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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Scenarios where Phase Response is (non-)problematic
In order to get a better feel for phase response and how it applies across the field of dsp, I'm looking for example scenarios where a filter's phase response is a concern and where it is not.
Take ...
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visualizing frequency and phase of a system's response to an impulse
Given a .wav file that is a LTI system's response to an impulse, what would you recommend as the simplest way to plot the frequency and phase output of the system? I'm already working in Python, so ...
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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 ...
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Possible error when finding group/phase delay in scipy
After designing a "least square optimal" FIR filter I wanted to find the group/phase delay, defined as: $P(\omega) \triangleq - \frac{\Theta(\omega)}{\omega}$ (Depending on the literature ...
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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,...
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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 $H(f)$:
$$h(t) = \delta_0(t) + K\delta_0(t-\tau)$$
...
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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,...
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Deducing phase from frequency response $1-z^{-1} $
In Boaz Porat's book about signal proccessing, at part 8 he mentions the example:
$$ H\left(z\right)=1-z^{-1}\Rightarrow H^{f}\left(\theta\right)=1-e^{-j\theta}=\left(e^{\frac{j\theta}{2}}-e^{-\frac{j\...
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Bode Plot - Why we add dB value in some situations?
Question: Specify the straight -line approximation of the Bode magnitude plot: $$H(j\omega) = 0.04 \cdot \frac{jw+50}{jw+0.2}$$
I don't understand that in the plotting part we add 6dB for two ...
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Inferring a response from the Analytic Signal
I have a slowly varying sinusoidal system. The output is separated using methods that produce a real signal $x(t)$ and quadrature component $y(t)$ such that $x(t)$ represents the real physical value ...
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What is the name for the technique of comparing a time domain signal to an expected signal with a sliding window?
I was trying to think about how to do time-domain analysis of a real-valued signal to determine if it contains a particular carrier. I can obviously just compute an FFT, but that transforms a window ...
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Expressing the frequency response in a more 'compact' form
I've just been working through the questions in Discrete-Time Signal Processing (Oppenheim and Schafer) and I came across this (Q33):
Consider an LTI system defined by the difference equation $$y[n] =...
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Find the impulse response of a causal 52 day moving average system to be used in stock market [closed]
Moving average system……………………….
How to solve this one?
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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 ...
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Identification of properties of a given FIR filter
I have a FIR filter which is described via following transfer function
$$H(z) = h(0) + h(1)\cdot z^{-1} + h(1)\cdot z^{-2} + \ldots + h(23)\cdot z^{-23},$$
where the coefficients have below given ...
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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. ...
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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 ...
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Why do we have a negative gain after a certain point in frequency domain for a channel filter?
Why do we have a negative gain(i.e. not negative as in polarity but gain < 1) after a certain point (1500 Hz). What is the reason and purpose for this. Why is that point the same for both DC and AC ...
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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:
$$
\hat H_{LS}[...
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Examine the operation of a filter, given its z-transform
I am given the z-transform of a filter $$H(z) = \frac{z^2 - 1}{(z-z_1)(z-z_2)(z-z_3)(z-z_4)}$$
where $z_1^* = z_2$, and $z_3^* = z_4$. I'm interested in the operation of this filter, and what happens ...
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In time series analysis, is taking a multi-period difference equivalent to a band-pass filter?
For time series, a simple high-pass filter is obtained by subtracting the previous value from each value:
$y(n) = x(n) - x(n-1)$
If I take a multi-period difference:
$y(n) = x(n) - x(n - a)$ where $a &...
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Empirical Frequency Response to test a filter function
We have a module in python that implements a digital filter. The type is not relevant. The filter coefficients have been designed to implement a particular response, but there is additional code and ...
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Matching outputs of FIR filters based on time domain convolution method and overlap-save method
I'm trying to match(to the best extent possible) the outputs of FIR filter based on Frequency domain overlap-save method and time domain convolution method resp.
I was able to get most of the output ...
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What is the optimal transient for turning on a harmonic signal with minimal bandwidth?
Given a harmonic signal of a certain frequency and amplitude, what is the optimal way of "turning on" this signal from zero to full amplitude within a given time window under the constraint ...
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Confusions understanding frequency spectrum?
I am trying to learn about frequency domain and I am using audacity software.
I selected a small YouTube video (link below):
https://www.youtube.com/watch?v=rGHrKkieqCY&ab_channel=PANKAJSAO
I ...
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FIR filter phase response at fs/2
I am currently building a FIR filter based on frequency sweeping data (0 Hz to Fs/2), i.e., transfer curve in frequency with the sampling rate of Fs.
The phase response is shown in the following ...
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Is it ok to use MATLAB ''freqs" command for Digital filters?
According to my understanding, IIR filters are somewhat analog as they are based upon analog prototypes such as butterworth,chbeyshev etc. Can we usefreqscommand to ...
