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Questions tagged [frequency-response]

Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system.

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Frequency response of a rolling linear regression

I am looking for a way to characterise the frequency response of the slope from a linear regression. We are exploring the effect of window length of the regression to the magnitude of the slope of the ...
Dan's user avatar
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How to solve Hilbert Transform with empirical discrete data in frequency domain?, from zero to infinity

I have a filter/LTI system frequency response in form of list of values in the frequency domain. I want to get the phase curve/data from magnitude data. Input data can have either linear spaced points ...
Leandro Alsina's user avatar
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1/3 octave spectra from fft

I have got a signal in frequency domain. This is a frequency response function from software, so I can do nothing about it and have to leave it in frequency domain. I want to transfer the data to 1/3 ...
user2559061's user avatar
4 votes
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Digital control: Exercise solution

Can you help me (show me how) to solve the following exercise? For the process with transfer function $G(s)=e^{-2s}/(s+1)$ design a digital controller with sampling time $T_{s} = 1$ that meets the ...
Backo's user avatar
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Hints and helps to implement an accurate wavelet packet transfrom

I want to implement a Time-Freqency analysis by wavelet packets. I don't know what level and sampling rate should I use. I've tried different value for level(3,4,5,6,). but I couldn't get an accurate ...
SAH's user avatar
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2 votes
1 answer
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Help with Implementation of Transfer Function using Python or MATLAB

Relatively new to the DSP side and wanted some help to implement this approach using Python (with NumPy, SciPy libraries) or via MATLAB. Background of the problem: I'm running a linear dynamic loads ...
ganondorf29's user avatar
2 votes
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109 views

Scaling for windowed differentiator FIR filters

I recently took a dive into DSP and I was wondering what the appropriate scaling factor for a wide-band differentiator is. Let's derive the impulse response of such a differentiator. $$\begin{aligned} ...
link's user avatar
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2 votes
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Mismatch between the frequency response of a transfer function and bode plot

I generate a state space model as follows (The details are not important. This part is used to get matrix A_xi and B_xi and the state space model is xi(k+1) = A_xi*xi(k)+B1_xi*u0(k); y(k) = x(k)): <...
SoftSail's user avatar
2 votes
0 answers
251 views

DTFT and Eigenvalues in frequency domain

Consider an LTI system with impulse response $h[k]$. Does the frequency response $H(e^{j\Omega})$ equal the eigenvalue corresponding to an eigensignal of frequency $\Omega$? So if I convolve an ...
Eigenbrödler's user avatar
2 votes
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121 views

Find a LTI system such that $\mathcal{T}\{\frac{\sin t}{t}\} = \frac{\sin 2t}{t}$

Let $$x(t) = \frac{\sin t}{t} \qquad\text{and}\qquad y(t) = \frac{\sin 2t}{t}$$ Is it possible to find a LTI system such that $\mathcal{T}\{x(t)\} = y(t)$? If not, what's the reason for ...
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real refractive index from Kramers Kronig relation

I have a measurement of the complex part of the refractive index $k$ (where the refractive index is $m = n + i\,k$) measured at a nonlinear grid of wavelengths or frequencies that span several orders ...
John Smith's user avatar
1 vote
1 answer
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Signal response amplitude depends on the time interval in simulation

I have already tried to look for an answer, but I do not find existing answers satisfactory. I am interested in the absolute value of the response function of a damped oscillator (or any time series). ...
Andris Erglis's user avatar
1 vote
0 answers
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What duration of a white noise burst is required for it to be "white" at a given frequency or frequency range?

I am running white noise bursts (with very short ramps on/off to prevent discontinuities) through underdamped resonant bandpasses which are tuned to any given $f_0$ and an underdamped $Q$. Continuous ...
mike's user avatar
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Simulate Op-Amp low-pass transfer function in Python

I am struggling to simulate the frequency response of a simple op-amp low-pass transfer function in Python. The results I get are not accurate. The transfer function is $H(s)=\frac{1}{1 + s\tau}$, ...
MisterFilter's user avatar
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Z-Transform of a Precoder with XOR

I am reading a paper called "Design and Comparison of Three 20-Gb/s Backplane Transceivers for Duobinary, PAM4, and NRZ Data" and got stuck on seemingly easy thing, how the Z-domain ...
Mohamed Osama's user avatar
1 vote
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How to characterize unknown perturbations in practice ? FFT analysis?

I want to analyze the motion X(t) of a very flexible structure, which is excited/forced by unknown perturbations, in order to characterize this perturbations. Hence,...
booo's user avatar
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Adding $n\pi$ to the phase when estimating the phase velocity of a sound wave through a material

Setup I'm estimating the phase velocity in a wooden table by using an actuator and 3 sensors. The actuator sends out a chirp and on the table there are 3 accelerometers with distance $d$ between them. ...
vegiv's user avatar
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Pure Imaginary Poles (Why is it problematic?)

