Questions tagged [lms]

Least Mean Square adaptive filter.

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1 answer
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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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5 votes
2 answers
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Explain the Adaptive Part of Adaptive Algorithms - Kalman Filter and Least Mean Square / Constant Modulus

General questions: Is the Kalman filter (they have used Unscented Kalman Filter) adaptive or not? Is the Unscented Kalman Filter used in the paper an adaptive algorithm? Adaptive algorithms such as ...
Ria George'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
5 votes
1 answer
317 views

Model Validation After Estimation for System Identification Task (Assistance with MATLAB Code)

QUESTION: I want to determine how well the estimated model fits to the future new data. How do I validate the estimated model...what is the procedure? After system identification, how to do model ...
Ria George's user avatar
4 votes
1 answer
635 views

Variable Step Size LMS vs Leaky LMS Adaptive Filter Algorithm

What is the advantage of Variable step size LMS over Leaky-LMS adaptive filter algorithm? Which one has a better performance?
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4 votes
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
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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4 votes
2 answers
758 views

Why does block LMS have the same performance as LMS?

The block LMS and conventional LMS have the same convergence rate and the same misadjustment. I am having trouble wrapping my head around this. The block LMS uses a more accurate estimate of the ...
Dres's user avatar
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4 votes
1 answer
152 views

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
4 votes
1 answer
514 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
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
4 votes
1 answer
3k views

Maximum Likelihood Estimator (MLE), MMSE and LS - Are All of Them Regressor, Estimator and Predictor?

Can all three criteria ML, MMSE, and LS be called regressor, estimator, and predictor ? If not, an intuitive explanation of why they can't be, would be good.
mohammadsdtmnd's user avatar
3 votes
1 answer
403 views

Doubts on LMS derivation

I have been trying to follow the Least Mean Square(LMS) algorithm derivation given by Wikipedia here and have the following questions. Here I expected $y(n)$ is to be computed by convolving $x(n)$ ...
Sajil C K's user avatar
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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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3 votes
1 answer
162 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
3 votes
1 answer
317 views

Recursive DCT implementation

I am trying to understand the recursive implementation of the DCT on the input signal (used for LMS filtering) according to the pictures below. The pictures and formulas are taken from the paper: "...
Don's user avatar
  • 165
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
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
2 votes
1 answer
252 views

Why is my NLMS filter off by +/- 2?

I haven't done any signal processing in a while, but I'm completely stymied by the instability and bias in my implementation of a normalized least mean squares filter. I checked the usual things: Am ...
bright-star'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
2 votes
0 answers
74 views

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
2 votes
0 answers
450 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
  • 197
2 votes
0 answers
106 views

Normalized LMS with a posteriori Error and Woodburry's Matrix Inversion

I was going through this paper and the author mentioned that we can prove the following using the Matrix Inversion Lemma (AKA Woodburry's Matrix Inversion Identity): Using matrix inversion lemma we ...
Copernicus's user avatar
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
1 vote
1 answer
1k views

Unable to understand the derivation of the update equation for LMS

I am trying to follow the derivation of the Least Mean Square https://en.wikipedia.org/wiki/Least_mean_squares_filter#Proof but I cannot get the update rule. I am stuck in the following steps and ...
Srishti M's user avatar
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1 vote
1 answer
68 views

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
  • 667
1 vote
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 vote
1 answer
37 views

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
1 vote
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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1 vote
1 answer
682 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
  • 611
1 vote
1 answer
91 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
1 answer
49 views

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
1 vote
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
1 vote
1 answer
42 views

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
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
  • 13
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
  • 165
1 vote
1 answer
479 views

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 ...
Ria George's user avatar
1 vote
0 answers
38 views

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
0 answers
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?
user avatar
1 vote
0 answers
68 views

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; ...
EricH's user avatar
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1 vote
1 answer
111 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
27 views

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
1 vote
0 answers
113 views

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
1 vote
1 answer
201 views

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
1 vote
0 answers
152 views

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
  • 11
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
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
0 answers
323 views

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 ...
Naveen's user avatar
  • 418
0 votes
3 answers
2k views

LMS Algorithm: How to Define the Desired Signal

I am working on LMS algorithm,i am not getting exactly how we get desired response of the filter that is compared with the estimated output
sumaira's user avatar