Category: FFT & WAVELETS

Im simulating a system in code, the real system uses a 3Mhz sample rate on PDM, trying to simulate the feedback response, in the feedback path there is a system,…Read morefft – Freq domain filtering in a sample by sample basis

I am currently analyzing sensor signals in MATLAB. As you see FFT is done for the raw and filtered signal. This is just an exemplary filter, which I need to…Read morematlab – Recognizing relevant signal frequencies

I suppose, in human’s voice and in violin’s sound first harmonic’s fft abs is greater than half the maximum You are supposing wrong. The harmonic structure can be quite complicated…Read moreWhat’s the best snipet for get the first batch of matlab’s fft abs greater than half the maximum?

Can a FFT be recreated by performing STFT on the smaller time intervals and then summing them up. No. The STFT loses no information, it’s invertible. Until that is, you…Read moresignal – Mathematical difference between FFT and STFT

I am trying to play around with Fourier transform and there is something I do not understand. What I think I understand: So when you transform your images to the…Read moresignals – Custom Fourier frequency matrix gives wierd results

FFT Explorer will let you interactively produce 2 independent waves, sin, triangle, or square from 1 to 60 cycles as well as their phase from 0 to 2pi. The FFT…Read moreDownload FFT Explorer Free for Android – FFT Explorer APK Download

Outputs of FFT are complex numbers. The method complex forward calculates the FFT of the fftData and puts it back in fftData. The even indices are real parts of the…Read moreFrequency with fft.complexForward | Shouland

time = np.array(range(100))/100 wave = np.sin(2 * np.pi * 10 * time) + np.sin(2* np.pi* 70 * time) fft_wave = np.fft.fft(np.fft.fftshift(wave)) psd = (fft_wave * np.conj(fft_wave))/len(wave) freq = 1/(0.01 *…Read moreFrequency is wrong in numpy fft

I would like to convert time-domain wave elevation (sea waves) for irregular waves to the frequency domain to get Jonswap Spectrum. I got the time-domain response from open software by…Read morematlab – Conversion of time domain resposne to frequency domain

I need to compute the complex cross-correlation between two signals a and b and the take only the maximum value of the cross-correlation, regardless of the lag time where this…Read morefft – Cross-correlation in time or frequency domain (FPGA)

FFTW claims: “FFTW computes an unnormalized DFT” That is, for ifft they compute However, as stated on for instance wikipedia, the inverse DFT is defined as So the fftw output…Read moreFFTW producing different results from numpy.fft

Your FFT code doesn’t give you frequency. It gives you an array of complex values at a bunch of different frequencies. And there may be a bug in your code…Read moreGet sound frequency with Android FFT

So, decomposing a large DFT into smaller DFTs, where some computations are redudant, is exactly the trick the Cooley-Tukey algorithm uses. So, your FFT is already doing that internally, and…Read moreCan a FFT be decomposed into multiple parallel channels?