Word Entries containing the term:
audio frequency range, audio range
The portion of the acoustic energy spectrum, from about 20 to 20,000 vibrations per second, that can be detected by a human with normal hearing.
audio frequency, audio-frequency, audiofrequency
1. Sound frequency between 20 and 20,000 cycles per second, or hertz; such as, the frequency of normally audible sound waves.
2. A frequency 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.
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.
electric filter, electric wave filter, frequency selective device, frequency-selective device
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.
electromechanical frequency meter
A meter that uses the resonant properties of mechanical devices to indicate frequency.
electronic frequency synthesizer
An instrument that generates two or more selectable frequencies from one or more fixed-frequency sources.
electronic fuse, radio-frequency heating, influence fuse, variable-time fuse, vt fuse
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.
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electro-, electr-, electri-
fluct-, flucti-, -flux, flu-, flum-, -fluent, -fluence
-tron, -tronic, -tronics +
electronic heating, high-frequency heating, radio-frequency heating or RF heating
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.
frequency modulation, FM (s) (noun)
, frequency modulations (PL)
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.
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1. From three MHz to 30 MHz. HF RFID tags typically operate at 13.56 MHz.
They typically can be read from less than three feet away and transmit data faster than low-frequency tags, but they consume more power than low-frequency tags.
2. Tags that operate between three and 30 MHz.
The frequency used in library RFID systems is 13.56 MHz. ISO 18000-3 addresses the air interface for tags operating in this frequency range.
These tags can be read at up to a distance of ten feet and have a fast data transfer rate.
1. From 30 kHz to 300 kHz.
Low-frequency tags typical operate at 125 kHz or 134 kHz. The main disadvantages of low-frequency tags are they have to be read from within three feet and the rate of data transfer is slow.
They are less subject to interference than UHF tags.
2. Tags that operate at a frequency as low as 30 KHz or as high as 300 KHz, but most often at 125 KHz.
They can be read at no more than three feet and the data transfer rate is slow. This type of tag is widely used in retailing because it is relatively inexpensive.
maritime frequency bands
In the United States, a collection of radio frequencies that are used for communication between ships, or between ships and coastal stations.
Tags that operate at a frequency of 300 KHz to three MHz.
Radio Frequency Identification (RFID): NATO
NATO expanding current usage of RFID
Radio Frequency Identification (RFID): Blocking Reader Scans with Foil
Blocking readers from RFID
Radio Frequency Identification (RFID): China Resisting Use
China doesn't use RFID
because it considered too expensive and it is too difficult to set it up.
Radio Frequency Identification (RFID): Commercial Applications
is ready for more and more commercial applications.
Radio Frequency Identification (RFID): Definitions
Radio Frequency Identification (RFID): Index of Units
Radio Frequency Identification (RFID): State Government Restrictions
Bill is proposed in New Hampshire, U.S., to place limits on
Radio Frequency Identification (RFID): What is RFID?
An explanation of what RFID
radio frequency identification, RFID
1. A method of identifying unique items using radio waves.
Typically, a reader communicates with a tag, that holds digital information in a microchip; however, there are chipless forms of RFID tags that use material to reflect back a portion of the radio waves beamed at them.
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.
The tags have storage capacity for at least an identification number.
radio frequency, RF
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.
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.
voltage-to-frequency converter, V/F converter
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.
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