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Proper notation for frequency response between $H(\omega)$ and $H(j\omega)$
Short version: which notation is formally correct between $H(\omega)$ and $H(j\omega)$?
Disclaimer: I know that no one cares in the industry. I am asking out of curiosity and care for rigorous ...
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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 ...
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IIR Filter 3dB Frequency and Amplitude and Phase of output for given input signal
I have some troubles in calculating the 3dB-Frequency and the output signal of an IIR Filter with a given transfer function
$$H(z) = \frac{1-z^{-1}}{1+0.5z^{-1}}$$
Second question is to calculate ...
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Plotting the Frequency Response of Zero-Order Hold
I'm trying to find the frequency response and the DC gain, then plot the response and find the cutoff frequency from the graph.
I start off with the impulse response
$$h(t)= 1 ; 0\leqslant t\leqslant ...
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Why don't unit circle poles lead to infinite amplitude response for Butterworth lowpass?
This is probably a very stupid question. In many places (e.g. here), the Butterworth filters, e.g. lowpass, are described as being "allpole" filters, that have all of these poles on the unit ...
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How does signal subtraction affect frequency response?
I had a noisy signal which I denoised using machine learning. Now assuming the noise was additive I am subtracting the denoised signal from the noisy signal to get the noise part. I just did time ...
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Advantages/disadvantages of impulse excitation vs step excitation
i'm currently working on a circuit transient simulation, and I'm wondering how the type of input excitation can affect the final result. In particular the focus is on impulse input vs step input, to ...
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Representing changing sample rate in block diagram and frequency response plot
I have an discrete integrator which sums over a block of input samples to produce output samples at a lower rate.
The integrator sums a block of 8 input samples, multiplies the sum by a coefficient, ...
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plot the frequency responce of a sos Analog chebychev filter using python
I am new to signal processing.
I am using an sos analog Chebychev filter, and I was wondering what would be the result of plotting its frequency response using the ...
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How to calculate impulse response from frequency response whose denominator has an imaginary roots
It is quite easy to solve when the denominator of the frequency response has no imaginary values..... But I do I solve something like this?
$$H(\omega)=\frac{1+2e^{-2j\omega}}{1-\frac{1}{15}e^{-j\...
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Computing the frequency response using fourier transform of an unstable LCCDE system
Given LCCDE system. Is it possible to calculate the frequency response using Fourier transform?
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Converting signal to frequency domain then back to time domain - noise issue
I am trying to convert a signal into frequency domain using fft then construct a time domain signal (with any length) from the frequency response. With my matlab code, it works fine when there is no ...
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IDFT of voltage frequency response of input resistance of antenna / transmission line is non causal?
Always seem to get this effect when I specifically do the real part of an input impedance over divided by the input impedance in the frequency domain:
I have a lossless transmission line with no ...
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What metrics should I use to describe the difference between two magnitude responses in octave band
Suppose that I have two frequency responses $H_1(k)$ and $H_2(k)$, I want to describe the difference or MSE between them in each octave band. The background is that I have a target frequency response $...
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Proving Fourier transform of cosine multiplied with another function
Cheers, I have a impulse response that looks like this: $h(t) = h_1(t) \cdot \cos(8 \pi t)$ and I have to find its frequency response. In order to achieve this I am trying to use the fact that $$x(t)y(...
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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 ...
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Drawing phase of frequency response with phase $e^{j\frac{\pi}{2}}$
Cheers, I have a response function of: $$H(\omega) = \begin{cases} \frac{1}{2}j\omega, |\omega| < \omega_c \\ 0, \text{elsewhere}\end{cases},$$ and I am asked to find draw its magnitude and phase. ...
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Can someone explain why signal.freqz() generates a different phase in the frequency fresponse than scipy.signal.dfreqresp()?
I have been using scipy to analyze filter performance for a single-pole IIR filter, and I noticed a disagreement between the phase in the outputs of the freqz() function compared to the output of the ...
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Getting phase response from magnitude. How to develop and solve this Hilbert transform?
I'm trying to generate phase data from magnitude data in a frequency function, assuming the system is minimum phase. Using Hilbert Transform.
For instance, having this simple system:
$G(s) = s$
$G(j\...
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If i have arbitrary complex number what is the best method to make filter
i have equation like for example A(W) = isin(2pi*w) in frequency domain (it can be anything)
that have arbitrary amplitude and phase response.
i usually make symmetric structure in real part and ...
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What is The Fourier Transform Formula for 1/(j*pi*t) Types?
I have old homework and solution of that but i didn't understand actually solution. Because i didn't see continous-time fourier transform formula for that.
$g(t)$=$\frac{1}{j\pi*t}$ and it asks ...
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Arbitrary shape frequency response filter [duplicate]
i want to make arbitrary shape digital filter from equation. that have own magnitude and phase response.
the equation is bessel function. the frequency response is below zero phase and real value
and ...
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