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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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Compensating Loudspeaker frequency response in an audio signal

I have been working on a project in which I was required to work on the audio signals recorded from the loudspeaker kept in front of a filter. So, to simply explain it: $$\boxed{\rm LoudSpeaker} \...
Styal's user avatar
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How can I plot the frequency response on a bode diagram with Fast Fourier Transform?

Assume that we have an unknow dynamical system and we only want to estimate its parameters. The system can be discribed as: Continous time: $$G(s) = \frac{3s + 5} {5s^2 + 3s + 2}$$ Discrete time ...
euraad's user avatar
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What is meant by a system's "impulse response" and "frequency response?"

Can anyone state the difference between frequency response and impulse response in simple English?
Ant's's user avatar
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3 votes
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Berchin's FDLS arbitrary filter design algorithm

I'm trying to use Berchin's FDLS methods (for those that don't know what it is, it's a way to design arbitrary magnitude and phase of an IIR Eq) I tried different things but neither gave me what i ...
ion_one's user avatar
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For 2D signals can it be said that the frequency response is the same as the Fourier transform?

Say I have a signal: [1, 1 , 1; 1 100 1; 1 1 1];, I wanted its frequency response, then can I take its FFT? Why does MATLAB have two functions to do the same ...
user26763's user avatar
20 votes
3 answers
35k views

How poles are related to frequency response

I have recently fallen into fallacy, considering pole s=1 as there is infinite response at frequency 1. Yet, response was only 1. Now, can you derive the frequency response, given the poles? ...
Val's user avatar
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Design a linear-phase FIR filter approximating the magnitude of a given IIR filter

I have a biquad IIR filter from which I want to get a linear-phase FIR. I saw that related question but the OP does not care much about phase. I have troubles getting the exact same magnitude curve ...
filaton's user avatar
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Discrete-time Biquad filter: Relation between peak frequency and pole frequency

This question arose from a discussion in the comments to this question and its answer. The author of that question discussed a discrete-time second order filter described by the following difference ...
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Understanding the H1 and H2 estimators

So the $H_1$ and $H_2$ frequency response estimators for SISO systems are defined according to: \begin{align} H_1 &= \frac{P_{yx}}{P_{xx}}\\ H_2 &= \frac{P_{yy}}{P_{xy}} \end{align} Where $\...
Pontus S's user avatar
3 votes
2 answers
10k views

How frequency response related to a transfer function

Can anyone explain how frequency response related to a transfer function?
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How to estimate a transfer function from a magnitude-only frequency response?

Given an arbitrary frequency response, what signal processing methods might exist that could guess, estimate or determine a transfer function (pole and zero constellation) which gives a "reasonably ...
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Design of a digital A-weighting filter with arbitrary sample rate

I want to A-weight a time series with arbitrary sample rate. An analog A-weighting filter is defined exactly by IEC 61672-1. But there's no definition for a digital filter. One method is to use the ...
user2561747's user avatar
4 votes
1 answer
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Frequency response of $\mathrm{sinc}[n]$

In this image the frequency response of a discrete time filter given as $h[n]$. Can someone explain how the magnitude of the frequency response is found ?
Jawad's user avatar
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Frequency response equivalent to characterise transient response (to sinusoidal inputs)?

I am interested in characterising the time-dependent response of a system to a sinusoidal input. The steady state response of the system is also sinusoidal, however I wonder if there is a standard ...
xyz's user avatar
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How to stabilize a filter

Suppose we have an unstable all-pole filter with transfer function $H(z) = A(z)^{-1}$. What is the best way to design a stable filter with frequency response as close to that of $H$ as possible. (I ...
sarasvati119's user avatar
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311 views

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
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Magnitude value of filter frequency response

Can someone help me with this problem: Suppose we filter signals with the below pre-emphasis filter: $$y[n]=x[n]-0.8x[n-1]$$ I have to calculate the impulse response of the filter (ok easy) and ...
Ewan Terry's user avatar
2 votes
3 answers
2k views

Does chirp have constant magnitude frequency response?

