Questions tagged [frequency-domain]
The frequency-domain tag has no usage guidance.
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IFFT confusion, sampling frequency
I made a previous post about what I am trying to do
Previous Post
I have band-limited data in the frequency domain from a VNA and I am trying to convert it into the time domain. VNA data saved in .s2p ...
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Why do we calculate the second half of frequencies in DFT?
As far as I know, for any signal the first $N/2$ frequency samples and second $N/2$ frequency samples are equal (by magnitude), so (sorry, if I made mistake in indices):
$$X[k]=\sum_{n=0}^{N-1}x[n]e^{-...
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Why does interpolation with zeros introduce frequency artifacts?
Consider the original signal (just a sine) and the same signal interpolated with zeros:
The Fourier transform of them:
In this example I inserted only one zero between the samples, as if I sampled ...
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FIR filter design using DFT matrix inversion
In my previous question I use a system identification case as an example. Here I came across another question. I want to design a FIR filter of length $L$ to equalize an LTI system whose impulse ...
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How to remove PWM cycles present in a signal?
I have applied PWM across a DC motor. The voltage measured across the motor is shown above.
I want to count the ripples present in the data. The ripples exist at a different frequency than the PWM ...
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How do I determine how many noise components are numerically contained in the Wavelet Transform Image?
How do I determine how many noise components are numerically contained in the Wavelet Transform Image?
I used Matlab's DWT2 to convert the wavelet to check the vertical, horizontal, and diagonal noise ...
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Causality of an estimated filter
Assume $\tilde{h}(f)$ is a filter estimated by an algorithm for (room) impulse response estimation working in the frequency domain.
Is there a way to assert if such filter is causal?
Specifically, ...
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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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Constellation Mapping In OFDM
If i am not mistaken, the two following hold :
a. In OFDM Conceptualization, the constellation mapping at Tx (or de-mapping at Rx) is done in Frequency domain
b. However the basic theory (Including ...
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Calculating SNR of one N-point DFT over another M-point DFT in frequency domain
Consider N-point sine signal mixed with a random noise (implemented in Python below):
...
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Extract the Frequency from the Index of the Bin in 2D DFT
How can I find the distance from DC term (center) to the peak point of the frequency in the image Fourier transform?
In the figure below, we know that the distance of the peak point goes to the edge ...
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How can you get the mean wavelength/frequency of a Discrete Fourier Transform (DFT)?
I am very new to the concept of Fourier transforms and DFTs so please explain in as simple terms as possible.
I am messing around with Fourier transforms in processing. I wanted to determine the ...
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frequency Domain with bandlimit
May I ask why does the frequency Domain Picture of a signal look like that? Is the signal built with many different frequencies?
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Frequency domain equivalent to center oriented rotated convolution?
I have a convolution kernel which I need to apply to an image. However, at each pixel in the image, I'm convolving using a rotated kernel, with respect to the center (think hands on a clock, with the ...
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Frequency difference measurements
I am trying to find the frequency difference ($\Delta f= f_1 - f_2$) between two complex sinusoidal signals using Matlab. The two signals are:
$$r_1 (t)= A~ e^{j 2 \pi f_1 t}= A \cos(2 \pi f_1 t)+j A\...
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Detecting and Removing Noise from Signal using Python
Through this platform, I want to ask that how can I remove unwanted noise from the signal when you do not have much information regarding the frequency at which they appear? Data is collected from an ...
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Need help with DTFT problem
Prepping for exam and this is one of the practice problems:
I just want some clarification on some of the steps my professor took. This is the answer in the answer sheet
Only thing I dont understand ...
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S domain vs frequency domain?
Laplace domain is also known as "s domain".
Is there any difference between "s domain" and "frequency domain"? Can we use both terms interchangeably?
If we want to ...
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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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Analytical derivation of convolution and multiplication implement of time-domain signal
I have a system model as shown in figure 1. I want to change the model to a new schematic as in figure 2. How to analytically derive the filter $H_2$ if all parameters are known?
I guess that we will ...
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What is the maximum possible frequency of human voice/speech(That can be generated through human vocal cords)?
Human hearing range is commonly known to be 20 Hz to 20 KHz
But what about speaking range? We know that speech Sounds are generated through our vocal cords. So What is the maximum value of frequency ...
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What is the frequency representation of nonuniform sampling?
Uniform sampling can be thought of as multiplication of a function $x(t)$ with a Dirac comb function: $$\text{III}_T(t) = \sum_{k=-\infty}^{\infty}\delta(t-kT)$$
Multiplication of $x(t)$ with $\text{...
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Multiplication in frequency domain for a signal containing a whole frequency spectrum
Imagine we have two signals in the frequncy domain X(f) and H(f), for one of the signal H(f) I have the complex pair and the frequncy at which that complex pair exists. The second could be any random ...
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Does LPF limit the maximum sampling frequency of the input signal? [closed]
Consider the system where the signal passes through analog LPF with cutoff frequency of 50 Hz, so the maximum sampling frequency of the input signal could be 100 Hz (according to the theorem). But can ...
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Phase extraction from Fourier transform
Is it possible in principle to correctly extract the phase from Fourier transform?
I just tried to do so using Python, here some attempts:
...
