Questions tagged [equalizer]

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Requirements on Signal Spectrum for Fractionally Spaced Equalization

I'm constructing an ultrasonic communication system and I am struggling with the correct parameters for my receiver. In baseband, my channel input signal $x(t)$ has infinite bandwidth, since I use a ...
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Square Root MMSE

Could anyone please explain how to perform the derivation of the square-root MMSE equation using an extended channel matrix H (as it is said in the "A LOW COMPLEXITY SQUARE ROOT MMSE MIMO DECODER&...
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How to choose the training sequence for a zero-forcing equalizer?

I am trying to understand how to design N-tap zero forcing equalizer. For the case of 3 taps, I need a training sequence $z[k]$ which I believe can only take the shape of a pulse [0, 1, 0] to ensure ...
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How does zero forcing equalizer work for consecutive pulses?

If in a digital communication system consecutive pulses are sent over a channel, to avoid ISI, a raised cosine filter is used for pulse shaping. If I understand correctly, then this graph taken from ...
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Why does adding a high-pass or low-pass EQ increase volume?

The following three screenshots show the max volume levels (indicated above the VU meter) of Cuckoo by Tipper if played with: No EQ: -0.5db Headroom High Pass EQ: +2.5dB over Low Pass EQ: +0.4dB ...
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Understanding MMSE equalizer equation

I have read many online materials and journal paper where the equation for MMSE equalizer is given as: $G_{MMSE}$ = $H^H(HH^H+\nu^2I )$ where $H$ is the channel, $H^H$ is its hermitian. $\nu^2$ is ...
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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 ...
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1 vote
1 answer
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where we use estimation and detection in communication system?

I read from the book that we use estimation when we are dealing with analog signal or continuous random variable and the term detection when the transmitted signal is a discrete value even if a ...
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1 answer
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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 ...
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Coefficients of a Zero Forcing linear equalizer for infinite length input

Given a discrete-time white noise model: $$y_k = \sum_{i=0}^{\infty} \alpha^{-i}a_{k-i} + \eta_k$$ where $E(|a_k|^2)=2$, $|\alpha|>1$, $\eta_k$ are uncorrelated zero mean random variables with $E(|\...
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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 ...
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1 answer
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How to choose a fixed adaptation step for decision feedback equalizer

How do I choose $\mu$ - a value of a step size for adaptation in a decision feedback equalizer (DFE) with adaptive reference control (ARC)? For a regular adaptive FIR filter an adaptation step depends ...
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Study materials for Decision feedback equalizer

Looking for books, course notes/slides, or some tutorials on decision feedback equalizers with in-depth details. I appreciate your help.
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How do software equalizers work?

Recently, I have been studying IIR and FIR filters, and trying to create a parametric equalizer using a microcontroller. More specifically, I use the ADC on it to sample the audio at about 44 kHz, and ...
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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 ...
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2 answers
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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 ...
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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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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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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 ...
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1 vote
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What are decision feedback equalizer advantages over linear eq?

I am studying linear and DFE equalization theory. So, the books and the Internet are saying, that linear equalizer uses to inverse z-domain channel function. That means that fir in z-domain with $H(z)$...
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1 answer
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How to use matlab toolbox for 2qam dfe equalizer?

I made Channel equalization with matlab, You can find the code below. ...
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1 vote
2 answers
290 views

Whitening Matched Filters for Equalizer

I was looking at the answer Whitened Matched Filter. It mentions that in case of ISI channel, we can use $g^∗(−t)$ as matched filter. For ISI channel, $r(t)=c(t)∗s(t)+n(t)$ where $r(t)$ is the ...
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2 votes
1 answer
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Approximate IIR filter with FIR filter with energy restrictions

Hi I was presented with this problem I would like some guidance to solve: I am given the following DT channel model: $$C(z) = 1-0.3z^{-1}$$ I am first asked to design an IIR linear zero forcing ...
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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 ...
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Frequency-specific Delay?

So an equalizer manipulates the gain of certain frequencies by use of a variety of filters, as we all know. But is there a way to manipulate delay in a frequency-specific manner? A parametric ...
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1 vote
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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 ...
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how to understand the MIMO zero forcing as a bank of decorrelators?

