Questions tagged [frequency-domain]
The frequency-domain tag has no usage guidance.
258
questions
0
votes
1answer
27 views
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 ...
0
votes
0answers
49 views
Frequency offset estimation accuracy
To improve frequency offset estimation, we could:
Use the second order interpolation / equation in the frequency domain based on the coarse estimation fc, e.g. BPSK frequency offset estimation;
Zero ...
4
votes
2answers
113 views
Explain the Process of Spectral Pooling and Spectral Activation in the Context of CNN in Frequency Domain
I am reading the paper Design of an energy efficient accelerator for training of convolutional neural networks using frequency Domain Computation:
which uses Frequency Pooling, from Spectral ...
0
votes
0answers
39 views
Why is the mel filter bank used to create a mel spectrogram?
The formula for converting frequencies from Hz to mel scale is as follows:
$$2595\log(1+f/700).$$
So why is the mel filter bank used? What is the origin of the mel filter bank?
0
votes
1answer
19 views
Going from an MFCC coefficient to Hz range?
I have not worked with MFCCs before, but I am faced with the observation that the 5th MFCC of a signal is actually of interest for me in my speech research. In order to understand why that one is ...
0
votes
2answers
47 views
unsymmetric fft in matlab
This is the FFT of a 4khz sin signal. I wonder why the negative part and positive part of X axis is not symmetrical?
...
4
votes
2answers
68 views
Constructing frequency domain filter from a 2d spatial kernel
Given a 2d spatial kernel $h$, I want to construct the corresponding frequency filter $H$. In theory, $H$ is simply obtained by calculating the DFT of $h$ using a FFT algorithm. But in practice, there ...
0
votes
1answer
42 views
Spectrum in real life with Spectrum in theory
as you know it is possible to measure the power spectral density ($|X(f)|^2$) of a certain voltage signal $x(t)$ through a Spectrum Analyzer.
As far as I'm concerned, the simplest spectrum analyzer ...
1
vote
1answer
232 views
Why is modern control theory in the time domain instead of the S-domain?
I am not sure if I am missing something, but from what I read I understand that modern control systems work in the time domain rather than the frequency frequency or S-domain.
Wikipedia article ...
0
votes
2answers
39 views
Power Spectral Density as a single number confusion
I'm trying to recreate the results of a machine learning applied to the DSP classification in the article: link.
I have a signal (activity measurements from a smartwatch) per patient, so about 30 ...
0
votes
1answer
37 views
Frequency domain filtering: must filter coefficients always be conjugate symetric?
While trying to do frequency domain filtering of audio signals using windowed overlap-add methodology, I came across some pre-calculated frequency domain coefficients. I noticed that the coefficients, ...
0
votes
1answer
68 views
What does frequency weighting an acceleration signal mean? And How do I frequency weight the raw acceleration data collected?
Disclaimer: I have very little knowledge in signal processing.
I'm trying to calculate a Whole Body Vibration(WBV) measure called Vibration Dose value(VDV).
$$VDV = \left(\int_{0}^{T}a(t)^4\,dt\right)^...
1
vote
1answer
42 views
Train of impulses in frequency domain
Why compressing a train of impulses in time domain produce a wide-spaced train of impulses in frequency domain and vice versa? i want to know the intuition behind that.
3
votes
1answer
102 views
Frequency-domain deconvolution: "Direct" filtering vs "Wiener" filtering
Can someone help with clarifying the difference between two approaches
to frequency domain "deconvolution:
For the frequency domain problem:
We want to find a filter $F(\omega)$ which will ...
1
vote
1answer
66 views
Measuring frequency response with white noise signal
I need to measure a frequency response of an eleсtric circuit (simple like an RC-filter). I suppose that I can generate an input signal that has spectrum like white noise (for example, m-sequence ...
0
votes
1answer
39 views
How to do sliding window multiplication in frequency domain
I want to perform the following computations with the impulse response of length L of a LTI system:
Multiply the impulse response with a window w(n) of length M << L.
Take the FFT of the result ...
4
votes
4answers
246 views
Estimation of Amplitude, Frequency and Phase of Linear Combination of Harmonic Signal Beyond the Leakage Resolution of DFT
How can I find a rough ( as accurate as possible) Amplitude of each frequency when there is spectral leakage.
