Questions tagged [frequency-domain]
The frequency-domain tag has no usage guidance.
197
questions
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1answer
67 views
get poles and zeros of frequency response
I am working on a python based LTSPICE project.
I would like to get poles and zeros of AC simulation data. Is there a way to get them under use of the magnitude and phase out of the frequency ...
0
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0answers
27 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 ...
3
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2answers
57 views
Idea for Noise Level Estimation / Automatic Thresholding in the Presence of Peaks
I have the fft of some signal, and want a rough estimate of the noise level in order to choose an appropriate threshold for our peak detection algorithm. In general, the fft contains mostly noise with ...
-1
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1answer
48 views
Sampling of frequency response
Let's consider any physical quantity depending on the frequency. For example, the impedance of a certain electrical component: $Z(f)$.
Now, imagine to measure it in a continuous interval of ...
0
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1answer
38 views
Filtering in the Frequency Domain - DIP [closed]
I am trying to do some filtering with a gray scale image in the frequency domain. I am just getting into matlab after some time away from any signal processing or coding and can't quite seem to get my ...
0
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0answers
106 views
Do negative frequencies count towards null-to-null bandwidth?
I am aware that negative frequencies do not normally count towards the bandwidth when transmitting in the baseband. However when specifically asked to look at the null-to-null or zero-crossing ...
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0answers
32 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 ...
-2
votes
1answer
81 views
How do I decide which frequencies are signal and which are noise?
I have an arbitrary recorded digial signal, on which I have run a Fourier transform. I'm not sure what conventions are on a case like this, but I have 1024 frequency bins. Second bin is the highest ...
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0answers
16 views
How to search for irregular signals: Fourier, DWT or k-means?
See my notebook here
I want to search for irregular time signals in a data set of ~3 500 000 time signals. By eyeballing I have found hundreds of flat and oscillating signals, but just a few that are ...
0
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1answer
40 views
What is Imaginary in Fourier transform?
How to plot graph of $e^{-t}$ in frequency domain. What would be the axis? If its Fourier transform is $1 /(1+j\omega)$, then how can we plot imaginary on frequency domain (amplitude vs frequency ...
0
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1answer
35 views
Contributions to a DFT frequency bin
So, a frequency bin is centered around an interesting frequency $f_0$. Assume the spectrum is such that there is no spectral leakage from other frequencies to that specific frequency $f_0$. Now. I ...
1
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2answers
66 views
Is the value of a frequency bin of a DFT-output the average of the 'real' frequency values within that bin's range?
I am wondering whether the value of a frequency bin with a certain resolution is the average of the fourier transform values of the 'real' frequencies within that bin's range.
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44 views
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14 views
Is the Channel Equalization corrects Carrier Frequency Offset (CFO) in signal?
As we know channel equalization is used for restoring the distortion ocured in signal. Hence, can we say the Carrier Frequency Offset (CFO) is being corrected and restored the actual signal.
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2answers
66 views
Can a 1-dimensional signal be in a domain other than the time or frequency domain?
In signal processing I have only heard of signals being in the "Time" domain or in the "Frequency" domain, but are there situations where a signal is not in either of these?
If so, what are these ...
2
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1answer
492 views
Extract frequency data from MP3 file
I want to do frequency analysis of audio data, basically trying to figure out what the notes are in a song algorithmically. The standard approach is to decode the MP3 into PCM data and run it through ...
0
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0answers
28 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
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1answer
43 views
What is the result of fourier transform of an image
I am new to computer vision and Fourier transform concept. I have examined some codes. In those codes, an image is performed Fast Fourier transform by using the function ...
0
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0answers
26 views
How to get PSD from frequency domain representation of time-series data [duplicate]
Let's say we have a realization (time-series data) of a random process. I take fft() of that to get its frequency domain representation. Then how can I estimate the PSD of this random process by ...
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0answers
16 views
How to match resolution of two or more signals
I have received the following 4 time-series signals and wanted to do some data analytics using these. Although the sampling is the same for all of these signals, 2 samples per second, problem is that ...
0
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2answers
208 views
Circular Convolution Matrix of $ {H}^{H} {H} $
We all know that Discrete Fourier Transform (DFT) corresponds to circular (not linear) convolution. That is to say, if $x(n),h(n)$ and $y(n)$ is the original signal, the filter and output signal in ...
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0answers
20 views
Analysis of linear acceleration and angular velocity, how to?
Excuse me If you don't feel that this question is good enough, but at the moment this is my level of entry knowledge.
Imagine that you have 200 recordings from the sensors, and information that you ...
2
votes
1answer
168 views
Purpose of multiplying fft output by Hann window?
I'm working with some acoustic propagation models at the moment.
A feature I've noticed in 2 of these models is that the output of the model is often multiplied by a Hann window in the frequency ...
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0answers
101 views
Encoder: Quantization in Frequency Domain
The article, "Let’s build an MP3-decoder!" describes quantization noise in the time domain:
[masking] This property is very useful: not only can the nearby
masked signals be removed; the audible ...
4
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1answer
56 views
Amplitude Estimating Using a Windowed DFT
Let's say we want to estimate the amplitude A of a mono-frequent signal using a windowed DFT. The frequency of the signal is unknown, and the frequency resolution of the DFT is limited, thus it cannot ...
2
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1answer
418 views
Normalized cross-correlation in frequency domain
I never worked with signal processing and never really used Fourier transforms before, still I am working on a project consisting on taking the output of an accelerometer to detect some movement ...
