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How single-tap equalization can be performed in OFDM for perfect channel estimation?

If I have for example IFFT length of 3 with cyclic prefix length of 2 and 3 channel taps, how can I illustrate the frequency domain equalization in OFDM? For example as far as I know, it's elementwise ...
Amitabha Bhattacharjee's user avatar
1 vote
0 answers
46 views

decision feedback equalizer building blocks (from Adaptive Filters: Theory and Applications” a book by Behrouz Farhang-Boroujeny)

Here you can see building blocks of DFE from "Adaptive Filters: Theory and Applications” a book by Behrouz Farhang-Boroujeny in chapter 17. Figure 17.9 shows the overall building blocks of DFE ...
Sadeq Ebrahimi's user avatar
1 vote
0 answers
83 views

Channel equalization in uplink

I have a multiuser uplink signal $$ Y=h_1x_1+h_2x_2$$ where, $h_1$ and $h_2$ are channels for user 1 and user2 respectively. At the receiver how can I equalize the signal $Y$, assuming known $h_1$and $...
Digi1's user avatar
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2 votes
1 answer
150 views

Group delay equalization for second order IIR notch filter

A couple of second order notch filters seem to be appear regularly in the literature (see e.g., Tseng, Chien-Cheng, and Soo-Chang Pei. "Stable IIR notch filter design with optimal pole placement.&...
rhz's user avatar
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1 answer
165 views

Decision Feedback Equalizer initialization

Suppose I want to implement only via software on matlab a DFE. I am studying the decision feedback equalizer but some slightly more practical concepts are not very clear to me from the theory. ...
KaleM's user avatar
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1 vote
1 answer
70 views

LTE PSS Channel Estimation for coarse SSS Equalization

In LTE the Primary Synchronisation Signal (PSS) can be detected by taking a correlation with the known 3 zadoff chu sequences (roots: 25,29,34). Once the peak has been detected the receiver knows ...
Sonny Wandel's user avatar
1 vote
1 answer
83 views

ISI and RRC basic concepts

I've been studying a kind of "introduction" for a few days now to get to talking about equalizers and ISI, and I would like to know if I have understood the things correctly or if I got ...
KaleM's user avatar
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0 answers
29 views

Is OFDM equalization performed every 14 symbols?

The number of symbols and slot in a subframe differs depending on the subcarrier spacing Is equalization processing performed for each slot? Or per subframe?
Ryo Onishi's user avatar
2 votes
2 answers
1k views

do digital equalizers use Fourier transforms?

I’ve been reading up on approaches to pitch shifting, and have found some common approaches use fourier transforms to achieve a change of pitch. I’m curious, is fourier transform technology used in ...
Bruce Simonson's user avatar
1 vote
1 answer
35 views

Separating an audio file into "N" frequencies

I'm working on an audio visualizer using Blender, and I'm wanting to separate input audio files into their respective frequencies to allow my models to react based on the amplitude at different ...
Devin Gardner's user avatar
1 vote
1 answer
99 views

Equalization with FSK

What are the downsides of using an LMS (or least squares) equalizer with FSK signals? What are the tradeoffs on doing equalization pre-demoduation vs post-demodulation? Most literature I can find ...
BigBrownBear00's user avatar
1 vote
0 answers
159 views

Matching two different type of equalizer responses

AutoEq (by Jaakko Pasanen) is an utility for headphone equalization. I'm trying to make a EQ converter for SuperEQ (source code for implementation found in DeadBeef), which can be found on few ...
Juha P's user avatar
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1 answer
84 views

Numerical Stability for Channel Estimation

In this post: Compensating Loudspeaker frequency response in an audio signal I derive the Wiener-Hopf equations for least squares equalization (and channel estimation if we swap Tx and Rx) from the ...
Dan Boschen's user avatar
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3 votes
1 answer
175 views

LMS algorithm: Training and tracking phase

I'm trying to implement a fractionally spaced equalizer to mitigate the effect of ISI on the signal. The block scheme that I'm following is: I'm using the LMS algorithm to update the tap weights. In ...
Obsidian's user avatar
1 vote
1 answer
129 views

Fractionally spaced equalizer - LMS algorithm

I am doing a project in MATLAB about the fractionally spaced equalizer. The method that i have chosen to update the tap weight coefficients is the LMS algorithm. Here is the block scheme that i have ...
Obsidian's user avatar
1 vote
0 answers
53 views

fractionally spaced channel equalizer code [closed]

I want to write a program in matlab for an adaptive fractionally spaced equalizer with lms algorithm.consider each packet with 150 bits that 25 first bits are pilot and used to train weights of the ...
Mahtab's user avatar
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9 votes
4 answers
686 views

Least Squares Solution Using the DFT vs Wiener-Hopf Equations

Least Squares channel estimation (or equalization) can be accomplished using the "Wiener Hopf Equations", or the Discrete Fourier Transform. Both appear to be least squares solutions. How do ...
Dan Boschen's user avatar
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2 answers
194 views

Why do inverted impulse responses sound awful when applied to an audio system?

