# Questions tagged [frequency-domain]

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### 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?
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### 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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### How to convert filter into frequency domain to do filtering?

I have this filter: filter_2 = firceqrip(2,0.6,[0.05 0.03]); I want to convert it to the frequency domain to multiply it by a signal (i.e filter in the frequency ...
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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 ...
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### 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 ...
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### 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 ...
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### 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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### 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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### 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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### 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 (...
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### 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? ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### Convolution of BPSK signal in frequency domain implementation

Here is the simplified version of code which implement convolution of BPSK-signal in frequency domain: ...
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### Does each pixel of the original image has a corresponding coefficient for every scale and every direction calculated by the DWT?

I want to take a pixel and find its coefficients calculated by the discrete wavelet transform for every scale and every direction. But as the DWT subsamples images, I don't see how to do that. Do I ...
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### frequency domain zero padding in OFDM

I have a matlab code for OFDM system, in this code the auther added a zero padded subcarriers before the IFFT stage, in the middle of the raws, and added zero padded guard interval after IFFT, my ...
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### Corresponding frequency domain filter of spatial domain filter in image processing?

My question is: Suppose that we have low pass spatial domain filter that averages 4-connected neighbors of that pixel and it doesn't consider its pixel in averaging. Find its corresponding filter in ...
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### Why does changing the frequency of a single component change total sum of amplitudes in my FFT?

I have the following code which generates a single simple sine wave with amplitude $1$ and then calculates the Fourier transform, normalises it, and finally takes the sum of all the components. ...
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### Relationship between $y(t)$ and $Y(f)$ in LTI system

If I'm given an LTI system. And I'm supposed to find the input $x(t)$, given $y(t)$ and $h(t)$. Am I able to use this relationship: $$X(F) = \frac{Y(f)}{H(f)}$$ Another question I have is if I'm ...
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### Phase wrapping in Bode plot

I'm trying to model the transfer function of a linear system (a MOEMS mirror) based on a datasheet plot of its response. I'm developing the model in the python-control model and I think that I've got ...
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### How to determine the central frequency from a vectorial spectrum analyzer?

I have taken measures of an antenna with a vectorial spectrum analyzer. I need to obtain the central frequency at which the antenna works. In order to do so, I have selected S11 (reflection) and I ...
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### iZotope RX's FFT processing?

How does iZotope RX handle the FFT (i.e. how does it manage to perform those processes in the frequency domain without creating glitches) since its able to e.g. Apply another DSP process (even time-...