Questions tagged [equalization]
The equalization tag has no usage guidance.
122
questions
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1answer
33 views
ZP-OFDM vs. CP-OFDM channel equalization
Now, I am working on OFDM equalization, according to what I understood, Adding CP into the OFDM block change the convolution from linear to circular. That circular convolution enables using point-wise ...
0
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0answers
18 views
Equalization of ultrasonic transducer [duplicate]
I am working with ultrasonic transducers with frequencies 100 kHz, one for transmission one for reception. The transmitted signals are chirps. I would like to measure the time of flight between ...
0
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2answers
81 views
Distortion of OFDM signal when using RRC filter
I am trying to transmit OFDM signal in pass-band based on RRC filter, but what I noticed that the signal before the RRC filter is completely different compared with signal after the RRC filter (It ...
0
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1answer
44 views
Should we upsample the channel when upsample the signal
I have an OFDM system with Number of sub-carriers $N= 1024$, modulated data using $QAM$ modulation is transmitted via those subcarriers as follows:
...
0
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1answer
38 views
Convolution that outputs a unit impulse
Im thinking whether any convolutional operation can output a unit impulse, an example to further explain:
where a convolution between system $h[n]$ and unknown system $g[n]$ would output $\delta[n]$.
...
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0answers
23 views
Time Reversal OFDM
I am trying to understand the Time Reversal OFDM where ,According to my opinion, the channel is reversed in time domain at receiver side and then equalized.
what I found online is something similar ...
0
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1answer
41 views
What's the computational complexity of MMSE equalizer in OFDM system
As I know that in case of one tap OFDM equalizer, (ZF equalizer), we should have $N$ division complexity since we divide every subcarriers by its correspondent channel tap in frequency domain.
But I ...
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0answers
11 views
chromatic and polarization mode dispersion compensation in electrical dmain
I am currently working on adaptive compensation of chromatic and polarization dispersions in the electric domain using LMS (least squares method) and CMA (constant module algorithm) algorithms.
I am ...
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0answers
39 views
How to implement Minimum mean-squared error (MMSE) equalization?
I have the channel estimation and noise power estimation and I need a matlab implementation of time domain siso channel Equalization.
Theory:
Consider the FIR filter of length $N+1:$
$$
\hat{s}_{k}...
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0answers
38 views
On the channel estimation based on vector
I have a matrix $X$ of size .i.e $(8,8)$ with $M$ columns and $N$ rows. Suppose I took it's $iFFT$ column wise resulting matrix $x$ of size $(8,8)$ too,
$x = F^HX_{(:,m)}, $ ...... (1),
where ...
1
vote
1answer
34 views
Is DFE equalizer always blind or can we use reference signal?
I have made a blind DFE Equalization, I mean decision directed .
But I am not sure how to make an implementation based on reference signal known by receiver and emitter. In the back forward filter ...
1
vote
1answer
38 views
How to use matlab toolbox for 2qam dfe equalizer?
I made Channel equalization with matlab,
You can find the code below.
...
1
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1answer
86 views
The use of LS estimation with Vector OFDM
I work in Vector OFDM, but I had an issue in channel estimation in that scheme. For example, I try to use LS channel estimation but I can't get the performance back. However, in conventional OFDM, I ...
0
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1answer
76 views
Channel estimation and interpolation by vector in OFDM
I have V-OFDM system (Vector OFDM) where every symbol is organized as in below figure:
The black cirles are pilots and white circles are data. First, iFFT operation it taken per column, and then ...
0
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2answers
46 views
OFDM time vs. frequency domain channel estimation/equalization
In OFDM, the majority of Equalizers are used in frequency domain. I mean the signal is transmitted in time domain (after performing iFFT), then to estimate the channel we should perform FFt to use ...
0
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1answer
41 views
Effect of Adding the cyclic prefix on the toeplitz matrix in OFDM
Assuming we have $N$ symbols to transmit encoded in block $k$,
Performing $N$āiFFT at the transmitter, we now have
The resulted signal $x(k)$ has length of $N$. inserting a cyclic prefix $CP$ ...
0
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0answers
26 views
How to compute the DFE based MMSE equalizer FF and FB coefficients in a non adaptative way?
