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1
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0answers
23 views

Fractional spaced equalizer + timing (clock) recovery

I am trying to figure out how timing recovery is used after equalization (or, being more correct, when the equalizer is in the timing recovery loop), having a T/2 fractional spaced equalizer and using ...
0
votes
0answers
29 views

Adaptive LMS(Least Mean Square) Equalization in OFDM

I have a problem with the adaptive LMS frequency domain equalization in OFDM. When I assume that the receiver knows the channel perfectly and apply zero forcing equalizer, there is no problem. Also ...
0
votes
2answers
41 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 ...
0
votes
0answers
27 views

How to calibrate two microphones to same frequency range

I am recording stereo with two same microphones but they are physically insulated from eachother and have some additions on sound input side. Not to complicate story, I have a human head simulation ...
0
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1answer
24 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 ...
0
votes
0answers
24 views

Channel length, Cyclic prefix length and number of channel taps relationship

In the design of a communication system, specifically multi carrier OFDM system and DMT/OFDM, I would like to understand the relationship, if any, between the following parameters: Channel length ...
0
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0answers
20 views

Equalizers for controlled ISI and ICI

I am new to the physical layer and may not have all the necessary background. I have the following question on the design of Equalizers. Equalizers to combat the effect of ISI and ICI due to ...
0
votes
0answers
20 views

Matlab :Where am I going wrong in applying cumulant 4 algorithm

I need to apply Higher order cumulant -the 4th cumulant algorithm as an equalizer for blind equalization. The code returns only 5 samples for each signal-to-noise ratio and as a result, when ...
0
votes
0answers
52 views

Matlab: Help in simulating the symbol error rate for higher order QAM modulation

I am trying to calculate the Bit Error rate (BER) for 16 and 64QAM modulation for channel equalization using Subspace algorithm. The algorithm / code works fine without the BER calculation. ...
1
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0answers
37 views

Matlab: Unable to perform equalization by higher order cumulant

I need to apply Higher order cumulant -the 4th cumulant algorithm as an equalizer for blind equalization. The code returns only 5 samples for each signal-to-noise ratio and as a result, when ...
0
votes
1answer
74 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
votes
2answers
81 views

Why are equalizers moving average model (FIR)

Let the equalizer coefficients obtained, say $w$ and the input to the equalizer is $y$ that is a noise corrupted received signal, $rx$ then the equalized signal, which is the output of the FIR based ...
2
votes
1answer
366 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 ...
2
votes
0answers
148 views

Matlab: Help in understanding and applying Rayleigh effect and equalization

I am trying to simulate a flat fading Rayleigh channel for BPSK modulation. Then I want to apply Minimum Means Square Algorithm for channel equalization, assuming full knowledge of the channel ...
2
votes
1answer
222 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 ...
1
vote
1answer
52 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 ...
0
votes
0answers
29 views

Histogram normalization for normalizing background changes

I recorded a sequence of depth images using Kinect v2. But the background brightness is not constant. But It keeps changing from dark to light and light to dark (i.e) So I was thinking to use ...
0
votes
2answers
165 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 ...
2
votes
1answer
125 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 ...
2
votes
1answer
590 views

MATLAB : Proper estimation of weights and how to calculate MSE for QPSK signal for Constant Modulus Algorithm

I had asked conceptual Question about Constant Modulus Algorithm. I am implementing the simple steps of the algorithm, as I do not have the cma() built in module. ...
0
votes
2answers
173 views

Decibels conversion into amplitude ratio

I want to convert db into amplitude ratio. I did some research but I only found online convertor, and I don't understand what's on Wikipedia very well... Here is a little of backstory : I am a ...
1
vote
1answer
79 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. ...
1
vote
0answers
67 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 ...
0
votes
1answer
557 views

Histogram matching (specification) in Python

I'm trying to implement an algorithm in which I first pad each row of the image with a fixed amount of new pixels in a certain range, apply Gaussian smoothing to the row cumulative histograms in ...
1
vote
4answers
39 views

Performing image equalisation and then Jpeg compression

I'm trying to estimate what would be the result of first performing an histogram equalisation on an image, and then compressing it using JPEG. I know that histogram equalisation increases the ...
0
votes
1answer
166 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 ...
1
vote
0answers
724 views

DFE for QPSK in MATLAB

I need to do a DFE for QPSK simulation in MATLAB. The system consists of a QPSK signal transmitted with power = 1 which is then pulse shaped with a square raised-cosine filter. Add AWGN and a filter ...
2
votes
1answer
74 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 ...
1
vote
1answer
70 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 ...
0
votes
0answers
87 views

non linear equalizer vs linear equalizer

i understand that there are linear equalizers such as MMSE and ZF, however there are also non-linear equalizers such as MLD. i would like to know what is the difference between a non-linear equalizer ...
0
votes
1answer
53 views

maximum likelihood derivation

as you can see on page 314 the derivation of the ln[f etc.] equation is done via the matched filter that i have also provided below. i would like to know how this equation is used to derive the ln[f ...
2
votes
0answers
81 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 ...
-1
votes
2answers
71 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 : ...
0
votes
2answers
446 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 ...
4
votes
4answers
2k 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
votes
1answer
461 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 ...
2
votes
1answer
905 views

Remove a frequency and all its multiple (harmonics)

In a soundfile, I'd like to remove a frequency and all its harmonics. What is the best solution in your opinion ? Do a loop with 20 notch filters, one after another. // f is the fundamental ...
1
vote
3answers
356 views

Berchin's FDLS arbitrary filter design algorithm

i'm trying to use Berchin's FDLS methods (for those that don't know what it is, it's a way to design arbitrary magnitude and phase of an IIR Eq) I tried different things but neither gave me what i ...
0
votes
2answers
1k 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 ...
4
votes
1answer
3k 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 ...
6
votes
2answers
369 views

Conditions for precoding matrix to preserve complex conjugate symmetry on DFT vector

Suppose there is a DFT vector $\mathbf{X}$ with length N, which presents complex conjugate symmetry around its middle point, i.e., $X(1) = X(N-1)^*$, $X(2) = X(N - 2)^*$ and so forth. $X(0)$ and ...
2
votes
3answers
262 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 ...
1
vote
0answers
323 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 ...
6
votes
1answer
1k 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 ...
0
votes
1answer
89 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?
4
votes
1answer
1k 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 ...
9
votes
1answer
614 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: ...
5
votes
1answer
771 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 ...