Questions tagged [frequency-domain]
The frequency-domain tag has no usage guidance.
48
questions with no upvoted or accepted answers
2
votes
1answer
295 views
Is it right to talk about dynamic range on frequency domain?
I'm comparing three frequency response's plots from simulations and experiments and I observed that two of them look like clamped to a DC component, where the max dB value is i.e. 100 and the min is ...
2
votes
0answers
176 views
$\tt ifft()$ function - absolute vs real form
I have multiple files from an experiment in frequency-domain that I would like to use ifft() function to convert to the time domain in R to apply signal processing ...
1
vote
0answers
56 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 ...
1
vote
0answers
37 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 ...
1
vote
1answer
92 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 ...
1
vote
1answer
162 views
Break a signal into segments, add them together and then perform an FFT on the result
If you break a 4 second signal into 0.5 second segments, add them together and then perform an FFT on the resultant 0.5 second data.
Will the FFT / frequency spectrum be the simlar to an FFT on the ...
1
vote
0answers
520 views
How to convert a spatial frequency in a 2D-DFT into the units radians per pixel?
Let's say I have a 2D image, and I take the discrete Fourier Transform (via FFT) of that image. In the frequency domain, I get the following image:
In this image, let's just assume all the spatial ...
1
vote
0answers
224 views
How do I find amplitude modulation effects in natural signals
It is relatively easy to discover overlaid (additive) signals in natural phenomena using wavelet decomposition, Fourier Transforms, CEEMD, etc, because addition in the time domain is the same as ...
1
vote
1answer
1k views
Envelope detection in frequency domain with MATLAB
I need to compute the envelope of a spectrum in MATLAB. Is there a specific function that can do it? I saw the function
[yupper,ylower] = envelope(x,np,'peak')
...
1
vote
0answers
81 views
Comparing the spatial frequency between groups of images
I have 2 groups of images, and I want to compare these groups based on the spatial frequencies of the images.
In the end, I'd like to be able to say "group A is/is not significantly different from ...
1
vote
0answers
133 views
Creating synthetic frequency domain box filter vs 4 pixels in corners
Creating two 10x10 black images.
1st image, adding a 2x2 white box in the middle (Low pass filter).
2nd image, adding 1 pixel in each of the corners.
Then performing the following steps in that order:...
1
vote
0answers
329 views
Why does my overlap-add integrator in frequency domain result in distorted signals?
With help from the dsp guide and DSP-Related, I tried to implement a leaky integrator in octave/matlab. It seems to work in general, but there are a few problems.
So that's what I do:
Calculate the ...
1
vote
0answers
105 views
question about the frequency of Gabor filters
The Fourier transform of 2D Gabor filters is shown below:
F is the radial frequency of the Gabor functions.
Another parameter Fm is denoted as highest central frequency.
Fr is the constant frequency ...
1
vote
0answers
791 views
Adding shot noise in frequency domain
I have a current signal represented by an array in python, which I would like to add shot noise to. Shot noise is defined as
$$
σ_i = \sqrt{2qI \Delta f}
$$
where $q$ is the elementary charge, $I$ ...
1
vote
0answers
110 views
How to optimize a wavelet transform?
I am using complex morlet wavelet to estimate frequencies and damping ratios in a 1-D signal. I have done it so far, and the results are accurate enough. Now my question is how can I modify or ...
1
vote
0answers
866 views
adaptive filter does not converge for all inputs
I am trying to make a frequency domain adaptive filter in matlab. It uses matlab adaptfilt.fdaf to create the filter parameters like step size and initializing initial filter weight values. Then I ...
1
vote
0answers
89 views
Keep the exact frequency content - Multidimensional fft
In Matlab I've got to generate a Gaussian process embodying a certain frequency content. Not to go multidimensional, I have used reshape function. I explain better ...
0
votes
1answer
23 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 ...
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
0answers
35 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
42 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 ...
0
votes
0answers
43 views
Is it possible to apply a fractional delay to even-length signals using the frequency-domain phase shift method?
Suppose I have the following Python function to apply any real-valued circular delay to a signal by multiplying by a phase factor in the frequency domain:
...
0
votes
0answers
25 views
In audio analysis, is the first rahmonic from the cepstrum equivalent to the first partial of a pitched sound?
I was reading this text from Oppenheim and Schafer, briefly explaining the concept of the cepstrum. I'm new to this concept.
He explains that the cepstrum is useful to quantize the distance between '...
0
votes
0answers
23 views
Does it make sense to apply convolution in the frequency dimension of a fourier transformed signal?
What I have is more likely a theoretical question. Since I am not from a signal processing background it is hard for me to grasp the issue in using convolution in the frequency dimension of a Fourier ...
0
votes
1answer
90 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
69 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
2answers
143 views
Smoothing in frequency domain and impulse reponse of the filter in time-domain
I have a low-pass signal in frequency domain, $$\left[f_{min}=0, f_{max}=20\,\mathrm{GHz}\right]_{n=100}$$
After re-configuring the input signal as
$$X=\left[-f_{max},\ \dots\ -f_{min},\ \mathrm{DC},...
