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Topic: Equalization filter


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  Equalization filter - Wikipedia, the free encyclopedia
An equalization (EQ) filter is a filter, usually adjustable, chiefly meant to compensate for the unequal frequency response of some other signal processing circuit or system.
A graphic equalizer uses predetermined Q and frequencies which are equally spaced according to the musical intervals, such as the octave (12-band graphic EQ) or one third of an octave (36-band graphic EQ).
Shelving filters, unlike those described above, boost or cut from a determined frequency until they reach a preset level which is applied to the rest of the frequency spectrum.
en.wikipedia.org /wiki/Equalization_filter   (683 words)

  
 Active Filters
The equalizer frequency response is shown below, correcting for a woofer with peaked response (Qp = 1.21) and early roll-off (Fp = 55 Hz), to obtain a response that is 6 dB down at 19 Hz and with Q = 0.5.
The equalizer action is difficult to visualize in the time domain, because the driver output waveform is the convolution of the input signal s(t) with the impulse response of the equalizer h
The equalizer output signal is convolved with the impulse response h
www.linkwitzlab.com /filters.htm   (2352 words)

  
 equalization   (Site not responding. Last check: 2007-10-25)
The term "equalizer" is sometimes applied to audio filters in general, though strictly speaking not all audio filters are equalizers.
One common type of equalizer is a graphic equalizer, which consists of a bank of band-pass filters, with an independent gain control for each band.
An equalizer is used to ensure that there are no frequency bands where there is a round trip gain of greater than 1, as these are heard as audible feedback.
en.mcfly.org /equalization   (418 words)

  
 [No title]   (Site not responding. Last check: 2007-10-25)
The filter coefficients of the adaptive channel equalization filter are commonly initialized by the training signal method, using a training signal extracted from the data field synchronizing (DFS) signals in the initial data segments of data fields.
The objective of the invention is to avoid the initialization of the filter coefficients of the adaptive channel equalization filter in response to training signal being affected by artifacts of co-channel NTSC interference that accompany the DFS signals.
An adaptive channel equalization filter provided with adjustable filtering coefficients is included in the cascade filter connection together with a comb filter for suppressing the demodulation artifacts of interference from a co-channel analog television signal.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=99/16240.990401&ELEMENT_SET=DECL   (10272 words)

  
 Automatic time domain equalization of audio signals - Patent 4458362
More precisely, an equalizer is a device which alters the transfer function of one part of a system to compensate for errors in the transfer function of another part of that system; although the parts of the system may have non-uniform individual transfer functions, the overall performance of the system is thus improved.
The output of filter 40 is connected to amplitude equalizer circuit 42, the latter serving to correct the rolloff introduced by converter 38.
To achieve the desired filter, a first step prior to execution of the initial convolution is the insertion, as part of the system impulse response, of an ordinal zeroth coefficient with an assigned value which results in a corresponding zeroth coefficient of unit cardinal value in the filter derived by this method.
www.freepatentsonline.com /4458362.html   (10552 words)

  
 Equalization filter: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-10-25)
A graphic equalizer uses predetermined Q and frequencies which are equally spaced according to the musical intervals, EHandler: no quick summary.
In audio processing, equalization (eq) is the process of modifying the frequency envelope of a sound....
An audio filter is a type of filter used for processing sound signals....
www.absoluteastronomy.com /encyclopedia/e/eq/equalization_filter.htm   (1210 words)

  
 ACEi - Automated Controlled Environments inc.
This allows for a specific filter, in terms of center frequency (fc), attenuation level (gain), and filter order (Q), that is accurately tailored to eliminate the primary room resonance of the listening environment.
Equalization proponents’ debate if attenuating only one listening environment room resonance is sufficient to address the problems of the listening environment.
Equalizing the listening environment based on an un-calibrated and weighted meter, or microphone, will more often than not result in a frequency response that is worse than what was started with.
www.acei-ca.com /description.htm   (931 words)

