equalizer


Also found in: Dictionary, Thesaurus, Idioms, Wikipedia.

equalizer

[′ē·kwə‚līz·ər]
(electronics)
A network designed to compensate for an undesired amplitude-frequency or phase-frequency response of a system or component; usually a combination of coils, capacitors, and resistors. Also known as equalizing circuit.
(mechanical engineering)
A bar to which one attaches a vehicle's whiffletrees to make the pull of draft animals equal. Also known as equalizing bar.
A bar which joins a pair of axle springs on a railway locomotive or car for equalization of weight. Also known as equalizing bar.
A device which distributes braking force among independent brakes of an automotive vehicle. Also known as equalizer brake.
A machine which saws wooden stock to equal lengths.
(ordnance)
A device attached to the carriage of those artillery weapons that, when emplaced, rest on two wheels and two trail ends; it is a compensating mechanism to transmit equally the weapon weight and firing shock.

Equalizer

An electronic filter that modifies the frequency response (amplitude and phase versus frequency) of a system for a specific purpose. Equalizers typically realize a more complicated frequency response in which the amplitude response varies continuously with frequency, amplifying some frequencies and attenuating others. An equalizer may have a response fixed in time or may be automatically and continuously adjusted. However, its frequency response is usually matched to some external physical medium, such as an acoustic path or communication channel, and thus inherently needs to be adjustable.

Equalizers can be used in many applications. In music and sound reproduction, equalizers can compensate for artifacts of the electrical-to-sound conversion or for unwanted characteristics of the acoustic environment such as sound reflections or absorption. Sound-recording and sonar systems can use equalizers to reduce unwanted interference. Most analog recording and playback devices, such as audio and video tape recorders, incorporate equalizers to compensate for the undesirable aspects of the recording medium, such as high-frequency roll-off, as well as to reduce noise and maximize dynamic range.

Equalization is also used to enhance the performance of systems that communicate or record digital signals (streams of bits). All communications and recording systems utilize a physical medium, such as wires; coaxial cables; radio, acoustic, or optical-fiber waveguides; or magnetic and optical recording media. These media cause distortion; that is, the output signal is different from the input signal. For example, on radio or acoustic channels there are often multiple paths from transmitter to receiver, each having a slightly different delay and superimposed at the receiver. An equalizer is an electrical device that compensates for this distortion, reversing the effect of the channel and returning a waveform approximating the input signal. The channel output signal in response to a particular input signal (…,0, 0, 1, 0, 0…) may differ from the input, but the equalizer output reproduces the channel input, at least to close approximation (see illustration). See Distortion (electronic circuits)

Communications channel with an equalizer placed at the outputenlarge picture
Communications channel with an equalizer placed at the output

If the characteristics of the channel are well known, the equalizer can be fixed, or nonadaptive. More commonly, the detailed characteristics of a channel are not known in advance. For example, an equalizer may be required to compensate for any length of wire, from very short up to a maximum. In other cases, the channel may be varying with time, as is characteristic of the radio channel from a fixed transmitter to a moving vehicle. An adaptive equalizer is able to adjust itself to compensate. Adaptive equalizers are important for achieving high bit rates in telephone computer modems, and also for digital communications over radio channels. See Data communications, Modem

References in periodicals archive ?
The Equalizer was designed for short draw archers or those that have had to shoot lower draw weights due to age or injury but has become a favorite with all archers looking to increased performance," Smith says.
4 km) inland from the main shipping channel, making it a strategic location for Equalizer," said Dave Donneral, scrap and material handling equipment manager for CLM Equipment Co.
This forms the simple explanation for Zero Forcing Equalizer with Successive Interference Cancellation (ZF-SIC) approach.
He also starred in the cult film The Wicker Man, and in the 1980s he gained international attention in the hit US TV series The Equalizer.
Currently available nationwide at retailers such as Whole Foods, Albertson's, Hannaford Brothers and Sweet Bay, EQ Thirst Equalizer is available in mango pineapple, lemon lime and tangelo flavors.
The Sound Equalizer under test here was not equipped with this mode and the company avers this is not the optimal mode to use.
The Equalizer solenoid is designed to automatically compensate for heat factors and wiring losses without any reduction in pull force.
The combination of equalizer delivered verbally and add-subtract shown in gestures yielded the highest average scores.
Equalizer technology is ideal for optimizing blade server environments because Equalizer quickly and efficiently routes traffic to the servers with the most available capacity, ensuring the system runs at peak performance levels.
Coyote Point's Equalizer is an intelligent load balancer that provides highly efficient failover, sophisticated traffic routing capabilities, and a browser-based graphical display of server performance that is the best trending analysis tool in the business.
NASDAQ: MSPD), a leading supplier of semiconductor solutions for network infrastructure applications, today introduced an adaptive equalizer with the longest reach and lowest output jitter for serial digital interface (SDI) applications.