Currently, I am dealing with a system that contains special leakage which seems ...
0
votes
7answers
181 views
Where do harmonics come from?
At first, I thought harmonics come from the signal being periodic. However, we know a sine wave is also periodic but contains a single frequency and no harmonics.
A harmonic for me is a component (...
1
vote
1answer
80 views
Estimating the SNR of 2-FSK
I have some iq data recordings of a 2-FSK waveform that I've created periodograms from. How do you estimate the SNR of this waveform in the frequency domain? I've heard two opinions:
One:
Integrate ...
0
votes
1answer
32 views
Amplitude in frequency domain of the same signal measured at different bandwidth (f_max - f_min) and different FFT lines
Fourier series in complex form
Fourier series in trigonometry form
Here, I'm measuring the same signal (an impulse force - or at least as close as possible to an impulse, represented by a knocking ...
0
votes
0answers
18 views
What is the requirement to reconstruct a spatial domain signal if we sample in the frequency domain?
I've come across an interesting question with regarding to signal reconstruction.
The sampling theorem states that a signal in the time or spatial domain must be sampled at twice a rate twice the ...
0
votes
1answer
39 views
Meaning of the frequencies vector using fft
I'm so confused, and it would be nice if someone could clear my head, or at least direct me to suitable references.
Assume that I have two gaussian pulses with the same bandwidth in time, but for 2 ...
1
vote
0answers
19 views
The best method to convert piano sound to music notes in real time [duplicate]
I was looking for a way to convert piano sounds to piano notes for my research. I discovered the conversion of piano sound to piano notes using FFT and piano note recognition using CQT. I am also a ...
0
votes
1answer
36 views
I need help interpreting FFT diagram
I need help with analyzing the computed FFT of my signal. I don't wanna bother by going into the details of how my signal is formed so I will just state which frequencies I know my signal has. I know ...
3
votes
1answer
381 views
The Proper Way to Do Sinc Downsampling (DFT Downsampling) 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 downsample it in the frequency domain (Sinc interpolation)?
4
votes
1answer
75 views
Finding the Transfer Function of a Multiplicative Distortion in MATLAB
I have the frequency response of two signals shown above. One is uncontaminated, and the other is the same signal contaminated by a multiplicative distortion with two poles and two zeros. I need to ...
2
votes
1answer
91 views
Dealing with bias in an FFT for frequency correction
I'm working on using an FFT for frequency correction of a generic modulation signal. My algorithm basically attempts to balance the energy in the positive and negative frequencies of the FFT to be ...
0
votes
0answers
37 views
Extrapolation of band-limited frequency data
I'm now studying "How to do accurate transform from band-limited frequency data specifically S-parameter data of high speed interconnect to the causal impulse response in time domain. There are ...
0
votes
0answers
55 views
Average of magnitude data
I'm trying to reduce my magnitude spectra, which I need in octave bands. I have 5 measurements of a sound source, recorded with the same microphone at different times. I want to get an average model ...
2
votes
1answer
120 views
Designing a Chirp in the Frequency Domain
I am trying to create a chirp signal in the frequency domain, by simply setting the magnitudes of each frequency bin to one, and then setting the phase delay function such that the resulting time ...
1
vote
1answer
49 views
The cost function of LS algorithm
I'm trying to understand the derivation of LS algorithm for channel estimation in OFDM.
Could anyone explain why do we need complex conj transpose in the below equation?
1
vote
0answers
89 views
Sweep synthesis in frequency domain: How to correctly adjust magnitude?
I'm attempting to synthesize a logarithmic sweep signal to measure the IR of a system. For the most part, I'm following Section 5.2 of the paper Transfer Function Measurement with Sweeps.
To generate ...
0
votes
1answer
44 views
Continuously changing pitch of stable-pitch audio sample
I have an 44100-rate 4 second sample of a legato violin playing at 440 Hz. I would like to modulate this sample so that it starts at 440 Hz, then transforms its frequency continuously and ...
1
vote
3answers
457 views
If a square wave is a sum of odd harmonic impulses, why is it continuous in the frequency domain?
A square wave is a sum of sinusoids so surely it should be represented as individual discrete impulses in the frequency domain, where all other frequencies are 0. Why instead are those intermediate ...
1
vote
0answers
38 views
How to downsample a fourier transformed signal?