  
 Equalization Signal Processing
Equalization is the increase or decrease of signal strength for a portion of (a band of) audio frequencies.
Thus equalization effects the tone because it changes the level relationship of the fundamental and harmonic frequencies.
Filter with this as a HPF cutoff frequency to reduce leakage into lead instruments such as lead guitars and for female vocals.
www.recordinginstitute.com /da154/ARP/chap3Sig/asp3.html   (2424 words)

  
 [No title]   (Site not responding. Last check: 2007-10-25)
In the illustrative embodiment, the inventive filter is adapted for use with a multi-carrier wireless CDMA system and includes a first mechanism for receiving the multi-carrier signal and extracting constituent carrier signal components in response thereto.
The outputs of the filtering circuits are then multiplied by carrier signals that differ in phase to yield a center carrier signal, a right carrier signal, and a left carrier signal which are then added together and transmitted over a wireless channel.
Consequently, in the first mode, a 3x DS pre- equalization filter (not shown) similar to that employed by the transmitting base station (not shown) is included after the 3x DS pre-equalization compensation circuit 74 to undue unnecessary 3x DS pre-equalization compensation.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=02/60114.020801&ELEMENT_SET=DECL   (8664 words)

  
 Loudspeaker Equalizer - Bass Circuit   (Site not responding. Last check: 2007-10-25)
There are a number of possible means that might be used to implement the equalization filter described on the previous page.
An entirely workable analog solution would be to use a state variable or "biquad" filter.
Since the bass equalizer requires complex poles and zeros, we will use 2nd order networks for both input and feedback.
home.att.net /~wjlservo/spkreq3.html   (597 words)

  
 mEQ Equalization System   (Site not responding. Last check: 2007-10-25)
After compression some degree of equalization may be needed to compensate for the shift in spectral balance caused by compression, or worse still, to compensate for a poor mix-down.
The filter in mEQ is an 8192 point linear phase FIR filter whose characteristics are designed to match and compensate for the average spectrum as closely as possible.
If after listening to the result we are satisfied with the filter we can equalize the source and record it to a new wave file using the record button.
www.taquis.com /meq.htm   (1456 words)

  
 Histogram Equalization Filter for VirtualDub   (Site not responding. Last check: 2007-10-25)
This filter applies a global color histogram equalization on a per-frame basis.
The filter redistributes the pixel intensities to equalize their distribution across the intensity range.
This filter is useful only for correcting degraded or poorly captured source video.
www.neuron2.net /histogram.html   (513 words)

  
 OTL - File # 3300
The equalization is performed simultaneously for multiple listeners in any environment (e.g., rooms, automobiles, theatres, etc.) The method obtains a filter by: (i) measuring the room acoustical responses at multiple seating positions, and (ii) applying the measured responses to a pattern recognition algorithm for computing the desired filter.
The invention obtains a filter through an intelligent algorithm for equalizing the acoustical characteristics of rooms at several locations simultaneously.
The filter, once determined, does not need to be recomputed unless significant changes occur in the environment.
www.usc.edu /academe/otl/3300.htm   (180 words)

  
 Comb filter equalization circuit (US4263612)
A comb filter apparatus is provided with means for equalizing the delayed and undelayed signal levels at the inputs to the adding or subtracting matrix, whereby maximum cancellation and reinforcement of the undesired and desired signals is effected.
The delayed and undelayed signals at the inputs to the matrix are each coupled to a detector by way of a bandpass filter, which pass frequencies at which the combing of the signal is most critical.
The gain control signal is utilized to control the gain of a gain controllable stage which is coupled in series with one of the signal paths thereby equalizing the levels of the input signals to the combining matrix.
www.delphion.com /details?pn=US04263612__   (472 words)