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Bandwidth visualization in frequency domain
Consider some signal in frequency domain:
the maximum length of which corresponds to the half of the original signal ($N/2$), here $N=32$.
It is known that the bandwidth of each sample is $2/N$, so ...
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mp3 encoding in the frequency domain
Let's start with an arduino signal, which can be periodic over time. When this signal is converted from analog to digital it "turns" into a series of bits. At this point, is this signal in ...
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Plot Power Spectrum of Noisy Image in Python
I've been asked to plot the power spectrum of an image where I added Gaussian noise to it. However, I am very new to Image Processing so I don't know exactly how to approach my problem.
I calculated ...
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FFT and spatial frequency basic knowledge
Using the following website: on how the Fourier transform works (Interested in the Basic Principle part). I found out that if you have 3 pixels closer in the spatial domain you'll get more spaced ...
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Frequency filtering in the frequency domain vs. time domain
As a DSP newbie, I've stumbled into doing band pass filtering (of pre-recorded IQ data) in the frequency domain - which allows brick wall filtering (I'm just setting the IQ values of each consecutive ...
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Power spectral density and auto correlation function: Frequency vs time representation
I have a time correlated periodic signal $a(t)$ with $t=0,1,...,T$ and $a(t+T) = a(t)$ that has been sampled at rate $\Delta t$ and I analyse the signal using the PSD via FFT and the ACF. As far as I ...
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Sinc Based Multi Dimension Signal Resampling on the Fourier Spectrum (DFT)
As a generalization of the following questions:
The Proper Way to Do Sinc Downsampling (DFT Downsampling) for Uniformly Sampled Discrete Signals with Finite Number of Samples.
The Proper Way to Do ...
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Applying 2D Sinc Interpolation for Downsampling in the Fourier Domain (DFT / FFT)
Related to The Proper Way to Do Sinc Downsampling (DFT Downsampling) for Uniformly Sampled Discrete Signals with Finite Number of Samples, how can one apply Sinc downsampling in the DFT / FFT domain ...
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Applying 2D Sinc Interpolation for Upsampling in the Fourier Domain (DFT / FFT)
Related to The Proper Way to Do Sinc Upsampling (DFT Upsampling) for Uniformly Sampled Discrete Signals with Finite Number of Samples, how can one apply Sinc upsampling in the DFT / FFT domain for a ...
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Real time signal processing in frequency domain
i'm doing realtime signal processing simulation.
it could be simple question.
if i multiply input L sample fft and M block filter in frequency domain and i do ifft
the output come out when index is L+...
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non-causal cascade filtering process in frequency domain
if i have linear filter that operate in frequency domain filter length is L
(Overlap and save method)
if there is no computational time, i get L input signal and fft and multiply filter and ifft
the ...
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overlap save method zero padding fft gibb's phenomenon
i'm doing overlap save method in frequency domain. i make hankel function to digital filter using frequency sampling method(to make arbitrary magnitude phase filter). and i do ifft and zero padding ...
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Fundamental Frequencies of different instruments
I'm trying to study what differentiates different instruments in terms of frequencies, timbre, etc.
By studying a few different samples of notes, I've come to the conclusion that for flutes the ...
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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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Analytic image using 2-D Hilbert transform
I am working on a problem of phase (/phase derivative) retrieval from closed fringe patterns. The paper https://opg.optica.org/ao/fulltext.cfm?uri=ao-58-16-4420&id=413113 which uses a pseudo-...
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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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cascade and summation process in frequency domain using overlap and save method
hello i'm doing signal processing like this
S : FFT of input signal from microphone
Exp : just gain
1/(Q*J) : include frequency component, I convert this equation to frequency domain digital filter ...
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2D Spatial Fourier Tranform on a pressure field
I'm doing some research on Fourier Near-field Acoustic Holography (NAH). The basic theory behind Fouerir NAH is that you take a sound pressure field measurement in a 2d plane p(x,y), 2d spatial ...
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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 ...
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Relation of zero-padding and frequency resolution
Consider simple rectangular pulse and FFT of it in Python:
...
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Frequencies calculation of discrete signal in frequency domain
I have some misunderstanding in definition of frequency resolution of the signal. Here it is assumed that the resolution is: $$\hat{f_k}=f_{signal}\cdot T_{sampling}$$ (which is just relation of ...
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The Proper Way to Do Sinc Upsampling (DFT Upsampling) for Uniformly Sampled Discrete Signals with Finite Number of Samples
Given a signal $ \left\{ x [ 0 ], x [ 1 ], ..., x [ N - 1 ] \right\} $ what would be the correct way to upsample it in the frequency domain (Sinc interpolation)?
Note: Added as a request by the answer ...
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Removing Attenuator and Real Mixer influence on the received Baseband signal in Radar IQ Transmitter - De-embedding
Radar IQ Transmitter Measurement Setup:
Waveform Generator + IQ Transmitter + Attenuator + Real Downconversion mixer + Oscilloscope + Post-processing (Hilbert Transform)
With the above arrangement ...
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When if an FFT more efficient than Goertzel?
Given a block, $x[n]$, of M samples.
Calculating abs(fft(x)).^2 returns the power spectrum of that block through the use of a $M$-point FFT.
I can calculate the same using Goertzel's algorithm.
At ...
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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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