0
votes
0answers
153 views
Frequency and Order maps
I'm new to python and I'm using it to analyse accelerations from an accelerometer ie. vibration analysis. For that I need to plot 2 types of diagrams:
1) Frequency map; frequency and time on the axis ...
0
votes
0answers
52 views
Time Frequency bin
I am doing research in audio signal processing for DOA estimation. I came across the term Time-Frequency bin. I have gone through several articles but none of them specify a TF bin rather it specifies ...
0
votes
0answers
19 views
Where can I find more information about how to create filters on frequency domain?
I'm newbie and I'm very interested in filtering images on frequency domain.
I haven't found a lot filters on frequency domain and I wondering how can I create new ones.
How can I create new ones? ...
0
votes
0answers
59 views
Range Migration Algorithm in FMCW MIMO RADAR
I’m using a FMCW MIMO radar [77-79 GHz] with a virtual linear array made of 48 channels.
I’m wondering if the adaptation of the range migration algorithm (typically used in SAR processing) is ...
0
votes
0answers
57 views
Find repeating sequences in audio file
I have a long audio file (12+ hours). I know that there are some unknown small (2 minutes each or thereabout, it varies) repeating (not bit by bit: it is recorded with a mic) chunks in it, repeating ...
0
votes
1answer
64 views
0
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0answers
101 views
Generating a phase modulation frequency spectrum with jitter
I would like to produce a frequency spectrum plot like this:
(from All About Circuits)
I know that one can take the modulation frequency and multiply it by a given order and scale by the modulation ...
0
votes
1answer
121 views
LP to BP transformation steps
Considering the following problem, What i know to convert from LP signal to BP signal is to:
Draw the FD of the LP equation
From it I can draw the FD for BP
From this graph I can deduce the equation ...
0
votes
0answers
24 views
Is there a criterion that says at what point you can distinguish 2 partially overlapping Lorentzian peaks?
If you have 2 Lorentzian peaks that partially overlap and you have some frequency resolution df (your points in frequency space are separated by df) and both Lorentzian peaks have FWHM $\Gamma$ is ...
0
votes
0answers
75 views
Plot Background Noise
I am a total newbie in signal processing.
I have been trying to plot on simulink a time/frequency domain noise in PLC (Powerline Communication) that matches a real-world research "...
0
votes
0answers
17 views
What is the best spline to interpolate freq analiser graph
the question is as it is in the topic: What is the best spline to interpolate freq analiser graph?
I am looking something simply and fast to implement. I read about catmull-rom it looks it could be ...
0
votes
1answer
832 views
When listening in to an AM signals of various frequencies, how do we exactly tune in?
Alright, so I read on AM and Double Sideband AM, but I don't the more fundamental idea - the frequencies.
Frequency is just: $ \frac{1}{T} $, where T is period
So difference between 5 Hz and 30 Hz ...
0
votes
0answers
4k views
Operations applied to functions in time domain and frequency domain
I am trying to make a succinct summary of how algebraic operations in the time domain translate in the frequency domain (via the use of Fourrier/Laplace transforms). Here is what I have derived so far:...
0
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0answers
69 views
Frequency Domain Equalization [Sources request]
When I read papers, I often see the term "Frequency Domain Equalizer".
I do not understand what a "frequency domain equalizer" is.
Do they mean equalizers like MMSE, LMMSE?
Or is there an equalizer ...
0
votes
0answers
197 views
Poles and zeros from FRF
How can I determine the poles and zeros of a system given its frequency Response?
I can understand how one can find the Frequency response from poles and zeros of a system. Is it possible to do it ...
0
votes
0answers
259 views
Determining Valid DTFT's
Are the following frequency domain signals valid DTFT's (Discrete Time Fourier Transforms)? Answer yes or no, and justify your answer.
a) $X(\omega) = \omega + \pi$
b) $X(\omega) = i + \pi$
c) $X(\...
0
votes
0answers
414 views
FFT frequency domain averaging and zero padding
I'm trying to get the average frequency response of an entire piece of audio by splitting it into segments, doing an FFT on each one, and averaging the magnitudes together. Its working great until I ...
0
votes
0answers
469 views
FFT of irregular shaped data
I have an irregular shaped 3D image that I want to do frequency domain filtering on. Currently I simply zero-pad the data to make it a cube, then do an fft.
I was wondering if this was a valid ...
-1
votes
1answer
378 views
Alignment of signals for ensemble averaging? Something else?
I have been applying ensemble averaging (adding signals of different trials to obtain one signal) to improve Signal to noise ratio in my data. I have achieved good results in terms of classification ...
-1
votes
1answer
386 views
fft2 of interferometric image - how to interpret the result in term of dominant frequency
I have an interferometric image which shows fringes at a certain frequency, basically a dominantly periodic signal overlaying the information that I want to extracthere are the fringes that I want to ...
-2
votes
1answer
1k views