  
 [No title]   (Site not responding. Last check: 2007-10-25)
For example, analog filters can be converted to digital using such methods as the bilinear transform or the impulse invariant method.
Since this is a first-order filter, the b2 and a2 coefficients are zero if implementing in a second-order section.
One of the most commonly encountered second-order IIR filters is the bell-shaped parametric equalization filter.
www.planetanalog.com /showArticle.jhtml?articleID=12802683&pgno=2   (578 words)

  
 USC-SIPI REPORT #202   (Site not responding. Last check: 2007-10-25)
This tutorial paper is focused on two topics, namely: (i) to describe systematic methodologies for selecting nonlinear transformations for blind equalization algorithms (and thus new types of cumulants), and (ii) to give an overview of the existing blind equalization algorithms and point out their strengths as well as weaknesses.
We also show that blind equalizers based on nonlinear filters or neural networks are more suited for channels that have nonlinear distortions.
We present a new method for blind equalization, the CRIMNO algorithm (i.e., criterion with memory nonlinearity), which is shown to have the same advantages as Godard (simplicity, low complexity, constant modulus property) and yet guaranteeing much faster convergence.
sipi.usc.edu /reports/abstracts/usc-sipi.202.html   (246 words)

  
 Har-Bal Product Information
When you perform EQ on a typical equalizer or mixing desk you cannot make an impartial judgment about whether a particular EQ setting is good or not because it is generally not loudness compensated.
After compression some degree of equalization may be needed to compensate for the shift in spectral balance that compression often causes, or worse still, to compensate for a poor mix-down.
Har-Bal, on the other hand, uses an 8192 point linear phase FIR filter whose characteristics are designed to match and compensate for the average spectrum as closely as possible and the degree to which you can boost and cut a particular region is essentially unlimited.
www.har-bal.com /product_info.php   (1469 words)

  
 Dark Frame Subtraction   (Site not responding. Last check: 2007-10-25)
In addition, even on the most expensive lens and camera systems, most lenses do not pass an equal amount of light in the center of the image when compared to the edges.
Frame equalization allows you to completely remove these effects by using a single test shot to remove any color/brightness bias across the image.
The corners may be slightly darker than the center, etc. When you use the frame equalization filter, Qimage will use this reference frame to "reverse" the bias in the image to produce a smooth, evenly lit scene.
www.ddisoftware.com /qimage/qimagehlp/dark.htm   (758 words)

  
 Title page for ETD etd-051205-101321   (Site not responding. Last check: 2007-10-25)
In general, the spatial filtering is implemented in hardware and the performance of the spatial filtering apparatus is measured by its common mode rejection ratio (CMRR).
In this project, a distinct software equalization filter was cascaded with each of the hardware monopolar signal conditioning circuits to achieve accurate weighting and high CMRR.
The simplest technique we explored was to design an equalization filter by dividing the frequency response of a “reference” (or “ideal”) channel by the measured frequency response of the channel being equalized, producing the desired equalization filter in the frequency domain (conventional technique).
www.wpi.edu /Pubs/ETD/Available/etd-051205-101321   (305 words)

  
 Equalization filter   (Site not responding. Last check: 2007-10-25)
Zverev is the classic reference for continuous time filter design, especially lumped element LC ladder filters.
The book is mostly tables, but the plots of filter behaviour for different designs--ripple, group delay, and so on, are easily worth the price....
Because many filters readers not understand this book, I recommend, for a good understand, to work with synthesis software like one at www.filterscad.com...
www.freeglossary.com /Equalization_filter   (369 words)

  
 Windowed Histogram Equalization Filter for VirtualDub   (Site not responding. Last check: 2007-10-25)
A global histogram equalization (as performed by the sister filter Histogram Equalization) is useful for many but not all images.
Note that the filter requires these values to be factors of the image dimensions.
Version 1.0 beta 3 fixed a bug in script support (you needed to move the strength slider to "wake up" the filter), and is recompiled as a multithreaded DLL to reduce the executable size.
neuron2.net /winhistogram.html   (502 words)