Consider the LCCDE : \begin{equation} \sum_{k=0}^{N}\alpha_{k}\frac{d^{k}f(t)}{dt^{k}}=\sum_{m=0}^{M}\beta_{m}\frac{d^{k}g(t)}{dt^{k}} \end{equation} Taking the Fourier transform on both sides, we get ...
CynthiaZ1998's user avatar
1 vote
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The effect of time increment $\Delta t$, frequency resolution $\Delta f$ and Gibbs phenomenon on the amplitude of the signal in the frequency domain?

Experiment: Vibration analysis (i.e.: major concern is on transfer function or frequency response). The input is an impulse (imagine as a knocking effect or knocking force), defined as a half sine ...
ComradeH's user avatar
1 vote
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The impulse response of a LTI discrete system is $h[n]=\big(\frac{1}{3}\big)^n u[n]$. Find the response of this system to the input $x[n]= e^{jnπ/4}$

Hi I'm trying to solve the problem when studying for an upcoming test. The given solution is $1.2503 e^{jnπ/4 -0.2991}$, and is found by computing $H(Ω)$ and evaluating this at $Ω=π/4$. when I try ...
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identifying overshoots in given state space system with step inputs

Suppose I have the following state space system: $$ \dot{x}(t) = Ax(t) + Bu, \quad y(t) = Lx(t), \quad x(0) = x_0 $$ where $A$, $B$ and $L$ are real matrices, $u$ is a constant real vector (so that ...
Chatter's user avatar
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956 views

How to implement a time-varying filter?

I'm working on a 10-second sound, sampled at 44.1 khz. I want to do filtering, and have a desired EQ (equalization) curve that varies over time, as suggested here (here $f0=250\ Hz$) How to ...
Basj's user avatar
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1 vote
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How to eliminate audio device transfer function from recording?

I'm working on a project which requires analysis of filter transfer function of vocal tract. The vocal tract is excited by a source signal that is a frequency sweep. The source signal is provided ...
stayl's user avatar
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Matlab's invfreqs won't fit at low frequencies

I'm wondering of anyone can explain why invfreqs() is unable to fit a polynomial to the data in the image below. The red line is the measured frequency response of an analog system. I should mention ...
CMDoolittle's user avatar
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1 answer
18 views

How to compute the 2D coordinate in the s-domain?

I am not sure if my question is a right question to ask or not since I am still learning about Laplace Transform and S-Domain. If we have 2D coordinates (x,y) in the spatial domain (i.e., Euclidean ...
S.EB's user avatar
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What kind of filter would produce this kind of frequency response?

What kind of filter would produce this kind of frequency response? I'm pretty sure there's a moving average involved, maybe two, but that's as far as I got.
adr's user avatar
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Frequency response

in 2.104 he put a condition that x(t) must be an exp to use this result ,but in 2.108 he did't even know what the value of x but use the result to get y i know that he decompose x(t) to group of exp ...
KEN Kaniki's user avatar
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What is the expected amplitude of the flat frequency response of a Kronecker delta function? Does sample rate affect it?

I was instructed here: In the sampled-time domain a Kronecker delta, $\delta(n)$, has a perfectly flat spectrum. If you look at a table of discrete-time Fourier transform pairs, this is at the top ...
mike's user avatar
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0 answers
26 views

Cutoff Frequency Calculation for Basic Multimode / State-Variable Filter

I am working with a basic multimode / state-variable filter topology which combines highpass, lowpass, and bandpass outputs. I am wondering if there is a formula I can use to calculate cutoff ...
Emmett Palaima's user avatar
0 votes
1 answer
100 views

Finding the impulse response between two microphones

I have made recordings of a single source (musical instrument) with multiple microphones and in the interest of limiting the size of the final project, I would like to find a way to get the impulse ...
arno sica's user avatar
0 votes
1 answer
183 views

How to find Gain when i have frequency of input and output signal

I need to find the bandwidth of an filter, for this im generating frequency of 1Hz to 200 hz in step of 1hz from a function generator Im expecting -3db point anywhere between 1 and 200 The output of ...
Altroz's user avatar
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0 votes
1 answer
246 views

How to determine the nature (real or complex valued) of a signal?

A signal X(t) is a real valued time domain signal and Y(t) is a signal that only contains the non-negative spectral components of X(t). How do I determine whether Y(t) is real-valued or complex? I ...
Milli_Wizard369's user avatar
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0 answers
57 views

Apply fft on video as 4D array

I working on a project called " eulerian video magnification " and i want to apply FFT on video and get the frequency response from the video . I have gotten 4D array ( frames,width,high,...
younes hajjar's user avatar
0 votes
1 answer
114 views

Cutoff frequency condition of input signal so that it can be reconstructed , given frequency response (Answer explanation?)

