Questions tagged [lms]

Least Mean Square adaptive filter.

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LMS filter always diverges on Cauchy data? [closed]

Suppose my data vectors $x$ consist of IID Cauchy values. Does LMS filter diverge for all values of step size $\alpha$? I tried some simulations and it appears so. Wondering if this is well-known or ...
Yaroslav Bulatov's user avatar
3 votes
1 answer
128 views

Filtered-X LMS algorithm and built-in MATLAB implementation

I provide a short scheme for forward explanation: There are two sources: noise signal source and anti-noise signal source (2). Noise signal travels through primary path $h_{N_P}$ to microphone (4). ...
lazba's user avatar
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Proof that the estimation error in the LMS filter is uncorrelated

I need to demonstrate that the estimation error in the LMS adaptive filter is white. The LMS equations are the following: $y(n)={\mathbf{\hat{w}}}(n)^H\mathbf{u}(n)$ $e(n)=d(n)-y(n)$ ${\mathbf{\hat{w}}...
Andrea Tani's user avatar
1 vote
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134 views

How to get an impulse response of a MIMO system?

So I have data vectors from a MIMO system and I wish to see the impulse response Any idea how I can proceed with this?
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1 vote
1 answer
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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
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Input (Auto)Correlation Matrix for LMS Adaptive Algorithm

I read quite a few posts regarding the autocorrelation matrix and although some of them were of the LMS adaptive algorithm application, I didn't find an answer to my question. How do I calculate R; ...
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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
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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
4 votes
1 answer
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Fractionally spaced equalizer using LMS algorithm

I am doing a project about the fractionally spaced equalizers on matlab. The goal is to mitigate ISI on the signal using the LMS algorithm to update the tap weights of the FSE. Below i have uploaded ...
Obsidian's user avatar
0 votes
1 answer
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What is limited this FXLMS performance

This is simulation data flow: ...
mohammadsdtmnd's user avatar
1 vote
1 answer
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Modeling end-blown flute instrument using adaptive filter

I want to find the resonant frequency of specific end-blown flute called Persian ney, Using LMS in arrangement of system identification. Two signal is needed for algorithm: system excitation (...
mohammadsdtmnd's user avatar
4 votes
0 answers
126 views

For which values of step size is LMS filter stable?

For which values of step size $\alpha$ is LMS filter stable? I Wikipedia information on this question is incorrect. For data sampled from zero-centered Gaussian in $d$-dimensions with identity ...
Yaroslav Bulatov's user avatar
2 votes
1 answer
138 views

LMS Adaptive Filter for system identification

i am currently attempting system identification using the LMS algorithm. The input and the output data are available and are very noisy and consists of multiple frequencies. The input and the output ...
Ayushya Pare's user avatar
1 vote
0 answers
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Grey Box system identification using LMS algorithm

The transfer function and the input output data of the system are known. The transfer function is given by $$G(s) = \frac{K}{(Js+b)(Ls+R)+K^2}$$ How are the parameters of the transfer function ...
Ayushya Pare's user avatar
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60 views

OFDM with frequency domain LMS-based channel estimation

For OFDM, we usually perform least-square (LS) channel estimation using a set of training symbols. We usually do LS channel estimation per subcarrier in the frequency domain as follows: $$ \hat H_{LS}[...
Amro Goneim's user avatar
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Textbooks which derive largest usable rate for standard LMS filter?

Suppose $x$ is sampled from standard 0-centered Gaussian in d-dimensions, and I apply the following iteration. $$w \leftarrow w-\alpha x \langle w, x \rangle \tag 1$$ What is largest $\alpha$ such ...
Yaroslav Bulatov's user avatar
3 votes
2 answers
180 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
1 vote
1 answer
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LMS adaptive filter - is it Least mean square or least mean squares?

It seems both names are used for the same algorithm: least mean square - mainly literature before 1990, for example: Widrow, Bernard, and Samuel D. Stearns. "Adaptive signal processing prentice-...
matousc's user avatar
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When is Normalized LMS better than LMS?

