Questions tagged [frequency-domain]
The frequency-domain tag has no usage guidance.
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What does the frequency domain of bipolar Alternate Mark Inversion (AMI) look like?
Someone said to me that Bipolar AMI is not low-pass; it does not include the 0Hz in its frequency domain. I doubt that that is the case.
However, at present I am unable to do Fourier transformations. ...
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Filtering in time domain vs filtering in frequency domain
The signal is an impulse repsonse. I am filtering the signal using a windowed sinc filter in both frequency and time domain. I am interested in knowing the differences between the two methods and ...
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Bode plot phase shift equation when poles and zeros are not at the origin
Let $$H(s)=\frac{s^{n}}{s^{m}}$$
For $n \ne m$ the phase shift between output and input will be
$\frac{\pi}{2}(n-m)$.
For situations where the poles and zeros are not at the origin, I could find the ...
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Sampled data plot doesnt make sense
I've measured an accoustic signal for approx. 90 seconds with a sample frequency of 192 kHz (Note: the used device can sample data with maximaly 192 kHz, therefore i am not 100% certain, what sample ...
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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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Mixer and control systems
A mixer in the time domain usually multiplies 2 signals of the time domain , however what does it do in the Laplace domain?Is there a equivalent block diagram of a mixer in the Laplace domain?The ...
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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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Why is the convolution of two sine waves a sinc function?
Problem/Question
After taking the convolution of two discrete sine waves of the same frequency and length the result appears to be a sinc function but I was expecting to get a sine wave since this ...
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Freq domain filtering in a sample by sample basis
Im simulating a system in code, the real system uses a 3Mhz sample rate on PDM, trying to simulate the feedback response, in the feedback path there is a system, this system has a impulse response of ~...
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Frequency domain derivation of Hilbert transform of $\cos(\omega t)$
I'm reading "Understanding Digital Signal Processing, 3rd Edition" by Richard Lyons. Chapter 9 derives Hilbert transform impulse response by defining it in frequency domain first and then ...
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FMCW Radar - What's wrong with the transmitted signal model?
I am new to FMCW radar and trying to plot the transmit signal over time.
As you know, the transmitted signal is modelled as:
$$s(t) = cos(2\pi f_c t + \pi S^2),$$
where $S = BW/T_{chirp}$ is the slope,...
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Does subtracting a phase from the frequency components of a DFT output result in rotation?
I'm currently reading a paper (Page 23 of the PDF) about the application of the Fourier transform to standardize some climatic data to easily compare them.
I have the following text :
2.3 ...
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Routh's stability condition
Assume we have a LTI system which has poles in the half left plane of the s domain.
Before I learnt Routh's stability condition I had imagined that this was enough to decide whether a LTI system was ...
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Can we do down sampling by taking fft, omitting samples on the ends of the spectrum, and then taking inverse fft?
Suppose that we have a signal with a length of 4096 and want to down sample it by a factor of 2 and obtain a signal with a length of 2048.
Suppose that the the maximum frequency content of the signal ...
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What is the symbol for angular frequency?
I am reading the book
Signals and Systems Laboratory with Matlab Book by Alex Palamides and Anastasia Veloni
I was going through chapter 6 (Fourier transform) and I came across a confusing thing ...
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Signal Spectrum Anomaly and Interference Detection
I am trying to detect anomalies (interferences for example) given signal spectrum data in discrete form (frequency vs power spectral density) in python or matlab.
I am trying to do this in 2 scenarios....
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345
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Removing zero frequency peak in fourier spectrum
I have been looking at the FFT (in python) of various simple functions. Everything was working as expected, except when I take the Fourier transform of the function:
$$ f(t) = e^{-\gamma t}\cos^2\...
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How to Solve a Composition of Convolutions from Regularized Least Squares Model in Frequency Domain
Assume we need to solve the model:
$$ \arg \min_{\boldsymbol{x}} \frac{1}{2} {\left\| \boldsymbol{h} \ast \boldsymbol{x} - \boldsymbol{y} \right\|}_{2}^{2} + \frac{\lambda}{2} {\left\| \boldsymbol{g} \...
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What should be the size of my FFT values for speed,acceleration,..?
I am not from electrical eng. or physics background, so a layman explanation would be appreciated. I work with sensor data (accelerometer) from wearable device, collected for few hours.
I take few ...
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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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201
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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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459
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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 $\text{...
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Multiplication in frequency domain for a signal containing a whole frequency spectrum
Imagine we have two signals in the frequncy domain X(f) and H(f), for one of the signal H(f) I have the complex pair and the frequncy at which that complex pair exists. The second could be any random ...
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Does LPF limit the maximum sampling frequency of the input signal? [closed]
Consider the system where the signal passes through analog LPF with cutoff frequency of 50 Hz, so the maximum sampling frequency of the input signal could be 100 Hz (according to the theorem). But can ...
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529
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Phase extraction from Fourier transform
Is it possible in principle to correctly extract the phase from Fourier transform?
I just tried to do so using Python, here some attempts:
...
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711
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Bandwidth visualization in frequency domain
Consider some signal in frequency domain:
the maximum length of which corresponds to the half of the original signal ($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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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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