Questions tagged [lms]

Least Mean Square adaptive filter.

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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 ...
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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-...
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Excessive low frequency component of electroaccoustic system impulse response

I'm using GNU Octave to achive speaker to my laptop microphone path impulse response. For this I use NLMS system identification algorithm. I've analyzed impulse response of system with fft to being ...
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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 ...
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LMS adaptive filtering of signal with specified cross correlation

My signals $x$ and $d$ (desired) has cross-correlation of: I'm testing my code to do system identification using these two signal (signals are white noise generated by GNU octave ...
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CMCIS library LMS does not converge

I have written this code with CMSIS DSP lms filter, but it does not converge, Ive checked input and desiered signal feed to filter but I think both are ok, both are in range of int32_t converted to ...
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Modeling system with return by LMS adaption

I want to model the accoustic system which have some return from its input. I think return from this system will not damage LTI assignment. To identify system I'm using LMS adoptive filter, by ...
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5 votes
1 answer
132 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 ...
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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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Automatic Gain Control (AGC) by using Least Mean Square (LMS) Method

I am try to do Automatic Gain Controller by using Normalized LMS. Can somebody help me? I could not find how to start it. I am try to do it on MATLAB.
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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....
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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 ...
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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 ...
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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 ...
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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 ...
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6 votes
1 answer
315 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 $\...
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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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281 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 ...
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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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1 vote
1 answer
135 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 ...
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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 ...
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2 answers
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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 ...
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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 ...
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1 answer
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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 ...
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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 ...
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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 \...
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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 ...
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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, ...
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318 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) ...
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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], ...
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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 ...
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1 answer
230 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. ...
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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 ...
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2 votes
1 answer
132 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 ...
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1 vote
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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: ...
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1 vote
1 answer
607 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 ...
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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 ...
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1 vote
1 answer
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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 ...
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2 answers
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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....
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161 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 ...
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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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1 answer
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Block LMS with overlapping blocks

In the Block LMS algorithm, the input is partitioned into nonoverlapping blocks of size $L$ and the filter coefficients are updated once every $L$ samples. Would convergence improve if we used more ...
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4 votes
2 answers
624 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 ...
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3 votes
1 answer
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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 $x(n)$ ...
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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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-1 votes
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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?
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Error plot between known and estimated data

The channel is an FIR model with input $u$. The input takes in values which are symbols from some constellation. Using an equalizer such as the Least Mean Squares (LMS), I estimate the input to the ...
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2 votes
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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 ...
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3 votes
1 answer
231 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: "...
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5 votes
1 answer
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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 ...
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