Questions tagged [adaptive-filters]

An adaptive filter is a filter that self-adjusts its transfer function according to an optimization algorithm driven by an error signal.

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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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What is the relationship between beamforming and Independent Component Analysis (ICA)?

My first inclination when thinking about the Cocktail Party Problem would be to use adaptive beamforming to isolate different signals, but this does not seem to be how the problem is commonly thought ...
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Adaptive Particle Filter: unknown process Equation

In my design and implementation of a SIR particle Filter, I don't have the state process equation of the actual system, which would have given a very good estimation of the real signal. I was ...
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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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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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Filtering out motion noise from ECG

I have some ECG data that have some noise from motion in it. I also have have accelerometer data sampled at the same time. The idea is to use the accelerometer data to filter out motion noise from the ...
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Is a neural network an adaptive filter?

I am confused as to the difference between neural networks and adaptive filters: As far as I understand it, "neural networks" are largely used for solving inverse problems, where an unknown ...
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How Could One Accelerate the Convergence of the Least Mean Squares (LMS) Filter?

How can the convergence of an LMS filter be accelerated? Can we do better than the vanilla algorithm?
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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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real time - active noise control

I am trying to implement an adaptive filter for system identification and active noise control for realtime signal processing on an FPGA using Labview. For system identification, I implemented the ...
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autocorrelation of multiple signals

Problem: I am looking at an adaptive filtering application where the eigenvaluespread of the autocorrelation matrix $R$ is important for the convergence of the algorithm. For a single channel system ...
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Recursive Least Square For Filtering

I just started doing research on Recursive Least Square for filtering noises such as sensors and dc motors noises. The only thing I've seen on the internet was Theoretical information about RLS but ...
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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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3 answers
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How to derive the "well-known" solution to Unconstrained Array Gain?

Can someone point me to a webpage or other resource that shows how to analytically solve the beamformer Unconstrained Array Gain expression in Henry Cox's 1987 IEEE paper "Robust Adaptive ...
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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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Channel equalization affect on input signal

I have the following problem. Am trying to understand how the channel block affects the input signal s(n). I know that x(n), the input signal to the filter is basically: \begin{equation} x\left(n\...
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Variable Window Size of Blackman FIR filter

I am trying to implement an FIR filter with a Blackman window function. The solution I got for my signal filtering problem is to have different window sizes for certain characteristics of the input ...
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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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Region of the coefficients of a quadratic equation that cause the roots of it to be in the unit disk

From Simon Haykin's Adaptive Filter Theory: consider the characteristic equation is $1+𝑎_1𝑧^{−1}+𝑎_2𝑧^{−2}=0$, then for the roots to be inside the unit circle (i.e. in the unit disk), the ...
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Is it applicable to implement a cascaded moving average filter with variable window on real-time?

I am using a 3-pass cascaded moving average filter for smoothing noisy data. I applied some optimization algorithms to determine the optimal length of the MAF window. For different amplitudes of data ...
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7 votes
1 answer
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Recommended Resources / Literature Search Terms for a Solutions to a Specific Kind of Multi Harmonic Signal Structure

Hopefully this isn't considered too off-topic. I'm working in industry these days and came up with a solution to a signal processing problem we'd been facing. I'd like to get a sense as to whether ...
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2 votes
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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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The Stability of the RLS Algorithm for Equalization

I am reading in the litterature that LMS is more stable than RLS. But RLS is far more faster in convergence. So my concern is how to be sure that my RLS algorithm will be stable when I am doing ...
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Droop compensation - How to do it?

Lets say i have a LPF response that has some kind of droop (some attenaution in the passband, usually could be due to cic filter how to make CIC compensation filter,,,, or can also be due to large ...
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How to design a filter that can filter out noise accurately, after setting the parameters of the filter using standard signal?

I meet a problem with designing a filter. I have two different instruments that could measure the same AC signal (usually ~200hz, always <1kHz), A and B. A can carry out signal measurement during ...
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Why does my signal magnitude increase after adaptive filtering?