For the following system: We have: $$r(t) = s(t) + Ks(t-\tau)$$ where $|K|< 1$, with the following impulse response $h(t)$ and frequency-response $H(f)$: $$h(t) = \delta_0(t) + K\delta_0(t-\tau)$$ ...
cb_ann's user avatar
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0 votes
0 answers
58 views

Find impulse response and frequency response

Given $$x(n)=\left(\frac{1}{3}\right)^{n}u(n)-\frac{1}{5}\left(\frac{1}{3}\right)^{n-1}u(n-1)$$ the input to a LTI system, and output $$y(n)=\left(\frac{1}{4}\right)^{n}u(n)$$ Find impulse and ...
Chetan Fadnis's user avatar
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The frequency function for $Y_t-18=0.4X_t+0.9X_{t-1}+e_t$

I am having trouble finding the frequency function that takes me from $X_t$ to $Y_t$ in the system stated in the title. $X_t$ and $Y_t$ are stationary stochastic processes and $e_t$ is zero mean white ...
matte_studenten's user avatar
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0 answers
67 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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0 answers
34 views

IDFT of voltage frequency response of input resistance of antenna / transmission line is non causal?

Always seem to get this effect when I specifically do the real part of an input impedance over divided by the input impedance in the frequency domain: I have a lossless transmission line with no ...
Lewis Kelsey's user avatar
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0 answers
292 views

Order one FIR Filter with complex coefficient

I am trying to learn about the behavior of the FIR filter however with complex coefficients. The filter I am trying to analyze is the following: $$H(z)=a+jbz^{-1}\quad\text{where the variable}\quad j =...
chaosmind's user avatar
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0 answers
77 views

Transfer function model to frequency response

I have a problem, I wanted to filter the signal with a Butterworth filter built on the basis of a prototype. I have zeros and poles and an $H (s)$ answer, and I do not have the frequency response. How ...
Arkadiusz's user avatar
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0 answers
93 views

Why does sampling chirp at peak frequency yield correct frequency response?

Followup; setting Fs = bandWidth in accepted answer's code yields the "correct" frequency response of an LFM chirp: constant magnitude, parabolic phase. ...
OverLordGoldDragon's user avatar
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0 answers
80 views

Estimation of Group Delay from Noisy Frequency Response Measurements

Consider a linear, time-invariant system. Noisy measurements of the magnitude and phase associated with the frequency response of the system are available over some dense generally non-uniform grid ...
rhz's user avatar
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0 answers
2k views

Finding the frequency response $H(\omega)$ of a shifted sinc function

Given $$h[n]=\frac{\sin\left(\frac{\pi}{3}n-\frac{\pi}{3}\right)}{\pi n-\pi}\text,$$ use the table to find the frequency response $H(\omega)$. I don't have any clue that how to deal with the ...
keanehui's user avatar
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0 answers
219 views

How to cancel this noise to find numbers of DTMF tones?

Touch-tone telephones use a dual tone multi frequency (DTMF) scheme to encode key-presses as audio tones: I have a signal containing 10 number tones. I used frequency response to show what ...
An Vo Le's user avatar
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0 answers
233 views

Least square error channel estimation in the presence of AWGN noise

I want to implement Least Square (LS) channel estimation method in the presense of AWGN noise in MATLAB. $y(n) = x(n) * h(n)$ $Y(k) = X(k)H(K)$ Y(k) is the received signal in frequency ...
spectre's user avatar
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0 answers
87 views

Is a LTI filter completely characterized by its frequency response

I know that we use the frequency response to determine the properties gain and phase delay of a filter. However, I was wondering if this is enough for a complet characterization of the the filter for ...
rot8's user avatar
  • 101
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0 answers
228 views

Understanding the magnitude of frequency response filterbank based on elliptic filters

I've implemented a 10-channels filterbank with octave-scaled second-order elliptic filters using the Python's library scipy.signal. Here is the magnitude of the frequency response: Can someone ...
enne's user avatar
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0 votes
0 answers
202 views

system identification: MATLAB tfestimate gives different results for different Fs

So I have an experimental data; A is a chirp signal (sweep sine wave) and B is the response of the system. I identify the system as follows in MATLAB: ...
aldo's user avatar
  • 1
0 votes
0 answers
105 views

Given a log-plot of frequency-magnitude-phase how to apply it as an EQ curve to a signal?

I have several hundred data points that represents an EQ correction curve, where each point contains frequency, magnitude, and phase (-1..+1). The frequencies are distributed exponentially, not ...
James Dunne's user avatar
0 votes
0 answers
104 views

Making longer a time domain signal by adding values on its frequency domain. What am I doing wrong?

Background Here's the thing: using software for Finite Element Acoustic Simulation I got the dataset of frequency response from a room; software works by solving the wave equation in the interval $`[...
Julio's user avatar
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