I am studying the zero forcing as a simple linear receiver for MIMO detection. according to following notes: http://www.ee.ic.ac.uk/bruno.clerckx/All.pdf. The zero forcing can be understood as the ...
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2 votes
1 answer
316 views

Zero Forcing Equalizer in ISI channel

I'm studying on designing 9-tap zero forcing equalizer to remove ISI in the channel. I assumed that the channel response is $h[n] = [0.41, 0.815, 0.41]$ and I tried to calculate bit error rate. When I ...
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3 votes
3 answers
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Programming a parametric equalizer - preventing clipping

I've been developing a music player for Android for many years, and I've recently started working on the implementation of a parametric equalizer. I'm having trouble preventing a gain at one band ...
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2 answers
245 views

Does zero-forcing equalizer need known channel impulse response?

I'm studying some of the basic equalizing structres and I understand how Zero-forcing works, but it seems to me that a known channel impulse response is needed. Am I right? If so, what's the point? I ...
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Parallel equalizer, working for boosts but not cuts

I am trying to replicate the behaviour of a parallel equalizer. The approach is to use a parallel sum of bandpass filters like so: $Response = 1 + bandpass1 * (gain1 - 1) + bandpass2 * (gain2 - 1) + ...
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2 votes
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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 ...
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2 answers
117 views

Linear Equalizers Weights

For linear equalizers, the weights of the equalizer are set to achieve minimum error between the equalized signal and the original input signal. First, a training sequence is sent as input, and the ...
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1 answer
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Deciding an EQ's Center Frequencies

I am currently making a relatively simple EQ of a music app, for which we decide to have 5 bands. Other than that, we want to have a bass boost knob, which, as I view it, is just another Peak EQ ...
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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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FIR Audio Equalizer Crackling Noise

I've implemented a few FIR filters into a song equalizer, but there seems to be a crackling that I'm unsure how to fix. Heres a video for reference: https://www.youtube.com/watch?v=IlzWRYpv0rk. Noise ...
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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 ...
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-1 votes
1 answer
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How to get the MLSEEqualizer work with IFFT and FFT blocks in the communication system?

Matlab MLSEE equalizer works fine with the QPSK modulated signal when the signal is propagated over the multipath channel. However, if there are IFFT and FFT blocks used at TX and RX sides, ...
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Equalizers with low data rate systems

In case of using equalizers with ZigBee systems, what type of fading does the channel show, flat or frequency selective, fast or slow? Is the inter-symbol interference (ISI) problem encountered in ...
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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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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 ...
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2 answers
176 views

Equalize Speaker using impulse response

So I have this school project where my aim is to improve a loudspeaker in general, my idea is to mesure the impulse response of the room using a mic, then use this mesure to conceive a loudspeaker ...
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Equalizer design for spectral gain flatness

I'm trying to design an equalizer for spectral flatness over a 100MHz signal for an LTE channel emulator. A channel emulator simply multiples channel coefficients with an external signal from a signal ...
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Best equalizer for a perfect CSI

Assuming a MIMO system and a perfect CSI (the channel matrix is known), what can be the best equalizer? ZF or others?
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Equalizer coefficients and channel coefficients

Blind channel equalization methods equalize the channel without using the source data and without knowing the impulse response of the channel. Consider the channel to be a single input single output ...
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Received Signal Error vs. BER

It is my understanding that the least squares algorithm (e.g., in equalization) minimizes the received signal error. However, minimizing the received signal error does not necessarily equate to ...
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1 vote
1 answer
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Convolution between two unequal length vectors

Considering an example, where the model is \begin{align} x[n] = \mathbf{h}^\mathsf{T}\mathbf{u}[n] + w[n]. \label{Eq1} \end{align} $\mathbf{h} = [h_0,h_1,\ldots,h_{M-1}]^\mathsf{T}$ of length $M$ ...
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Digital Filter Design Accuracy [duplicate]

Having only dealt with digital filter scarcely, the question dawned to me when I used the firls function in matlab to design an equalizer with a certain gain response. In general, can we prescribe ...
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LMS and delta impulse response- Equalization concepts

I have been reading about equalization and channel estimation in order to apply to my application of estimating trajectory path for a two-wheeled robot. The application is quite similar to ...
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Fequency Domain Oversampling - decimating when going back to time domain

I'm currently trying to simulate Frequency Domain Equalization, and the effect that over sampling in the frequency domain has on the affect of the equalization. If I understand things correctly this ...
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