I seek your assistance,
I am reading the Proakis 5th edition and I came across a paragraph explaining the tuning of DFE filters, i.e, how to compute the FF(FeedForward) and FB (Feedback Filter) ...
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27 views
Code implementation of Channel estimation based DFE Equalizer in matlab (or octave) without the the signal processing tool box
I want to implement a DFE in matlab without the signal processing toolbox:
I have two filters ( FeedForward and FeedBack) with taps length equal to 15.
I know the update equation of the LMS ...
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0answers
6 views
How to choose the algorithm for DFE filter adapatation, if the criterion is MMSE?
I hesitate between LMS and RLS ,
and for the feedforward filter and feedback filter, what must be the length of the filters as a function of the channel delay spread.
Any help will be really ...
0
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1answer
41 views
MMSE- Channel estimated based - DFE Equalization
For HF ionospheric channels ( frequency range 3 up to 30 MHz), I Want to make channel equalization in time domain, using MMSE criterion. I have to do it using the channel estimation.
I have some ...
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0answers
58 views
Is MMSE equalizer necessary?
For observation $y$, channel coefficient $h$ and gaussian noise $w \sim \mathcal{CN}(0,\sigma^2)$,
$$y = hx + w \tag{1}$$
Note that for OFDM system, (1) is assumed channel input-ouput equation on ...
0
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1answer
36 views
Adaptive equalization vs inverse of transfer function
I have the following equalization problem as shown in the figure below:
Now I can compute the coefficients for my adaptive FIR filter c (dim(c) = N) the following:
$\mathbf{c_{opt}} = (\mathbf{H}^T\...
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0answers
79 views
should implementing the MMSE equalizer in time domain and frequency domain give same results?
Assume we have a received signal $r$ explained as below:
$r = h * x + n$
where $h, x ,*, n$ denote to the multi-path channel, transmitted signal, convolution operation and AWGN, respectively.
...
3
votes
0answers
39 views
Block CMA algorithm
The Constant Modulus Algorithm is a common equalization method which adapts at every sample in an attempt to give a filter which produces a fixed power output. Divergence/convergence of the CMA ...
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0answers
13 views
Simulation of channel equalization in data transmission systems
As a newbie in the field, I need your help in breaking this down step by step.
2
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1answer
99 views
Output of Zero-forcing equalizer doesn't match theoretical calculations
Let's say I have a sequence $x[n]$ (signal) and perform convolution with another sequence $h[n]$ (channel), so:
$$
y[n] = h[n]*x[n] = \sum_{k}{h[k]x[n-k]} \leftrightarrow Y(z) = H(z)X(z)
$$
I'm ...
0
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2answers
76 views
Types of equalizers
I can't get my mind around the different types of equalizers and the difference between some of them. I've been looking at different books unsuccessfully.
So far, I have Wikipedia's list and this ...
2
votes
4answers
260 views
What Information Is Lost by Histogram Equalization?
I cannot think of a way to restore an original image after histogram equalization. But this latter seems to "enhance" (= increase contrast of) the image's details. What information is then lost by ...
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1answer
19 views
Question about image equalization
Let $f$ be an $N \times M$-image and suppose that $g$ is its equalization.
Question - Why the equalization does not change the objects, why a car on $f$ does not convert into a bus on $g$?. It is ...
0
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1answer
94 views
On the signal recovery in OFDM after estimation
Given a modulated signal X which is transmitted based on OFDM with N = 256 sub-carriers through channel ...
0
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0answers
57 views
Clip wav by PSD
I have the following two things.
sequence_1: Sound file in the wave format.
PSD_1: Some PSD (Power Spectral Density).
I want that the PSD(sequence_1) < PSD_1 for all indices.
How I think about ...
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0answers
21 views
Converting the equalizer coefficients from VSA at 2 sample/Symbol to 1.5 sample/Symbol
I was looking for some feedback on conversion of equalizer/filter coefficients at different sampler rate.
Problem Statement:
We have built a transmitter system whose output is at 1.5 sample/symbol (...
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0answers
17 views
How to exploit auditory masking to boost intelligibility
I am currently working on a dynamic equalizer to improve a synthesized voice's intelligibility in noisy environments.
