spectrum.h

#pragma once
 
#include "dsplib/array.h"
#include "dsplib/keywords.h"
 
namespace dsplib {
 
//Welch’s power spectral density estimate
//win: nfft size window
//nfft: number of DFT points (only 2^K support)
//type: power spectrum scaling (dencity/power)
 
//note: PSD unit is `Hz`, the `fs` is assumed to be 1.0
//todo: add min/max/mean/median average
 
struct WelchResult
{
    WelchResult(const arr_real& pxx_, const arr_real& f_)
      : pxx{pxx_}
      , f{f_} {
    }
    arr_real pxx;   
    arr_real f;     
};
 
//real spectrum (one-sided)
 
//use hamming window with winlen/2 overlaping
WelchResult welch(const arr_real& x, int winlen, SpectrumType scale = SpectrumType::Psd);
 
//use custom window with winlen/2 overlaping
WelchResult welch(const arr_real& x, const arr_real& win, SpectrumType scale = SpectrumType::Psd);
 
WelchResult welch(const arr_real& x, int winlen, int noverlap, int nfft, SpectrumType scale = SpectrumType::Psd);
 
WelchResult welch(const arr_real& x, const arr_real& win, int noverlap, int nfft,
                  SpectrumType scale = SpectrumType::Psd);
 
//complex spectrum (two-sided centered)
 
WelchResult welch(const arr_cmplx& x, int winlen, SpectrumType scale = SpectrumType::Psd);
 
WelchResult welch(const arr_cmplx& x, const arr_real& win, SpectrumType scale = SpectrumType::Psd);
 
WelchResult welch(const arr_cmplx& x, int winlen, int noverlap, int nfft, SpectrumType scale = SpectrumType::Psd);
 
WelchResult welch(const arr_cmplx& x, const arr_real& win, int noverlap, int nfft,
                  SpectrumType scale = SpectrumType::Psd);
 
//magnitude-squared coherence (real, one-sided)
arr_real mscohere(const arr_real& x, const arr_real& y, int winlen);
 
arr_real mscohere(const arr_real& x, const arr_real& y, const arr_real& win);
 
arr_real mscohere(const arr_real& x, const arr_real& y, int winlen, int noverlap, int nfft);
 
arr_real mscohere(const arr_real& x, const arr_real& y, const arr_real& win, int noverlap, int nfft);
 
}   // namespace dsplib