  
 Green Building Encyclopedia - Glossary of Green Building Terms
One candela equals one lumen per steradian—a specific measure of luminous intensity, in a given direction.
In general terms, a means of defining the relative whiteness of a light source, specifically the absolute temperature (degrees Kelvin) of a flbody radiator having a chromaticity equal to that of the light source.
A method of constructing walls in which the cladding is separated from a membrane by an airspace that allows pressure equalization to prevent rain from being forced in.
www.whygreenbuildings.com /glossary.php   (6282 words)

  
 Histogram Equalization   (Site not responding. Last check: 2007-10-25)
Histogram equalization of CT images -- Lehr and Capek 154 (1): 163 -- Radiology...
Adaptive histogram equalization in digital radiography of destructive skeletal l...
IngentaConnect Histogram equalization of vibration fringes in holography...
www.scienceoxygen.com /signal/74.html   (207 words)

  
 RetouchPRO - Free Plug-In Filters: Custom Filter & Adaptive Equalization
The Custom Convolution Filter is like Photoshop's filter/other/custom with floating point precision (as if convolution needs to be made harder with more precision than simple integer math) and a few other options including high bit edit ability.
Before using this filter, it might be wise to use methods similar to ones described in a small article of mine (Photoshop 5 action included to help demonstrate the methods in the article):
Next time we’ll do a High Pass filter which is basically subtracting the blurred image from the original, show how that is related to the UnSharp Mask (and where the USM came from) and we’ll go from there.
www.retouchpro.com /forums/showthread.php?t=4015   (2639 words)

  
 A new way to monitor DTV transmission line
It uses the multipath-cancelling reference signal transmitted from the DTV station’s antenna, along with the adaptive-equalization filter in a demodulator, to estimate the location of anomalies on the station’s transmission line.
Because the equalizer filter corrects for pre and post echoes, its tap values are a measure of the echoes (VSWR discontinuities) in both time directions.
Since the equalizer locks onto the largest signal, this forward insertion level protects the equalizer lock by desensitizing the downstream signals.
broadcastengineering.com /features/monitor-dtv-transmission   (1870 words)

  
 Products   (Site not responding. Last check: 2007-10-25)
Many different box types are supported, including: closed boxes, vented boxes, vented boxes with an external active 2nd-order high-pass equalization filter (B6), single-tuned and double-tuned bandpass boxes with two or three chambers, and passive radiator boxes.
Many different speaker box types are supported, including: closed boxes, vented boxes, vented boxes with an external active 2nd-order high-pass equalization filter (B6), single-tuned and double-tuned bandpass boxes with two or three chambers, and passive radiator boxes.
A variety of 1st, 2nd, 3rd and 4th-order filter types are available.
www.ht-audio.com /products.htm   (1094 words)

  
 Gain Equalization (or Flattening) Filters
The terms "gain equalization" and "gain flattening" come from the fiberoptic telecommunications field, where erbium-doped fibers are used to amplify the light traveling through the fiber.
For example, for visible wavelengths 380-780 nm, a filter could be constructed to convert any continuous-spectrum illuminant into white light; e.g., light from an ordinary light bulb could be filtered to produce almost pure white light.
Numerical experiments show that, in general, merely designing a filter that is flatter where the EDFA intensity is high will still be very sensitive to thickness variations.
www.sspectra.com /designs/gainflat.html   (846 words)

  
 Acoustics Research
The methods will be compared and the equalized sound fields using both methods will be compared with the equalized sound fields using a spatially averaged pressure inverse filter and an inverse filter built from a single pressure measurement.
The paper discussesthe implementation of the equalization system in a one-dimensional duct.An adaptive algorithm is utilized in the time domain todetermine and apply the equalization filter.
An optimum equalization scheme is thensuggested that is based on the spatially averaged mean-square pressureof the field.
www.physics.byu.edu /research/acoustics/research.aspx   (4240 words)

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