I see mention that normalized LMS "usually converges faster than LMS", in Diniz "Adaptive Filtering" p.152, can this be made more precise? IE, for which signal distributions does ...
Yaroslav Bulatov's user avatar
4 votes
1 answer
516 views

Using Least Mean Square (LMS) Filter for Beamforming on Linear Array in Julia

I have been trying to implement a simple LMS adaptive beamforming code. Since I don't have a MATALB license, I decided to use Julia since they are quite similar. In order to get a basic code working I ...
Kristoffer Lindvall's user avatar
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148 views

Impulse Response and Frequency Response of a FBLMS filter

Suppose I work with sampling frequency FS and block length of L. I implemented the Frequency-domain Block LMS (FBLMS) algorithm ...
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1 answer
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Why Wiener filter is not optimal?

I am investigating Wiener filter in the frequency domain, given by $$ W(\omega) = \frac{S_{ud}(\omega)}{S_{uu}(\omega)}$$ where $S_{xy}(\omega)$ is the cross-power spectral density (CPSD), see scipy....
Triceratops's user avatar
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NLMS algorithm greatly attenuating signal

Im writing an NLMS MATLAB program to remove powerline noise from ecg signals. I sweep through tap widths and learning rates which get the best SNR values. Some of the combinations produce great SNRs ...
Paul Kumar's user avatar
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53 views

what is the difference between LMS and MPC?

I do understand that MPC is a control method and requires known model in the feedback path. LMS, on the other hand, is more like an adaptive filtering, which estimates the tap coefficients yielding ...
Emmmm's user avatar
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What is causing my ANC LMS update to diverge?

I'm trying to implement a simulation of an ANC system with python, using this model here. My simulation keeps diverging, and I honestly don't know why. I'm using a source for LMS adaptive filter from ...
Vincent Lu's user avatar
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1 answer
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What is the input dimension for LMS update algorithm

I just realized this forum existed, posted my question on the wrong forum. Sorry about the formatting, please don't hesitate to ask if any part of this post is unclear. This is my first post. I'm ...
Vincent Lu's user avatar
5 votes
1 answer
682 views

LMS Convergence and the Step Size ($ \mu $) Parameter

I am running the LMS algorithm based on Haykin's Adaptive filter theory. I aim to plot the cost function $\mathbf{J}$ and calculate $\mathbf{J}_{\tt min}$ and the simulation excess mean square error $\...
k_gelloch's user avatar
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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 ...
Aren dg's user avatar
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1 answer
442 views

IIR Adaptive Filter in MATLAB

Suppose I have a IIR filter represented by $$G_0\left(z\right)=\frac{1}{1-0.2z^{-1}-0.1z^{-2}}$$ I would like to use the LMS algorithm to model an FIR filter $G\left(z\right)$ of order $N = 15$ such ...
JordenSH's user avatar
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1 answer
168 views

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 ...
megasplash's user avatar
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1 answer
197 views

How to evaluate fixed-point implementation of LMS filter is correct?

I am having an LMS block with 6 filter coefficients. The value of filter coefficients are 0.0001 0.00045 0.2535 0.546536 0.0000243 0.3423 I have tried to ...
Deepa's user avatar
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Block NLMS vs Affine Projection LMS

I am studying Block Normalized LMS, and when I compare this with Affine Projection LMS (if updated every M samples) I think that they are the same. I would really appreciate if anyone can point out if ...
Copernicus's user avatar
0 votes
2 answers
1k views

How to calculate EVM in %age of an Equalized Constellation in 16QAM?