I have a signal of length 100000 timestamps sampled at a frequency of 25kHz. First I apply a high pass filtering at (300Hz) and then do the Fast Fourier Transformation. Then the absolute values are ...
0
votes
1answer
33 views
Names of system functions in frequency domain
I was just trying to refresh my systems theory known from long ago, and I realized that I had forgetten the name of the basic functions. Specifically, what are the names of these functions ...
-1
votes
1answer
69 views
Is pitch detection for bass instruments a solved theme?
I would like to know if pitch detection is a solved theme for an instrument like a bass (bass tones).
Is it, or there is always a percentage of error rate on the detection?
0
votes
1answer
89 views
Why use PSD to analyze a signal instead of its Fourier Transform?
Let's imagine I have a perfectly known signal $s(t)$ and I want to analyze its frequency components.
I noticed that mostly everyone would use the PSD of $s(t)$ to do that, instead of simply use the ...
1
vote
1answer
66 views
Steady state variance of a stochastic differential equation - relation between the frequency and time domains
Consider a stochastic differential equation:
$$
dx(t) = a x(t)dt + b y(t)dt \quad (1)
$$
where $y(t)$ is a stochastic process satisfying $\langle y(t)y(t')\rangle = \delta(t-t')$. We will assume that ...
-2
votes
1answer
23 views
Is it possible to prove that dither VS PWM can result the same output?
Assume that we have a SISO transfer function model $G(s)$ and we want to look how the output looks like when we have a input signal $u(t)$ that looks like this:
$$u_1(t) = \left\{\begin{matrix}
50 + ...
2
votes
2answers
320 views
Proof of fourier transformation of multiplication of two signals
I've been trying to find a proof of the following, but still I m unable to proof it, can someone help me?
$$
ℱ[x(t)g(t)] = \frac{1}{2\pi}
[X(\omega)*G(\omega)]
$$
-1
votes
1answer
62 views
Time domain analysis vs frequency domain analysis? Applications wise? [closed]
When do we use time domain analysis and when do we use frequency domain analysis?
As far i studied i know that when we need to study individual sinusoidal components of a signal, we choose frequency ...
0
votes
3answers
421 views
What is the Effect of Multiplying a Function by the Unit Impulse Function in the Frequency Domain?
I know about the the shifting property of the impulse function in the time domain as can be seen in equation $(1)$.
$$
\int_{-\infty}^{\infty} f(x)\delta(x - a)dx = f(a)\tag{1}
$$
But what is the ...
0
votes
1answer
128 views
phase offset extraction using matched filter
I'm looking for an application of detecting the drift of a received signal carrier frequency from ADC clock of the receiver (in case of no drift, ADC clock should be optimally an integer multiple of ...
0
votes
1answer
80 views
ouput of low pass filter
$$y[n]=(-1)^n w[n]+w[n]$$
$n$ ranges from $-\infty$ to $\infty$
where $w[n]$ is output of frequency response block with cutoff frequency = $\pi/2$, and input is unit impulse function.
I know ...
0
votes
1answer
91 views
Derivation of Circular Mean Square Error
I would like to understand how Eq. (36) in [2] was derived:
The rationale behind the definition of circular sample mean in Eq. (37) is clear, but there is no motiviation for the CMSE definition in Eq....
1
vote
2answers
69 views
Digital filtering based on frequency component amplitude... why not?
I've got a very general question.
I've just implemented a filter working in frequency domain that simply cuts every frequency component whose modulus amplitude falls below a certain threshold value. ...
1
vote
1answer
36 views
Continuous frequency grid to discrete grid
I am designing a controller for a system using several methods, one of which is a discrete method. In the continuous time I am looking at a logarithmically spaced frequency grid in the range $$\omega \...
1
vote
1answer
145 views
Why does this transfer function estimation not work? System identification
Goal:
I have an unknow dynmical system $G(s)$ and I want to find it from measurement data, output $y(t)$ and input $u(t)$. The data is frequency responses.
Method:
I begun first with creating the ...
4
votes
1answer
452 views
Convolution Theorem using DCT
I am trying to digest this paper.
[2002] Anna Usakova. Using Of Discrete Orthogonal Transforms For Convolution
So far, I've been successful with DFT and DHT.
Could someone give a hand with DCT?
I am ...
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