0
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1answer
107 views
Why is the size of results from FFT half the size of the input, while that is not the case in image processing?
When dealing with real data, Fourier Transform produces symmetric results and FFT algorithms discards half of it. An input with 1024 points will yield only 513 points in the output.
However, in image ...
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0answers
33 views
Frequency Domain - Meaning [duplicate]
I'm new in digital signal processing and having hard time understanding this. By Fourier Transform I mean Discrete Fourier Transform as it's the only one I'm learning.
As far as I know Fourier ...
0
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1answer
71 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 ...
1
vote
1answer
53 views
How do I warp a 1 dimensional signal in frequency domain?
I want to implement VTLN (Vocal Tract Length Normalization).
It is equivalent to warping the signal in the frequency domain according to the following graph.
I can't wrap my head around how one ...
1
vote
1answer
113 views
Visualising OFDM subcarriers in the frequency domain
Im struggling to understand why in some images the frequency domain shows clear bars with amplitude and phase and with 0 frequency variation (it is clear that the frequency of the waves does not ...
0
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2answers
799 views
Sampling with an alternating impulse train
The have the following question:
A signal $m(t)$ with bandwidth 500Hz is first multiplied by a signal
$g(t)$ where $\displaystyle g(t)=\sum_{k=-\infty}^{\infty}(-1)^k \delta(t-0.5*10^{-4}k)$. The ...
0
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2answers
55 views
How to interpret correlation angle from frequency domain
Since the coefficient of one frequency could be seen the length of the signal projects on that frequency basis.
And the length is
$$|a|\cos\theta= \frac{a\cdot b}{|b|} $$
If I divide the ...
1
vote
1answer
171 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 ...
0
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1answer
51 views
Counting blinks of a LED
I'm working on an algorithm that counts blinks of a LED. I have series of non-neagtive integers. They represent brightness of a LED in time. I give you two examples of these integer series below. ...
1
vote
1answer
78 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 ...
0
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2answers
498 views
Why do frequencies of analog signals range from $-\infty$ to $\infty$ while frequencies of digital signals are restricted to $[0,2\pi]$?
In Fourier analysis while dealing with discrete-time signals, frequencies range from $0$ to $2\pi$ why? Intuitively how can i understand it?
1
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1answer
978 views
Computation of the Inverse DCT (IDCT) Using DCT Or IFFT
Is there a way to compute the inverse discrete cosine transform (type-2) by leveraging either a DCT, FFT, or IFFT algorithm? I have seen ways to compute the DCT using FFTs, and I've seen ways to ...
0
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2answers
3k views
Understanding the frequency domain [duplicate]
I'm trying to understand what frequency domain is. I found general explanations on the Internet, for example:
frequency-domain graph shows how much of the signal lies within each given frequency band ...
2
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1answer
184 views
Convolution Offset and Factor in Frequency Domain
See this link. The following Convolution in Spatial domain code is written in C#.
...
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2answers
956 views
Finite and Infinite support in time and frequency domain
It's known that signals with a finite support in time has an infinite support in frequency (talking about Fourier Transforms).
A common example that is given for the claim is the triangle function ...
0
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1answer
59 views
why transmitting a long pulse its spectrum gets spread?
I'm transmitting an RF signal with a CC1101 at 440 MHz.
This signal is a constant of 1, so the spectrum should be a delta.
Using a SDR dongle, I've checked the spectrum and it's wider than a delta ...
0
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1answer
87 views
Bilateral Laplace transform and existence of Fourier transform
I was reading from Athanosios Papoulis' "The Fourier integral and its applications." and they referenced the bilateral Laplace transform and Fourier Transform as:
$$F(p)=\int_{-\infty}^{\infty}e^{-pt}...
0
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1answer
60 views
Complex FFT reversing
I've succeeded to compute complex FFT of a data array of interleaved values using the arm_cfft_f32() API of the CMSIS DSP library for Cortex-M4, and got in the same array the FFT results as frequency ...
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0answers
16 views
Is there a criterion that says at what point you can distinguish 2 partially overlapping Lorentzian peaks?
If you have 2 Lorentzian peaks that partially overlap and you have some frequency resolution df (your points in frequency space are separated by df) and both Lorentzian peaks have FWHM $\Gamma$ is ...
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4answers
2k views
Why does the frequency in the DFT have to be an integer?
I don't know why the result of DFT and FFT in MATLAB like below images..
fs=128;
t=0:1/fs:1-1/fs;
x=cos(2*pi*3.5*t);
X=fft(x);
N=length(x);
n=0:N-1;
f=fs*n/N;
plot(f,abs(X)/N);
If I set the ...
0
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0answers
68 views
Plot Background Noise
I am a total newbie in signal processing.
I have been trying to plot on simulink a time/frequency domain noise in PLC (Powerline Communication) that matches a real-world research "...
2
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1answer
465 views
How to calculate a delay between two signals in frequency domain?
Calculation of a delay between two signals is generally done by finding the maximum in the cross-correlation of the two signals (in time domain):
$$
\tau_{delay} = \arg\max_\limits{t}(f(t) \star g(t))
...
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0answers
16 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 ...
4
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2answers
84 views
Why are LTI filters not able to output frequencies not present at the input?
I know this a very basic question but I'm just having troubles understanding why.
Thanks in advance!
