining to the object to which the tag is attached.

A system that communicates over a radio link between a data source and a scanner or reader.

When used in the context of theft detection systems, it refers to a system that uses tags that can only be turned on and off.

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.

1. A device that converts an analogue input voltage into a sequence of digital pulses with a frequency that is proportional to the input voltage.
2. A converter that has an output frequency which is a function of some reference or control signal.

This digital output can be fed into a computer for a process control or for other applications.