In this answer, the responder claims that acquiring a measured impulse response and straightforwardly inverting it (e.g. by directly in the spectrum, after zero-padding, or by determining the inverse ...
oliver's user avatar
  • 266
2 votes
2 answers
967 views

Why construct a minimum phase filter from measurements?

Sorry if this is a trivial question, but I am not doing signal processing everyday. I will try to express what I think I have understood as best as possible. Suppose I apply a (linear) sweep signal to ...
oliver's user avatar
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2 answers
217 views

Should we use Maximal ratio combining and an equalizer together?

I have confusion on MRC(Maximal Ratio Combining) method which I would like to clarify. An example is where I have 1 transmit antenna and 4 receive antennas. The concept of MRC is to combine all the ...
SAM's user avatar
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1 vote
1 answer
140 views

main idea of Adaptive histogram equalization (AHE)

I want to understand the main idea behind AHE and the way for applying it manually with my hands. Wikipedia says: In its simplest form, each pixel is transformed based on the histogram of a square ...
hasanghaforian's user avatar
3 votes
1 answer
224 views

Mathematically show the problem of Histogram Equalization

Wikipedia - Adaptive Histogram Equalization says about classic Histogram Equalization: This works well when the distribution of pixel values is similar throughout the image. However, when the image ...
hasanghaforian's user avatar
0 votes
2 answers
232 views

purpose of histogram equalization

What is the main purpose of histogram equalization on image? Is it used to enhance contrast of image or is its goal finding a transformation which gets a more uniformly histogram? Although Wikipedia ...
hasanghaforian's user avatar
0 votes
1 answer
148 views

MATLAB: cannot get CMA code for polarization demultiplexing to work

[ Edit: the CMA code seems to work after all, the problem is likely elsewhere (timing recovery), see added text at the end. ] Yesterday I implemented some CMA code for polarization demultiplexing ...
Jeroen Boschma's user avatar
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0 answers
39 views

Is there any sampling offset when using external reference signal

I perform real experimental tests for optical communications using DCO-OFDM. The transmitted signal is uploaded into an AWG (arbitrary waveform generator), then bias (2.5 V) is added before adopting ...
Sajjad's user avatar
  • 167
3 votes
2 answers
189 views

Can a LMS adaptive filter be adapted for MISO?

How would the LMS equalizer dimensions change for the MISO case? LMS adaptive filters are typically described for equalizing a single input signal, $x(t)$. Can the LMS algorithm be modified in the ...
BigBrownBear00's user avatar
0 votes
0 answers
121 views

Feedforward equalizer MMSE vs ZF: I get ZF performs better than MMSE, why is that?

So I am doing some experiments on comparing MMSE and ZF performance. Here is the description of my problem setup: Consider a pulse response $p_{tilde}$ which is equal to: [7.41283693728174e-06 -6....
Chris's user avatar
  • 1
0 votes
1 answer
304 views

Can I still use match filter (eg.RCC)at rx when there is none at tx? Can it help with ISI?

As the transmitter is restricted to size and power considerations, there is no way to apply a SRRC filter at tx side. Can I just put a RC(raised cosine filter) at the rx side to alleviate ISI?
ztscotty's user avatar
0 votes
1 answer
156 views

Multi-path equalization in SERDES system analysis

In transmitter I send the data 1 sample per bit, then received in Rx passing by ADC then FFE adaptive filter and then a slicer to return the samples in bits and calculate the BER and it works well ...
Aren dg's user avatar
  • 21
5 votes
2 answers
420 views

Group delay compensation for non coincident drivers

Suppose I have a two-way speakers system which can be modeled as a two-way Linkwitz-Riley crossovers network with impulse responses $h_{lp}(n)$ and $h_{hp}(n)$. I would like to equalize the group ...
Spark123's user avatar
0 votes
1 answer
246 views

Pilot-based channel estimation in OFDM systems with fractional delays

Most studies on OFDM-based communication systems consider that multipath channels consists of a limited set of taps in the discrete-time domain. However, this only holds if the tap delay is a multiple ...
Lucas Oliveira's user avatar
1 vote
3 answers
633 views

How are the reflections in a quarter wavelength transformer dealt with in signal processing?

