Package wellen.analysis

Class FFT

java.lang.Object
wellen.analysis.FFT
public final class FFT extends Object
Wrapper for calling a hopefully Fast Fourier transform. Makes it easy to switch FFT algorithm with minimal overhead.

  • Constructor Summary

    Constructors
    Constructor
    Description
    FFT(int size)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    backwardsTransform(float[] data)
    Computes inverse DFT.
    double
    binToHz(int binIndex, float sampleRate)
     
    void
    forwardTransform(float[] data)
    Computes forward DFT.
    void
    modulus(float[] data, float[] amplitudes)
    Calculates the the modulus for each element in data and stores the result in amplitudes.
    float
    modulus(float[] data, int index)
    Returns the modulus of the element at index bufferCount.
    void
    powerAndPhaseFromFFT(float[] data, float[] power, float[] phase)
    Returns magnitude (or power) and phase for the FFT transformed data.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • FFT

      public FFT(int size)
      Parameters:
      size - size of buffer

  • Method Details

    • forwardTransform

      public void forwardTransform(float[] data)
      Computes forward DFT.
      Parameters:
      data - data to transform.

    • backwardsTransform

      public void backwardsTransform(float[] data)
      Computes inverse DFT.
      Parameters:
      data - data to transform

    • binToHz

      public double binToHz(int binIndex, float sampleRate)
      Parameters:
      binIndex - index of the bin
      sampleRate - sample rate
      Returns:
      frequency of bin in Hz

    • modulus

      public float modulus(float[] data, int index)
      Returns the modulus of the element at index bufferCount. The modulus, magnitude or absolute value is (a²+b²) ^ 0.5 with a being the real part and b the imaginary part of a complex number.
      Parameters:
      data - The FFT transformed data.
      index - The index of the element.
      Returns:
      The modulus, magnitude or absolute value of the element at index bufferCount

    • modulus

      public void modulus(float[] data, float[] amplitudes)
      Calculates the the modulus for each element in data and stores the result in amplitudes.
      Parameters:
      data - The input data.
      amplitudes - The output modulus info or amplitude.

    • powerAndPhaseFromFFT

      public void powerAndPhaseFromFFT(float[] data, float[] power, float[] phase)
      Returns magnitude (or power) and phase for the FFT transformed data.
      Parameters:
      data - The FFT transformed data.
      power - The array where the magnitudes or powers are going to be stored. It is half the length of data (FFT size).
      phase - The array where the phases are going to be stored. It is half the length of data (FFT size).