Pg. 223 claims so, yet my results via DFT differ: Is the textbook wrong? My attempted explanations: (code) DFT vs DTFT: "frequency response" is computed via latter. Still, DFT should ...
OverLordGoldDragon's user avatar
2 votes
1 answer
774 views

Design Lowpass Filter With -7.5 dB/Octave Rolloff

I am working on a project that needs a lowpass filter with a -7.5 dB/Octave rolloff. This is somewhere between the rolloff of a one-pole and two-pole filter, so I wanted to ask what some standard ...
Emmett P's user avatar
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1 answer
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Adding phase noise to a signal results in amplitude variation on a constellation - whats the mistake? *plots inside*

I am attempting to add phase noise to a modulated signal. I am doing this by taking a phase noise mask (single sided 0 Hz to 1 MHz), which shows dBc values away from central value or reference value. ...
Villere_DSP's user avatar
1 vote
1 answer
807 views

How to estimate the delay in time domain when knowing the phase shift in frequency domain

I am strugling with how to compute the exact value of delay in time-doamin when knowing phase shift in frequency domain. I have a analog circuit, I sweeped about 30 single tones frequency ranging from ...
user190055's user avatar
0 votes
1 answer
81 views

frequency sampling method) why the coefficient is not symmetric?

Here is matlab code ㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡ ...
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Find Magnitude Responce at $\omega=\dfrac{\pi}{2M}$ where $M$ is the number of channel in QMF

I have frequency response of low pass filter ...
Rajat Sharma's user avatar
0 votes
1 answer
521 views

Custom nearly-linear-phase IIR filter computation gone wrong

I'm using the code in this book: Algorithms for the constrained design of digital filters with arbitrary phase and magnitude responses to compute nearly-linear-phase IIR EQs. ...
ionone's user avatar
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-1 votes
2 answers
143 views

Frequency response using fourier

i need to find the frequency response of the following equations: $$h(t) = e^{-3t} u(t)$$ $$x(t) = 1+\cos\left(\frac{4\pi}{3}t\right)$$ find $y(t)$ However i am quite confused on how to do this, ...
user998316's user avatar
12 votes
1 answer
3k views

Approximating the frequency response of a median filter

A median filter is a non-linear and lossy process, so it doesn't have a closed form frequency response as would a FIR filter (say a box filter of the same length) in an LTI system. But how closely ...
hotpaw2's user avatar
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11 votes
4 answers
21k views

For an LTI system, why does the Fourier transform of the impulse response give the frequency response?

I know that for a given system, the Fourier transform of its impulse response gives its frequency response. I want to find where this property comes from, but haven't been able to find if it's a ...
Florian Castellane's user avatar
9 votes
1 answer
7k views

Plotting the magnitude response of a biquad filter

I've put together a multi-band audio EQ using biquad filters. I'm getting the coefficients using the methods from the RBJ cookbook. Now I want to plot the curve showing the magnitude response. I'm ...
MVTC's user avatar
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6 votes
1 answer
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What exactly is Savitzky-Golay differentiation filter?

I could understand Savitzky-Golay filter as being smoothing filter, but then there also seems to be Savitzky-Golay differentiation filter, though for some reason, details do not seem to be clear. So ...
user8059's user avatar
5 votes
1 answer
625 views

Understanding the $\mathcal Z$-transform

I was studying $\mathcal Z$-transforms and found pretty good material on the topic, though I feel I do not have a proper understanding of the concept. Could someone help me clarify this? I know that ...
Nbk's user avatar
  • 53
4 votes
2 answers
2k views

Correcting phase response of a signal

I have a sensor that applies a frequency dependant phase alteration to my signals. I'm trying to find a way to correct these phase responses using an FIR filter. Essentially, I'm looking for methods ...
RTbecard's user avatar
  • 189
4 votes
1 answer
448 views

Why is $y(n)=x(n)-x(n−1)+x(n-2)$ a low-pass filter?

I know that it's a low-pass FIR filter with impulse response of length equal to $3$, but I don't know how to explain exactly why it's low-pass.
Elle Oliver's user avatar
4 votes
0 answers
7k views

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
1 answer
1k views

System identification/ Filter estimation to mimic frequency equalizer of audio with Scipy

At the current problem I'm working on, I have two signals: One "original" signal that contains audio (voice). The second signal is the same audio file but edited with a frequency equalizer, for ...
Jamona's user avatar
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3 votes
1 answer
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Nyquist Plot for transfer functions with poles at the origin

I'm learning Nyquist plots and something has been seriously bugging me when treating poles or zeros in the origin. Nyquist plots obtains information based on the argument principle which states "If f(...
Colin Hicks's user avatar
3 votes
2 answers
2k views