I have an equalized constellation for 16 QAM. The constellation is equalized by LMS algorithm. I want to calculate the EVM for the equalized constellation. How can I calculate this so that the EVM ...
Umar Farooq's user avatar
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38 views

Capture the ambient sound

I sit in a cafe and start recording my voice, reading a poem. Then I sit at my room, at complete isolation, and I read the same exact poem once again and record it. Now, Considering I have these two ...
William The conqueror's user avatar
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1 answer
278 views

Why is the error between the desired signal and estimated signal in the case of LMS filter remaining constant even after n number of iterations

I am giving white noise as input to an adaptive filter which is initialized to zero (value of filter coefficients of adaptive filter is 0). I am getting a desired response $d(n)$ by passing white ...
Deepa's user avatar
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8 votes
1 answer
346 views

Beamformer implementation methods

I'm currently reading articles about the different type of beamformers. This spatial filtering is gonna be used for acoustic purposes, to focus the beam on the person we need to hear talking in a ...
zou's user avatar
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4 votes
1 answer
340 views

Estimate Instantaneous Frequency Using LMS Algorithm

I hope someone can help me with the following problem: I want to estimate the frequency of a sound file that is composed of a sinusoidal with varying frequency and additive white noise: $$ x \...
Phobos's user avatar
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Length of the FIR filter in LMS algorithm

I'm working on an interference cancellation problem where interfering signals are two linear FM chirps of different slopes and the data signal is a spread spectrum signal. I wanted to know how does ...
Amu's user avatar
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1 vote
1 answer
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Unknown symbol/expression in text about adaptive filters (cst)

I am currently reading a chapter about adaptive filters from the Springer Handbook of Speech Processing. In a formulation of the variable stepsize normalized least mean squares (VSS-NLMS)-algorithm, ...
Jonas Schwarz's user avatar
2 votes
0 answers
451 views

Feedback Filtered-x LMS algorithm: question about theory

I was reading some of papers about the Active Noise Cancellation; in particular about the Filtered-x LMS algorithm, also known as FxLMS. It seems that classic FxLMS (also called Feedforward FxLMS) ...
rainbow's user avatar
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LMS adaptive filter noise suppression- question about my implementation

I am writing LMS filter to suppress noise in wav file (I know there are many modules to do this but I need to write LMS manually now as I will translate it into C later). According to this answer[1], ...
Mahiro's user avatar
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1 vote
0 answers
250 views

Active Noise cancellation for non periodic signals

I observed that the coded algorithm for active noise cancellation is not able to cancel some of the signals like a human voice. Is there any solution for this? Can we really cancel non-periodic ...
Ramakrishna's user avatar
1 vote
1 answer
297 views

Can Temperature Data be Predicted Using Adaptive Filter (Such As LMS) Algorithm?

I am working on a project which requires me to implement adaptive filter as a predictor. I have just started on adaptive filter and I intend to use least mean square algorithm for weight adjustment. ...
Zia's user avatar
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2 votes
2 answers
552 views

Implementation of Block LMS

In the implementation of block LMS, i need one clarification. In the 3rd step as shown in the figure attached, the summation over a product of input, $\mathbf{u}$ and error, $e$, associated with each ...
Ramakrishna's user avatar
2 votes
1 answer
185 views

Seperation of wideband and narrowband - Adaptive Filter

I have the following diagram for the adaptive seperation of a narrowband and wideband signal using LMS algorithim, The way it was explained to us was that "The narrowband signal is correlatied over ...
AlfroJang80's user avatar
1 vote
0 answers
39 views

NLMS Echo Cancellation: How do we estimate when the time-step at which the Far-End Echo will be generated?

I'm new to this domain. From my understanding, we do the following in our algo: ...
spade123's user avatar
1 vote
1 answer
683 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 ...
SKM's user avatar
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0 votes
1 answer
1k views

Recursive Least Square Adaptive Linear Equalizer

For the adaptive filter to work properly, a desired signal d(n) needs to be provided. The output from the equalizer y(n) is subtracted from d(n) to produce an error signal, which is used to adjust the ...
user24907's user avatar
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1 vote
1 answer
81 views

Fair performance comparison betweem LMS & NLMS

How can I choose the step size $\mu$, when I'm comparing different algorithms such as LMS, NLMS and transform domain adaptive filters, regarding their convergence speed, to get a fair comparison ...
Don's user avatar
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1 vote
2 answers
5k views

what is an alpha filter?

Currently, I'm working on adaptive beamforming using LMS approach, so they change the value of the step factor adaptively in which one of the steps is to pass the weight vector through an alpha filter....
Yashvanth Lakshminarasimhan's user avatar