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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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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1 answer
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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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1 answer
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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 ...
3 votes
2 answers
197 views

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 ...
2 votes
2 answers
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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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1 answer
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IIR Filter 3dB Frequency and Amplitude and Phase of output for given input signal

Hi I have some troubles in calculating the 3dB-Frequency and the output signal of an IIR Filter with a given transfer function $H_Z = \frac{1-Z^{-1}}{1+\frac{1}{2}Z^{-1}}$ Second question is to ...
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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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1 answer
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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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Python Bode plots frequency response of transfer function

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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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1 answer
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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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1 answer
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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 ...
1 vote
1 answer
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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 $...
3 votes
2 answers
166 views

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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1 answer
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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. ...
1 vote
1 answer
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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 ...
5 votes
1 answer
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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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frequency sampling method) why the coefficient is not symmetric?

Here is matlab code ㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡㅡ ...
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Estimating change in RMS of noise given FIR filter coefficients

Filtering noise leads to a change in the overall RMS of the noise as demonstrated by the following code-block. which uses scipy's firwin2 to calculate the taps. The ...
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1 answer
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Combining multiple bandstop filters works only sometimes

for a school project, we were supposed to filter out 4 rogue cosine waves of a given frequency. I created a filter of my own by choosing zeroes and poles by hand. Here, I made 4 poles and 4 zeroes (...
2 votes
3 answers
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Create filter without regard to phase response (amplitude only)

Why I only care about amplitude response I'm working on equalizing a DAC where I only care about the flatness of an AWGN spectrum. Since AWGN has random phase for any frequency bin, I do not care ...
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Frequency response of an ideal low pass filter

I have an ideal low pass filter having unity gain and cutoff frequency 100Hz. If I provide an input having single frequency component at 100Hz(E.g.- cos(200pi t), will the low pass filter block the ...
1 vote
1 answer
118 views

Measure Frequency-Response of Sensor using a Signalsource and Reference-Sensor

Cheers, I want to measure the frequency response of an acceleration sensor. I have: A signal source (device similar to a loudspeaker that shakes the acceleration sensor), of which I do NOT know the ...
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2 votes
2 answers
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Measuring the frequency and impulse response of an audio recorder

I would like to test the frequency and transient/step response of the Zoom H5 recorder preamps. If possible, I'd also like to test the preamps for the built-in (exchangeable) XY capsule module, but I'...
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How are pole-zero plots, magnitude response plots, and phase response plots related?

Given that the Laplace transform of a continuous-time signal $h(t)$ is $H(s)$, what can a plot of the poles and zeros of $H(s)$ on the $s$-plane tell me about the magnitude response and phase response ...
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Why does the Superheterodyne AM Receiver use an envelope detector?

I'm currently learning about the Superheterodyne AM Receiver and I don't understand why does it use an envelope detector (as suggested here) rather than taking the signal back to its baseband ...
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How to get the difference equation from impulse response?

I'm trying to solve a problem about filter design. We want to design a equalizer filter which have the following frequency response : How can i get the difference equation from the impulse responce ...
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1 answer
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How to calculate signal after passing through the filter?

I have the amplitude response of the LPF (here it is generated in Python): ...
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Log Path Loss Model with Directivity Accounted

Suppose that I have the log Path Loss distance model described here https://en.wikipedia.org/wiki/Log-distance_path_loss_model $$PL(d,\gamma) = P_{t}-P_{r}=PL_{0}+10\gamma log_{10}\frac{d}{d_{0}}+X_{g}...
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what are the application of fourier transform in finding frequency response? [duplicate]

i need the application of Fourier transform in finding frequency response in mathematical terms
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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)): <...
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How to properly band-pass filter an autocorrelated signal?

Let's consider an example ECG time series, sampled at 360Hz: I verified that autocorrelating a signal preserves its frequency content. For instance, both original and autocorrelated data show the ...
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How to convert passband and stopband frequencies to poles and zeros

I have a NI 9229 digitizer with the following datasheet. The datasheet mentions: a passband frequency of $0.453f_s$ with a flatness of $\le0.1\,\text{dB}$ a stopband frequency of $0.547f_s$ with ...
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Fine tuning LPF responses from cascading APFs

I would use this post to outline my question since the post had laid down the groundwork: how to design LPH and HPF from APF So if want to fine tune overall LPF response with more cascading allpass ...
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2 answers
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Design of all pass filter with desired phase response

I want to design an all pass filter with a desired phase response in MATLAB. But in MATLAB, all pass filters are designed either by specifying the all pass filter coefficients or from a transfer ...
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Design of digital filter with desired phase response

I want to design a digital filter with the following phase response in MATLAB. i.e. at 1kHz, the phase response should be 9 degrees, at 2khz phase response should be 18 degrees ,at 3kHz phase response ...
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Z domain Transfer function to magnitude

How would one go about calculating the Magnitude of... $\mathcal{Z}$-transform = $$\frac{1}{1-z^{-2}}$$ I understand that z can be replaced with $${exp}^{j\omega}$$ and I am aware of the identities $${...

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