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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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:
$$H(f) = ...
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Finding the impulse response between two microphones
I have made recordings of a single source (musical instrument) with multiple microphones and in the interest of limiting the size of the final project, I would like to find a way to get the impulse ...
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Z Transform and Difference Equation [closed]
Given that
$$H(Z) = 4z+2/(4z^2+2)*(2z-1).$$
Find the difference equation of g(n) such that g(n) and h(n) are two cascading filter such that output is same as input. Moreover find the frequency ...
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low shelving filter frequency response diagnosis
I am building a second order modified biquad filter based on an implementation by Will Pirkle in "designing audio effect plugins in c++". However when I look at my implementation's ...
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Characteristics of linear systems in the time and frequency domain
Why is the output signal obtained through frequency response different from the other two.
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Finding phase of frequency response as a function of frequency
I am trying to calculate manually the phase of the frequency response of an LTI system as a function of frequency and plot the results. The original system is described as $y[n]=0.1(x[n]-x[n-1]+x[n-2]$...
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IFFT caused inverted phase
I've created ifft of signal:
Wf=[0 zeros(1,19) conj(W) zeros(1,6000) flip((W)) zeros(1,19)];
w=real(ifft(Wf));
Now take a look ...
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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 ...
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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}$, ...
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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 ...
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Sine as input to an LTI system
Everywhere in theory (books , online) there is this statement "For sinusoidal inputs, any LTI has a sinusoidal output with the gain of $|H(s)|$, the same frequency, and a phase shift equal to $\...
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How can I convert a 1/3rd octave spectrum into a linear spectrum for use as a frequency response?
I have a one-third octave spectrum with 23 frequencies, and I want to use it as a frequency response to filter another spectrum, however that spectrum is specified linear with 2049 points.
I know I ...
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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 ...
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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}
...
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Computing frequency response of a filter given Z-transform
I am currently working on a project that involves analyzing the frequency response $H(e^{j\omega})$ of the filter $H(z)= \frac{1}{2} (1+z^{-1})$. However, I am unsure about the specific steps and ...
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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 ...
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Peak locations in Hz with findpeaks() (log spaced bins)
I have resolved peak locations using Octave findpeaks command:
...
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How to match coefficients of a SVF compared to Biquad in order to Plot the frequency response?
I'd like to output the frequency response of this filter.
Here's how the coefficients are calculated:
...
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Frequency response measurements by audio signal FFT
I am trying to measure the frequency response of different audio canals, e.g. tubes, hollow pipes etc.
My experimental setup looks like this: I generate an audio signal with a loudspeaker (Visaton WS ...
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can I calculate freq response generically from filters?
I'd like to display the freq response of a Sallen Key filter type (in the specific case, this simple resonant filter).
on biquad, for example, I calculate magnitude and phase from zeros and poles, ...
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Improving Modeling of Thermal Noise Behavior at Antenna
Background
I recently asked this question over on Electrical Engineering Stack Exchange. On the advice of some commenters there, I've broken off those pieces which are appropriate for asking as ...
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Getting different results when fourier transforming in python vs mathematica?
I am interested in troubleshooting why I get a very different answer when doing fourier transforms of my data in Mathematica vs Python. The version in Mathematica is well behaved, yet all versions of ...
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Need to make audio human listenable
I wrote some golang code which implements 3Blue1Brown's Hilbert's Curve: Is infinite math useful? ... give the code an image and it returns back its audio equivalent ( inverse Fourier Transform ) ......
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How to compensate phase delay introduced by the digital integrator?
Let's say I have a digital integrator with transfer function in following form
$$
\frac{Y(z)}{U(z)} = \frac{T}{2}\cdot\frac{z + 1}{z - 1}
$$
I have been looking for a mechanism how to compensate the ...
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Lomb-Scargle negative power and Response time
I have response time (RT) data (values between 0 and 3) to a memory task. Participants made a response at about every 9.5sec with several breaks of 25sec. I want to analyse the whole timeseries of (RT)...
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Frequency response of an LTI system described by the diagram below
I am trying to solve the below problem:
To begin with the frequency response of the ideal low pass filter with $\omega_c= \pi/4$ is given by $$
H(\omega) =
\begin{cases}
1 & \text{if -$\pi/4$ $...
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Why is an imaginary part in the output of my time-domain resposne of real input?
I have measurements of a transfer function $H(f)$ in the frequency domain between 1-6 GHz. I also have an input signal, which is pulsed chirp $x(t)$. The goal is to build the time-domain response of ...
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Real & Imaginary part of the frequency response of LTI system
I am looking at the H(f) which is the frequency response of an LTI system. What kind of relationship should I expect between the real and imaginary part of this frequency response? Here is an example ...
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How to process a signal in frequency domain then convert it bakc to time domain?
Maybe a example of coupling effect in frequency modulated continuous (FMCW) radar will be helpful to better demonstrate my problem.
Let us consider a FMCW radar system. We have a complex transmitted ...
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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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