Questions tagged [equalization]

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Equalize Speaker using Frequency Response Curve

I have a speaker for which I know the frequency response curve (-5dB at 600Hz, -3dB at 700Hz, ... +5dB at 10kHz). This response curve is not as flat as I would like, and so I want to write a script ...
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1answer
317 views

Why do the OFDM training (and payload) symbols have silent sub-carriers (aka virtual carriers)?

I am examining an OFDM signal. Training symbol: The first two OFDM symbols are training symbols, they are 2PSK modulated (within the subcarriers). In the first OFDM symbol the $(0+18N)^{\rm th}$ ...
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2answers
108 views

MP3 equalization

I made an equalizer using eq10q filters. Now I want to use my equalizer for music equalization and make my own music player. So I have some doubts: If I want to equalize MP3 files, do I have to ...
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1answer
2k views

importance of using histogram equalization

I'm reading opencv tutorials and I'm diving into histogram equalization. i have looked in wikipedia, there is a nice example that sums up exactly the problem: original: equalized: but for getting ...
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1answer
109 views

Histogram Equalization

I am reading the etext on Digital Image Processing by Gonzalez and under the section on Histogram Equalization, an equation which is apparently basic is shown. I have no clue what the equation means ...
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1answer
783 views

Matlab: What should be the BER performance for BPSK using Constant Modulus Algorithm equalizer

I need help in plotting the Bit error curve or the symbol error curve for BPSK modulation scheme for varying Signal to Noise ratios or Eb/N0. The plot should show the simulated versus the theoretical ...
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1answer
932 views

Given an FIR filter coefficients, how can I find coefficients of its equalizer filter?

I have an N-tap direct form complex FIR filter with known coefficients [c0 c1 .. cn]. I want to find the coefficients of its equalizer filter which when cascaded ...
4
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1answer
3k views

Design of equalizer for wireless communication

I am having difficulty in trying to understand the working mechanism of an equalizer. Please correct me where wrong. Mechanism of an Equalizer - The purpose of an equalizer is to reduce intersymbol ...
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1answer
188 views

Equalization knowing the Channel State Information

I am trying to simulate a simple communication system using channel estimation. I was able to estimate the channel response using the Least Squares channel estimator, and it is working properly (...
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2answers
3k views

Which filter for an audio equalizer

I’m new to DSP and I have to do an audio equalizer in c++. I did a lot of research about it and tried some stuff in the last month, but I’m a little overwhelmed with all those informations and it’s ...
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1answer
179 views

Help in deriving the update rule for equalizer

Considering an FIR system excited by an input $s_n$. If the input is derived from a mapping, and a +1/-1 BPSK signal is derived. Considering the Constant Modulus Algorithm (CMA). The channel is ...
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3answers
1k views

Why histogram equalization fail in enhance images for bimodal histogram?

I'm on histogram equalization process. I have quite well understood the math but i don't understand why an histogram on bimodal image fails in image enhancement and what techniques can be used in this ...
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0answers
134 views

Fractional equalizer with non-integer oversampled signal as input

I would like to know how the output sequence from a fractionally spaced equalizer, with a non-integer oversampled input signal, is generated. For example, for $T=T_{sym}/2$, my actual code is ...
3
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1answer
265 views

Does the OFDM MMSE Channel Estimator Require Prior Channel Knowledge?

The OFDM MMSE channel estimator seems to require a-priori knowledge of the channel to calculate the MMSE estimate. See equation 8 here: http://cache.freescale.com/files/dsp/doc/app_note/AN3059.pdf. ...
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1answer
399 views

Strange Results from Biquad Peaking EQ Filter

I have a signal that I am filtering on an MCU (STM32F405) that I get from a codec (CS42L52). It is being sampled at a sampling frequency of 48kHz (actually between 48400 and 48600). I have a ping ...
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1answer
89 views

Quantizing a filtered signal

In the process of trying to learn dialup, I've managed to learn/figure out everything except how to convert a demodulated/filtered signal back into the original data. Here I have a random two-bit ...
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2answers
1k views

Manipulating with frequencies through fftw

I'm using portaudio for I/O audio streaming, and I wanted to apply some equalization on audio input from microphone. I found that most people refer to fft for task like that, so I use FFTW library in ...
2
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1answer
177 views

Transmit diversity vs multi-path?

Are transmit diversity signal and the multi-path signal same? Multi-path contains LOS+delayed and attenuated/distorted versions of it and transmit diversity signal contains LOS1+delayed LOS2+ +delayed ...
2
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0answers
141 views

TDE, OFDE and FDE equalizer simplest exmple in matlab

I want to implement the equalizer in matlab. I am just learning this. I want a good kick start code that can help me to learn it further. I searched a lot on Google but do not find a good reference ...
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2answers
135 views

glitches when performing EQ on an OLA FFT

i'm trying to filter a signal with a FFT. I window each block of signal (i use a 4096 points signal) and then remove some high frequencies by just multiplying the magnitude response. the result is : ...
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4answers
7k views

Why is histogram equalization called as “equalization”?

When output histogram is not same as reference histogram, why is the method called histogram equalization? For example below are two figures from http://en.wikipedia.org/wiki/Histogram_equalization. ...
3
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1answer
775 views

Image Contrast Enhancement based Sub-histogram Equalization Technique without Over-equalization Noise

I'm a computer science student and I have an assignment requiring me to implement the algorithm proposed by this paper but I'm hitting a roadblock trying to understand the implementation of one of the ...
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2answers
3k views

Making an EQ from cascading filters

I hope this isn't a dublicate . I checked but maybe didn't see everything. Here goes : I've been scratching my head over some EQ related questions. I read a lot of papers but my limited math and ...
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1answer
8k views

What does the one-tap equalizer used with OFDM accomplish?

I've read that OFDM normally uses a one-tap equalizer. It seems that a one-tap equalizer could only scale and delay a signal. Why is this useful? I thought multipath was handled through the cyclic-...
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1answer
1k views

General questions on the CMA equalizer

So I recently implemented a CMA equalizer in MATLAB that uses method of steepest descent to converge to the minimal cost. (Im on an equalizer implementation binge). My questions are the following: 1)...
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0answers
880 views

Local histogram equalization

I want to learn computer vision and so I downloaded image processing slides from my university archive. I'm on histogram equalization. Learning about local histogram equalization points me out to this ...
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1answer
3k views

What methods can be used to remove ringing artifacts in the output of a digital filter?

I'm using digital filters to apply spectral mangling-type special effects to audio. When using a digital filter (vsts/standalone DSP programs/outboard digital filter, etc.), especially when using ...
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1answer
97 views

How best to digitize a noisy phone recording for filtering?

How do I digitize an analog telephone recording and filter it with a Chebyshev filter?
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1answer
1k views

How exactly to implement the fractional part of a 'fractional equalizer'?

I have written my own LSE equalizer (that works on the bit level), and literature I have read says that 'fractional' based ones are much better. So how exactly does one get 'fractional' bits? Is it as ...

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