Questions tagged [frequency-domain]
The frequency-domain tag has no usage guidance.
205
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15 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
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1answer
28 views
Absolute value based AM envelope detection viewed in the frequency domain
In my understanding when a passband AM signal is demodulated with an envelope detector taking the absolute value restores the original baseband version of the signal and the low-pass filter removes ...
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1answer
35 views
GPS Receiver in Frequency Domain
I'm trying to transmit and receiver the GPS payload in both Time and Frequency Domain.
For transmitting and receiving in time domain :
...
0
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1answer
42 views
Spectrogram of an executable binary [closed]
One of the approaches I have been searching so far is the application of utilizing Neural Network to classify Spectrogram images, which is heavily used in speech recognition.
I am conducting an ...
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0answers
17 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? ...
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4answers
83 views
Remove brighter regions in an image on frequency domain
I'm newbie and maybe this is not the right place to ask this question, or this question has no sense.
I'm very interested in working on filtering images on frequency domain. I have found a few ...
2
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1answer
86 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 ...
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0answers
34 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
59 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 ...
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1answer
50 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
43 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 ...
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0answers
163 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
38 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 ...
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1answer
85 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
20 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
44 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 ...
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1answer
39 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 ...
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2answers
89 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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1answer
48 views
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15 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
81 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
822 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 ...
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0answers
39 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
44 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 ...
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0answers
36 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
19 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 ...
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2answers
294 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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22 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
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1answer
202 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
123 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
votes
1answer
60 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
votes
1answer
565 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
161 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
34 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 ...
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1answer
85 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
55 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
160 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 ...
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2answers
1k 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
61 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 ...
2
votes
1answer
203 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
52 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. ...
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1answer
94 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 ...
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2answers
619 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
vote
1answer
1k 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
4k 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
192 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
1k 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
votes
1answer
65 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
111 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
62 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 ...
