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Questions tagged [ifft]

NOTE: please use the FFT tag instead. The FFT is a type of algorithm for quickly computing the Inverse Discrete Fourier Transform.

The IFFT is an FFT algorithm with some different initial permutation of data samples, and often an additional normalization, such that the algorithm computes the IDFT rather than the DFT. The FFT and IFFT are always implemented by the same code.

Related topics include , , , .

More information on the IFFT can be found in the Wikipedia article on the FFT

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fft / ifft deconvolution in Matlab

I have a time varying signal (time,amplitude) and a measured frequency sensitivity (frequency,amplitude conversion factor (Mf)). I know that if I use the center frequency of my time signal to select the amplitude conversion factor (e.g. 0.0312) for…
2one
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MATLAB: Using ifft() to deconvolve signal and frequency response

I have a measured time varying signal which is known to have a variable frequency response (I have freq vs. sensitivity data for the measurement device). I want to deconvolve using: pt = ifft(fft(vt)./Mf) where vt is the time varying signal and Mf…
2one
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MATLAB: Using ifft to extract original signal

I have a time varying signal (with a fundamental frequency and a number of harmonics) which I have computed the fft() of and then divide this by a frequency dependent sensitivity, M(f). I then want to convert back to the time domain using ifft() to…
2one
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python fft plot "type error"

I am getting following error when I am plotting the FFT of signal. The code reads the signal samples from the .txt file. TypeError: Cannot cast array data from dtype('S17') to dtype('complex128') according to the rule 'safe' #%% Import…
Sachin Anchan
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Matlab IFFT in 3-dimension

I am trying to use Matlab's ifftn in 3-dimensions to get solution in physical space. In particular I am trying to use ifftn on 1/k^2. The analytical solution to that in physical space is 1/(4*pi*r). However I am not recovering that. Please note: $r…
Brato
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Matlab FFT2 normalization after processing

I am trying to understand how the MATLAB FFT normalization works. Lets discuss the following example. %% sum2D = @(a) sum(reshape(a,1,[])); % sum elements in 2D matrix a = [0 0 0; 1 2 1; 1 1 1; 1 1 1; 0 0 0] f1 = fft2(a) m = [0 32 0;…
bordart
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Using interpolation of a signal to change the frequency

Using interpolation of a signal to change the frequency. If the original signal / sample length = 200 I know if I double sample length I get 400 and interpolate the new sample length (400) to the old sample length (200) I will get twice the…
Rick T
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frequency to time conversion using MATLAB

I would like to convert my data in frequency domain into time domain. In this attached excel sheet (book1.xlxs) Column A is Frequency. Column B and C is real and imaginary data (B+jC). Also attached you can see my code. But its not working. I would…
user3797326
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Transform from frequency domain to time domain (IFFT)

I have a FRF and I want to transform it from frequency domain to time domain. here is my code, which I doubt if it`s correct or not. FRF_Z_Zb = FRF_X0_Zb(1,:); %% IFFT %% FRF_Y_Zb = FRF_Z_Zb; FRF_Z_Zb_flip = fliplr(FRF_Z_Zb); FRF_T = [FRF_Z_Zb…
Mehrdad Bakhshi
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Simulink implementation of Fourier Transform Property of Integration and Differentiation (Part 2)

So this is a continuation of the thread in this link: https://stackoverflow.com/questions/33677430/simulink-implementation-of-fourier-transform-property-of-integration-and-differe# I've made some progress (I think) and I now have this: The output…
John
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Inverse discrete Fourier transform of across specified dimension in Python/Numpy

In Matlab, ifft(X,[],2) (link to documentation) computes the inverse discrete Fourier transform of X across the dimension 2. Is there a way to accomplish this with numpy.fft.ifft (link to documentation)?
bfletch
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Taking IFFT2 of data set and what is means

I am dealing with a data set collected from a bistatic radar system which has electric field amplitude vs frequency points. I am trying to take the inverse fourier transform of the data set, converting from the frequency domain into the time…
cecchollett
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Difficulty plotting correct IFFT of 2D function from given data

I am trying to read in a 2D data set into a matrix, plot the matrix, as well as plot the IFFT of the matrix. The data is 128x2 data set, with frequency in the first column (A) vs amplitude in the second column (B) Unfortunately, plotting the matrix…
cecchollett
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Difference between summation of motion components and IFFT?

I want to use IFFT to obtain the time signal from freqency data, being response amplitude operators (RAO's) and phase shifts of a vessel over frequency range 0.1-2.6 RAd/s, having 200 samples. I first used a very unrefined method to obtain the time…
Moon
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Inverse Filter for Gaussian Blur

I recently used a Gaussian convolution to blur an image. It works well, in fact it works excellently. However, now I'm trying to reverse it and my inverse filter keeps running into problems. The filter is supposed to run on the following…
Woody1193
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