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Questions tagged [spectrum]

The frequency domain of a wave-like function.

Spectrum refers to the full range of all frequencies of electromagnetic radiation. Spectrum has since been applied by analogy to topics outside of electromagnetic radiation. For a complete discussion, see the Wikipedia Spectrum article

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calculate a power spectrum with FFTW without calculating phase information

I want to use FFTW to calculate a power spectrum of a signal. Using the real transforms (in ) I can simply calculate the discrete fourier transforms for the sine- and cosine-functions, square the elements and add them together respectively.…
exocortex
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How to scale FFT output of wave file?

Wave file: 44100 Hz, 16 bit, dual channel. I use FFT to calculate magnitude at each frequency bins of output. But I don't know to scale it to draw (real-time) spectrum. Anybody can help me ?
cobazet
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How to subtract baseline from spectrum with rising tail in python?

I have a spectrum that I want to subtract a baseline from. The spectrum data are: 1.484043000000000001e+00 1.121043091000000004e+03 1.472555999999999976e+00 1.140899658000000045e+03 1.461239999999999872e+00 …
T Walker
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Getting FFT result peaks at 0 Hz

I have an audio frame which is a NumPy array of length 16000. When I apply numpy FFT to the audio frame, I get a spectrum that peaks at 0 Hz. I tried different audio frames from the same audio file but all of them seem to have peaks at 0 Hz. Could…
Akihero3
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How to get audio peaks with FFmpeg?

I am working on a music app and need to generate audio spectrum for my files. Like this one: So I tried using audiowaveform like this: audiowaveform -i music.mp3 --pixels-per-second 1 -o out.dat which gives me the following results[correct…
hmak.me
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Why is there a dB difference in the spectrum analysis between Sonic Visualizer and my Python script?

It seems I have an issue in the implementation of a function to create a frequency spectrum from an audio file. I ask this question in the hope someone will find the problem. You can download the 32bit float WAV audio file here. I am working on a…
Flovdis
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Python calculate the upper sideband spectrum of a pulse

I search for a numerical way to calculate the sideband spectrum of a time-varying signal V(t) using: I tried to obtain the upper sideband using the Hilbert transform first import numpy as np import matplotlib.pyplot as plt from scipy.signal…
beneminzl
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How to extract frequency and value of a recurring values in an array in Python?

I have an array consisting in payments on a bank account, sorted per day. I would like to extract recurring payments, such as salaries, for instance. An example is given in the linked data file. The monthly salary (e.g. 3139.75 in this example) is…
Bertrand Delvaux
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Pre-processing Audio Spectrum Data in Unity

I'm trying to pre-process a song and implement some beat detection before playing the song (not in real-time as the song plays). My basic idea is to sample the spectrum data at about 90 times per second and I'm trying to do that by incrementing…
Derek Leidemann
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SDL and Aquila FFT

I am working with wav file and want to apply fft to it. I am using Aquila C++ library and SDL2.0. I have already loaded wav file using "SDL_LoadWav" function of SDL. Now I have a vector buffer of type float. I want to apply FFT to it. I am not sure…
aak
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C# audio-fingerprintting in small wavs

I need to find in a similar wav file in a small database of around 40 files with lengths from 5 and 7 seconds. These wav files are the records that the telephone service provider gives your when you make a call. Example: https://clyp.it/lnz1aybd My…
Fraga
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convert RGB pixel to wavelength

I need to identify a spectrum emitted from a light source (spectrometer). To do that, I need to convert each pixel to a wavelength. To overcome the problem that the RGB values do not have a single value, I will use a prism so that I will get an…
Moti S
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Use "lines" command with a vector of objects in R

I'm using R to analyze IR-spectras. What I'm trying to do is to make a list or vector of objects, in this case Spectras, and plot them into the same "window". I used the command plot(Spectrum1,...) for the first Spectrum and the commands…
franzalibaba
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How to Fourier transform an Interferogramm to an IR Spectrum using R?

Hello people of the Internet, I have an Interferogramm (time domain) and want to to Fourier transform it into a IR Spectrum (frequency domain) to obtain the peaks of the functional groups in the molecule. FTIR (Fourier Transformation Infrared…
user3182395
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Frequency spectrum of signal in Matlab

Here is the code I use to plot a function in frequency domain in Matlab: dt = 1/10000; % sampling rate et = 0.1; % end of the interval t = 0:dt:et; % sampling range y = 2+sin(2.*pi.*50.*t)+18.*sin(2.*pi.*90.*t)+6.*sin(2.*pi.*180.*t);…
etf
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