Questions tagged [lms]

Least Mean Square adaptive filter.

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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
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
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
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2 votes
0 answers
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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
0 answers
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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
0 answers
133 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
0 answers
67 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
106 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
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
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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
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
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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
0 votes
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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 ...
Triceratops's user avatar
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0 answers
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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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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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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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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192 views

Generalized Sidelobe Cancelling performance

I'm tinkering with different adaptive beam-forming algorithms for a research project in which I want to use a Uniform Rectangular microphones Array (URA) to isolate speech in a room. I am determining ...
Florent's user avatar
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158 views

Gradient descent applying chain rule in state space setup

Trying to perform system identification in the following state-space model $$ \begin{bmatrix} x_{1}(n)\\ x_{2}(n) \\ x_{3}(n)\end{bmatrix}=\begin{bmatrix} a_{11} && a_{12} && a_{13} \\ ...
niaren's user avatar
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0 votes
1 answer
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Two type of calculating R in steepest-descent modeling algorithm

I have wrote this algorithm for steepest descent: ...
mohammadsdtmnd's user avatar
-1 votes
1 answer
3k views

What do the filter coefficients in digital filter represent?

Could you help me? How can I understand the function of the filter coefficients practically? In the simple case, it is the impulse response of the LTI system. but how do they work?
reem's user avatar
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