I am using a series-cascade of multiple NLMS adaptive filters each with step size 0.0040, leakage factor 1.0, and 100 filter taps. My signal gains magnitude at each step of the filtering, say the peak ...
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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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Adaptive equalization vs inverse of transfer function

I have the following equalization problem as shown in the figure below: Now I can compute the coefficients for my adaptive FIR filter c (dim(c) = N) the following: $\mathbf{c_{opt}} = (\mathbf{H}^T\...
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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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Use Recursive Least Square as an "Actual" Filter?

I am currently studying recursive least square (RLS) and as far as I understand, the setup is (for example) that we are given a process with uncertain parameters/noise and we want to adapt parameters ...
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Updating forgetting factor in un-normalized lattice recursive least squares adaptive filter

The algorithms given for un-normalized LRLS and normalized LRLS filters on Wikipedia are transcribed from Adaptive Filtering Algorithms and Practical Implementation by Paulo S. R. Diniz. In reading ...
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Why can adaptive IIR filters result in unstable solutions?

For adaptive filtering, both finite and infinite impulse response (FIR/IIR) filters can be utilized. As an advantage of FIR filters in this context, guaranteed stability is often mentioned, while IIR ...
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1 vote
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Vary poles/zeros of digital IIR filter

Many applications that produce sound, such as software synthesizers, are able to apply a filter that varies with time, such as applying a low pass filter that varies with an LFO. I currently have a ...
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1 vote
1 answer
285 views

Adaptive Band pass filter for extracting respiratory waveform from accelerometer data

I am recording data from an accelerometer attached to the chest (1000Hz). I need to extract the respiratory waveform. I tried an adaptive bandpass filter based on a dominant frequency in my signal ...
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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, ...
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5 votes
1 answer
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Learning the Coefficients of Auto Regressive (AR) Model Using Least Mean Squares (LMS) Filter for Signal Prediction

I want to do two things. Estimating Coefficients of AR model using LMS Using Coefficients found in step 1 and predict future samples of a signal using AR equation. I don't have a desired signal so I ...
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Is there a noise cancellation technique for over-lapping spectra?

I understand Wiener filter is used to reduce noise, Gaussian noise as well, once we give the noise characteristic. One may derive the filter coefficient in adaptive way as well But can it remove noise ...
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9 votes
2 answers
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For complex values, why use complex conjugate in convolution?

Taken from Adaptive Filter Theory (2014) written by Haykin page 110 : $$y(n) = \sum_{k=0}^{\infty} w_k^*u(n-k), \quad n=0,1,2,...$$ where $u$ and $w$ are complex values. My question is why use ...
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1 vote
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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
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Highest rate achievable by current DSP and A/D chips?

I'm trying to determine whether an application I have in mind is feasible with currently available DSP technology (DSP chips and ADCs). I want to eliminate an interfering signal using an LMS adaptive ...
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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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1 answer
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Adaptive filter for noise cancellation when measuring some input

The context is as follows: I want to measure (as in, digitize) some input signal $x$ (I have no detailed knowledge about $x$ or its statistical description). A noise signal $x_N$ contaminates $x$ ...
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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
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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 answer
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Acoustic Echo Cancellation

I have the following diagram for acoustic echo cancellation I'm having a hard time figuring out what's present on the top and bottom lines in terms of reflected echos, original signal etc. Here's ...
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1 vote
1 answer
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Echo Cancellation over Voice Telephone Network

I'm a bit confused about the way echo canellation over a voice telephone network works like in the following figure My issue is with the fact that the point of the adaptive filter and LMS algorithim ...
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0 votes
1 answer
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System Identification using LMS Adaptive Filter

I just have a question about using an least-mean-squares algorithim adaptive filter for system identification. Consider the following I am told that as the error converges to a small value, the ...
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2 votes
1 answer
706 views

Adaptive LMS Algorithm MATLAB

I'm having some trouble implementing my LMS Adaptive Filter in MATLAB to separate wideband and narrowband signals from a voice signal. I'm using a delayed version of my input as a reference as well ...
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