Questions tagged [frequency-domain]

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234 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 (...
286 views

How to effectively teach topic of frequency domain?

This is a soft question. The frequency domain has made revolution in the field of Mathematics, Digital Signal and Image Processing etc. Some of concepts which are very difficult to analyse in spatial ...
585 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 ...
62 views

Relation of zero-padding and frequency resolution

Consider simple rectangular pulse and FFT of it in Python: ...
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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?
166 views

Is it true that each and every signal has multiple frequency components?

Usually when we observe spectrum of a signal,we see multiple frequency components, each having different contribution to amplitude But is it true that each and every signal has multiple frequency ...
3k views

How do I perform a time domain phase shift in the frequency domain?

I've seen some information on this topic around, but I don't quite understand it. I have a time domain signal. I understand that if I want to time shift this signal, I can do so by multiplying its ...
173 views

Fourier transform

Fourier transform of a DC signal is an impulse at the origin. Now if the spectrum of a signal is the plot of the amplitudes of the respective frequencies of each harmonic, then the Fourier transform ...
496 views

Smallest FFT buffer size given zero-padding

I am currently working on a project that involves processing an audio signal by dividing it into chunks of size B. The buffer is then zero padded to have a size of 44100 points, after which FFT is ...
351 views

1k views

sketching frequency domain representation

I've been given this signal and asked to sketch a frequency domain representation how do i do that? how do you know which frequency components are present in the signal?
2k views

Finding maxima and minima of a continuous time signal by using frequency method?

I have a PPG signal and I wanted to write a code that gives the maxima and minima value of signal by using frequency domain method. Any suggestions?
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What is doppler tolerance

Can anybody explain the meaning of Doppler tolerance for the waveforms(Linear frequency modulated, Barker code, Polyphase codes) used for Pulse compression. The Doppler frequency shift $f_{d}$ due to ...
60 views

Frequencies calculation of discrete signal in frequency domain

I have some misunderstanding in definition of frequency resolution of the signal. Here it is assumed that the resolution is: $$\hat{f_k}=f_{signal}\cdot T_{sampling}$$ (which is just relation of ...
37 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 ...
34 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 ...
340 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 ...
134 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 ...
56 views

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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Implementing a Band-Pass Filter from Scratch

I am trying to implement a band-pass filter from scratch. Here is an article which I thought explained the nuts and bolts of how to build one; the author combines a low-pass with a high-pass filter (...
772 views

What proportion of a padded FFT should be actual values

For a given signal, I've been told that you can pad the vector with $0$s at the end to get a larger DFT, and as a result get more precision in frequency bins. What are the limits to this approach? ...
2k views

Comparing PSD two signals of different length

I have two time signals A and B which are of different length, length(A) < length(B). Now I calculated the cumulative PSD of both signals. What is the best way to compare this result? If I am ...
845 views

filtering in frequency domain

I am performing decorrelation of two channels of audio using all pass filtering. The two all pass filters for two channels are of very high order (>1000 but with not all coefficients non zero). I have ...
53 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 ...
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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 ...
370 views

characterization of DC component

Consider the following two statements: In time axis: A signal without a DC component is a signal which doesn't have the zero frequency (the DC frequency) A signal without a DC component is averaged ...