The current implementation of my algorithm simply applies a parametric EQ to the ...
1
vote
1answer
71 views
Training Fractionally Spaced Channel Estimator and Equalizer
If you are attempting least squares channel estimation with a fractionally spaced channel estimator, do you want the training sequence to also be fractionally spaced or symbol spaced? It looks like ...
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0answers
79 views
Digital Communications block diagram question
I am new to digital communications and trying to understand the basic underlying concepts of digital comm systems. So far , studying the course , I have some questions which if anyone can answer would ...
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0answers
170 views
The Definition of Q Factor by an Equation and How to Graph
I am currently building an EQ in an music app, and it's relatively simple:
6 bands of fixed center frequency, and a Q knob to control the Q of all bands, because we do not currently have space for ...
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1answer
89 views
Is CMA equalization applicable for OFDM
I have a question regarding the constant modulus algorithm (CMA), as you know it's one of the known algorithms used for blind equalization. The cost function of the CMA is build blindly, it means ...
1
vote
1answer
121 views
Where in the signal chain is Channel Equalization applied?
I am reading about channel equalization and I am somewhat confused on where in the signal chain channel equalization is normally applied and if it's before or after a correlator detector or matched ...
3
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1answer
349 views
What is the difference between an equalizer and a channel estimator?
I was wondering what is the difference between channel estimator and channel equalizer?
Thanks!
0
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1answer
46 views
Need information about following channel model
The following research paper is for blind channel equalization and the author has modeled the channel as 7 tap weights
https://ieeexplore.ieee.org/document/1096877
On page 3 it has shown the ...
0
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1answer
42 views
Equalizing a temporal sound signal with a convolution
This question is more or less the following of a previous question.
The aim is to equalize some sounds signals. By equalizing, I mean increasing or decreasing some frequency ranges, a bit like an ...
0
votes
1answer
156 views
Inter-Symbol Interference (ISI) channels
Is there any open and free data-set for digital ISI channels? I want to have a variety of ISI channels' taps, such as $h[k]$ here. Especially looking for BPSK channels.
0
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1answer
69 views
Is the Channel shortening similar to Time domain Equalizer (TEQ)
I used to read about Time domain equalizer (TEQ) in many lectures, i.e here , But in many other papers, that's called Channel shortening i.e here .
However, in the a two above links, the cost ...
0
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1answer
48 views
how to set Equalizer's coefficient using generalized eigenvector.
In that paper https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/1687-1499-2012-72 .. Equation 3,
$J(w) = w^HBw/w^HCw$ ..
$B$ and $C$ are matrices, $w$ the filter coefficients vector ...
1
vote
1answer
405 views
estimate the impulse response after equalization
I want to estimate the impulse response of the channel at the receiver. Assuming
some arbitrary impulse response: h=[1 0.2 -0.4 0.0 0.6]. Once the equalizer is ...
2
votes
1answer
49 views
BER performance of fractional equalizers for colored noise
I am trying to compare the BER performance of fractional and symbol spaced equalizers for channel equalization in colored noise scenario. I have found from simulation that for positively correlated ...
0
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1answer
73 views
What's the difference between Channel shortening and time-domain equalizer
I'm asking about the difference about channel shortening and time-domain equalization. I have checked on-line and tried to get something clear but I couldn't.
What I found is that channel shortening ...
4
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1answer
215 views
What is the difference between pulse shaping and equalizers when used to cancel Inter-symbol Interference (ISI)?
According to Nyquist, to transmit R symbols/sec without ISI, the minimum bandwidth required is R/2 Hz, and the sinc pulse shape satisfies this condition.
If we use equalizers instead of pulse ...
0
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2answers
470 views
Inter Symbol Interference (ISI) / Equalization in Digital Signal Processing
I am studying the OFDM system and before to start I have decided to study the main concepts of modulation. And I have spent yet a lot of time to understand the concept of an equalization to reduce ISI....
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0answers
283 views
Blind equalization with constant modulus algorithm in GNU Radio
I'm currently simulating the effect of multitap channel on BPSK as well as its remedy i.e. equalization.
The modem is expected to work with satellite TT&C transponder.
The communication channel ...