I haven't seen this issue ever explicitly discussed. Briefly, reflections cannot be avoided in a quarter wave transformer due to the characteristic impedance not matching the source or the load. In ...
Lewis Kelsey's user avatar
0 votes
2 answers
197 views

Inverse of filtering and inverse of equalization

Is comb filtering a reversible operation? If applied to a signal, can I restore the original signal from the filtered image? What about the histogram equalization operation? Is it reversible?
Noha's user avatar
  • 349
0 votes
1 answer
789 views

Audio Equalization, Is Parallel or Cascade better

I'm not really an audiophile, so I can't determine the difference. I was playing around with Matlab's Graphic EQ and I noticed that there is a difference in the Magnitude response for the same gain ...
John Smith's user avatar
-1 votes
1 answer
41 views

Equalization in CAR- Automotive Audio

Can someone tell me what is the purpose of CAR Equalization in audio and why before CAR Equalization ,gain adjustments are necessary ? Also why would someone use FIR filters during CAR Equalization ...
Clauvunate's user avatar
1 vote
1 answer
528 views

What phase rotation occurs when you take the derivative of an audio signal?

If you take the derivative of an audio signal, it provides a 6 dB/oct upward sloping filter (increasing high frequencies / cutting low frequencies) all the way across the spectrum. What is the result ...
mike's user avatar
  • 533
0 votes
0 answers
53 views

Upmixing after Equalization [duplicate]

Can anyone tell me why in a stereo mode many channels are derived from the 2 channel input . It looks like upmixing.. My questions are summarized below : If it is Stereo mode why upmix it to many ...
Clauvunate's user avatar
1 vote
2 answers
2k views

Equalizing audio under linux / Raspberry Pi

I have an audio streaming receiver written in Python running on a raspberry pi. This receiver writes the streamed audio out to an alsa device, which in turn passes it to an amplifier which is driving ...
Paul Wieland's user avatar
0 votes
2 answers
364 views

Peaking filter (loudness) cutoff frequency in an equalizer

An equalizer we have consists of Loudness ,Bass ,Mid and Treble .The loudness is nothing but a Peaking filter with cutoff frequency 20Hz .I read this in a book that outlines the EQ design. I was ...
Clauvunate's user avatar
0 votes
1 answer
160 views

Strange results with all pass compensation

I am new to DSP and, as a learning exercise, I am trying to design an all-pass filter in order to compensate the phase of an input impulse response (heqm.mat, which you can download from here). The ...
Spark123's user avatar
1 vote
1 answer
312 views

All-pass phase compensation only in a specific frequency range

I am trying to design an all-pass filter in order to compensate the phase distortion at the output of an equalizer. To do so, I take the phase vector of the output, compute the real and imaginary part ...
skateskate's user avatar
1 vote
1 answer
99 views

Mathematical expression of Multicarrier frequency equalizer

I have a signal $X$ with length of $N$, multiplied with any unitary matrix, i.e the transpose of DCT matrix as: $x = D' X$ where $D'$ is the transpose of the of DCT matrix. Then let's add $CP$ guard ...
New_student's user avatar
0 votes
0 answers
1k views

MATLAB model for equalizer using LMS algorithm adaptive filter and unexpected output curve

The MATLAB code below is for equalizer using lms algorithm adaptive filter and then plotting MSE (Mean Square Error) Vs Iteration numbers ...
Aren dg's user avatar
  • 21
1 vote
1 answer
102 views

The cost function of LS algorithm

I'm trying to understand the derivation of LS algorithm for channel estimation in OFDM. Could anyone explain why do we need complex conj transpose in the below equation?
dcs's user avatar
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0 votes
0 answers
52 views

Compensating for poor illumination across a specific image axis - possible solutions?

A friend of mine is working at an institute for nano-membranes. Currently they are using ImageJ and do a lot of manual (in my opinion inaccurate) work to process some membrane "photos" (...
rbaleksandar's user avatar
2 votes
1 answer
166 views

Channel equalization affect on input signal

I have the following problem. Am trying to understand how the channel block affects the input signal s(n). I know that x(n), the input signal to the filter is basically: \begin{equation} x\left(n\...
JordenSH's user avatar
  • 303
0 votes
0 answers
206 views

Zero padding OFDM equalization

In ZP-OFDM, The convolution is linear. it's different from CP-OFDM which is circular convolution leading to have one tap equalizer in frequency domain. if I have a ZP-OFDM system, and we have a signal ...
Fatima_Ali's user avatar
0 votes
1 answer
491 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 ...
Fatima_Ali's user avatar
0 votes
0 answers
23 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 ...
Deanna77's user avatar
0 votes
2 answers
180 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 ...
Fatima_Ali's user avatar