Stack Overflow
Stack Overflow

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

389 questions
2
votes
2 answers

Generate next color in spectrum

everyone. How would I generate the next color in the color spectrum? Like, a function that takes a red value, a green value, and a blue value for input and output. I could input solid red (RGB 255, 0, 0) and it would output an orangish-red. EDIT:…
Babkock
  • 47
  • 1
  • 5
2
votes
2 answers

How to plot spectrum or frequency vs amplitude of entire audio file using python?

I have some audio files, I want to plot the average spectrum of the audio files like "audacity" software using PYTHON (librosa library). I can see they are plotting average frequency vs amplitude plot of the entire audio. After that, I want to…
taserghar
  • 340
  • 3
  • 15
2
votes
1 answer

Spectrum, option showInput, show a input text not editable

I have implemented a Spectrum color Picker, it works perfectly, except for the showInput option which makes the text input not editable, it is not even selectable, it does not even focus on itself. If I select the color, however, the hexadecimal…
Christian Parselli
  • 21
  • 3
2
votes
1 answer

Spectrum computed with Matlab FFT does not give a consistent result for different lengths of sample (same number of points but Fs different)?

I would like to plot profile of rugosity (from AFM measurements) but there are still this that I misunderstand regarding the FFT (especially in Matlab documentation). I want to compare two measurements, a.k.a. two rugosity profiles. They were done…
LeChat
  • 466
  • 3
  • 18
2
votes
1 answer

Python + Scipy: How to set the time frame for a spectrogram?

I'm trying to calculate the spectrogram for an audio signal using scipy.signal.spectrogram. As a project specification it is needed that the time frames be spaced 20ms from each other, but I can't find a way to set it. The maximum value I was able…
Ramon Balthazar
  • 3,907
  • 3
  • 25
  • 34
2
votes
4 answers

Find the most colourful image in a collection of images

Given a set of images what would be a way to rate them in order of which ones have the most complete coverage of the full colour spectrum? UPDATE I've posted a sister question which is an abstraction of one approach at "Most “thorough” distribution…
hippietrail
  • 15,848
  • 18
  • 99
  • 158
2
votes
2 answers

FFT window causing unequal amplification across frequency spectrum

I am using FFTW to create a spectrum analyzer in C++. After applying any window function to an input signal, the output amplitude suddenly seems to scale with frequency. Retangular Window Exact-Blackman Graphs are scaled logarithmically with a…
Krunklehorn
  • 23
  • 4
2
votes
1 answer

What are the differences between DFT and FFT that make FFT so fast?

I'm trying to understand FFTs, here's what I have so far: In order to find the magnitude of frequencies in a waveform, one must probe for them by multiplying the wave by the frequency they are searching for, in two different phases (sin and cos) and…
Seph Reed
  • 8,797
  • 11
  • 60
  • 125
2
votes
3 answers

Recovering time function from its single-sided spectrum + its Hermitian

I am trying to get a real wavelet, w, which is a column vector, from its single-sided Discrete Fourier Transform. According to the theory, the negative frequency side is complex-conjugate of the positive frequency side, but in implementing it in…
Turhan Tisinli
  • 21
  • 4
2
votes
1 answer

How to compute spectrum using awk or shell scripting?

I would like to compute spectrum using awk or shell scripting. I have a data, e.g., ifile.txt 1 2 3 4 1 3 2 2 3 99 Where 99 is an undefined value. Formula to compute spectrum is for k=1,2,3,4,... I was doing it in the following way. for i in…
Kay
  • 1,957
  • 2
  • 24
  • 46
2
votes
1 answer

Liftering cutoff

Is there a rule of thumb in deciding the cut-off value when performing the low time liftering process in Cepstral analysis? Or is it just trial and error analysis? I am trying to calculate the spectral envelope of the frequency response of data…
Kanmani
  • 479
  • 7
  • 21
2
votes
0 answers

Naudio spectrum always different

Ok. So either there is something I don't grasp about audio signals in general, or there is something up there. Problem: Every time audio sound is played, the spectrum displayed (in demo) ends differently. Try1: drum snare Try2: same…
Danielius
  • 33
  • 3
2
votes
2 answers

Plot spectrum of a wave as in Audacity

I would like to plot frequency graphs similar to the ones that Audacity can draw: I did not find a software to do that (in command line) so I started to play with python to do it, using the specgram function. As I am not able to redo such a graph…
edwin
  • 21
  • 1
  • 2
2
votes
1 answer

Plotting 2D Hilbert Spectrum in MATLAB

I want to create a 2d plot of hilbert spectrum. What i want is a time vs frequency plot, where the amplitude of the signal is represented by color changes in the plot. What i have done is this, but I need it to look like this. Thank you in…
achigeor
  • 370
  • 4
  • 12
2
votes
1 answer

Multitaper function in Python?

I'm searching a function in Python, which return the multitaper power spectral density, like pmtm for Matlab (http://fr.mathworks.com/help/signal/ref/pmtm.html) Anybody knows one ? I tried to install mtspec but without success on Python 3. Any other…
GeoffreyB
  • 536
  • 1
  • 7
  • 17
1 2 3
…
25 26