The frequency response function (FRF) fails to detect the antiresonance of a system

I am trying to identify a vibrational systems by computing the frequency response function (FRF) of the system when a chirp signal is applied to its input. After comparing the FRF computed and the ...
Juan Carlos Ibáñez's user avatar
3 votes
1 answer
2k views

Calculation frequency response of digital filter with known structure

Short question What are main stages (steps) of calculation frequency response of digital filter by their structure? Detailed question Let suppose that there is discrete FIR filter with known ...
Gluttton's user avatar
  • 388
3 votes
1 answer
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Difference between $\tt freqz()$ and $\tt plot(abs(fft()))$ in MATLAB

I've plotted the response of a high-pass filter x=[1 -1]; freqz(x) gave me where as the magnitude plot for the ...
phanitej's user avatar
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3 votes
3 answers
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Determining output of a LTI system

Consider following LTI system $$y[n] - 2y[n-1] = x[n]$$ where $x[n]$ is the input to the system and $y[n]$ is the output. Let $x[n] = \cos[n\frac{\pi}{3}] + 2\cos[n\frac{\pi}{2} + \frac{\pi}{4}]$, ...
S.H.W's user avatar
  • 726
2 votes
1 answer
384 views

Why does this transfer function estimation not work? System identification

Goal: I have an unknow dynmical system $G(s)$ and I want to find it from measurement data, output $y(t)$ and input $u(t)$. The data is frequency responses. Method: I begun first with creating the ...
euraad's user avatar
  • 405
2 votes
1 answer
293 views

Computation of parameter filter to match a given frequency response

I'm looking for the practical way to compute the parameters ($a_1$, $a_2$) of a digital filter to match a certain frequency response. I'm studying the 12-poles filter of the vintage component SP0256 ...
Robert Dawson's user avatar
2 votes
1 answer
2k views

How do bode plots work with unstable systems work?

If I had a system with right-half s-plane poles, how would a frequency response work? Since a purely imaginary value for s, would cause the Laplace transform to diverge for such a system, what meaning ...
Colin Hicks's user avatar
2 votes
1 answer
540 views

Plot the frequency response of MTI delay line canceller using Octave

I try to plot the frequency response of the delay line canceller (FIR filter which used for MTI). The delay line canceller has the following structure: ...
Gluttton's user avatar
  • 388
2 votes
2 answers
357 views

Frequency-domain deconvolution

I want to estimate the impulse response of an LTI system using frequency-domain deconvolution. Suppose that the input signal $x[n]$ of length $N$, and the unknown system impulse repsonse $h[n]$ of ...
DSP novice's user avatar
2 votes
3 answers
3k views

getting frequency response from input and output signal

How does one get the frequency response of a filter, given an input signal and the signal output by the filter?
svdotbe's user avatar
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1 vote
1 answer
115 views

Impulse response and amplitude-frequency characteristic of a communication channel

The task is to implement communication system for transmission of 32 multiplexed signals through communication channel represented by copper cable whose frequency characteristic is given by: $$H(f) = ...
3d014's user avatar
  • 15
1 vote
1 answer
720 views

Negative instantaneous frequency with hilbert transform using scipy hilbert

When I produce a chirp signal with a duration of 2 sec, sampling frequency of 200Hz, with frequencies ranging from 20Hz-100Hz, I get negative instantaneous frequencies using the scipy(Python) Hilbert ...
curious individual's user avatar
1 vote
4 answers
1k views

What is the correct gain of an RRC Filter?

Breaking my brain all morning with this reading previous questions and googling ... I have made an RRC filter from the equation on wikipedia. It works fine and I compared it to commpy library in ...
Natalie Johnson's user avatar
1 vote
1 answer
73 views

Inferring a response from the Analytic Signal

I have a slowly varying sinusoidal system. The output is separated using methods that produce a real signal $x(t)$ and quadrature component $y(t)$ such that $x(t)$ represents the real physical value ...
Eli S's user avatar
  • 131
1 vote
1 answer
764 views

How to prove these two definitions of the minimum phase transfer function are same?

There are so many definitions of the minimum phase transfer function, and these are two of them. The transfer function of the system which has no zeros or poles at right half plane. The transfer ...
Kim Jaewoo's user avatar