スペクトログラム このプログラムの説明は,CQ出版社「トランジスタ技術」の2021年10月号から開始された連載記事「STM32マイコンではじめるPC計測」の中にあります.このプログラムといっしょに使うPC側のプログラムについても同誌を参照してください.
Dependencies: Array_Matrix mbed SerialTxRxIntr DSP_ADDA UIT_FFT_Real Window
MySpectrogram/FFT_Spectrogram.cpp@0:3bf11d2ab6ad, 2021-09-09 (annotated)
- Committer:
- MikamiUitOpen
- Date:
- Thu Sep 09 08:55:42 2021 +0000
- Revision:
- 0:3bf11d2ab6ad
- Child:
- 1:d4e3f39ce206
1
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
MikamiUitOpen | 0:3bf11d2ab6ad | 1 | //------------------------------------------------------- |
MikamiUitOpen | 0:3bf11d2ab6ad | 2 | // スペクトログラムで使う FFT 解析用クラス |
MikamiUitOpen | 0:3bf11d2ab6ad | 3 | // |
MikamiUitOpen | 0:3bf11d2ab6ad | 4 | // 2021/05/24, Copyright (c) 2021 MIKAMI, Naoki |
MikamiUitOpen | 0:3bf11d2ab6ad | 5 | //------------------------------------------------------- |
MikamiUitOpen | 0:3bf11d2ab6ad | 6 | |
MikamiUitOpen | 0:3bf11d2ab6ad | 7 | #include "FFT_Spectrogram.hpp" |
MikamiUitOpen | 0:3bf11d2ab6ad | 8 | |
MikamiUitOpen | 0:3bf11d2ab6ad | 9 | namespace Mikami |
MikamiUitOpen | 0:3bf11d2ab6ad | 10 | { |
MikamiUitOpen | 0:3bf11d2ab6ad | 11 | FftSpectropgram::FftSpectropgram(int nData, int nFft) |
MikamiUitOpen | 0:3bf11d2ab6ad | 12 | : N_DATA_(nData), N_FFT_(nFft), |
MikamiUitOpen | 0:3bf11d2ab6ad | 13 | fft_(nFft), wHm_(nFft, nData-1), b1_(1.0f), |
MikamiUitOpen | 0:3bf11d2ab6ad | 14 | xData_(nFft), wData_(nFft), yFft_(nFft/2+1) {} |
MikamiUitOpen | 0:3bf11d2ab6ad | 15 | |
MikamiUitOpen | 0:3bf11d2ab6ad | 16 | void FftSpectropgram::Execute(const Array<float> &xn, Array<float> &absFt) |
MikamiUitOpen | 0:3bf11d2ab6ad | 17 | { |
MikamiUitOpen | 0:3bf11d2ab6ad | 18 | // 高域強調 |
MikamiUitOpen | 0:3bf11d2ab6ad | 19 | for (int n=0; n<N_DATA_-1; n++) |
MikamiUitOpen | 0:3bf11d2ab6ad | 20 | xData_[n] = xn[n+1] - b1_*xn[n]; |
MikamiUitOpen | 0:3bf11d2ab6ad | 21 | |
MikamiUitOpen | 0:3bf11d2ab6ad | 22 | // 直流分を除去 |
MikamiUitOpen | 0:3bf11d2ab6ad | 23 | float sum = 0; |
MikamiUitOpen | 0:3bf11d2ab6ad | 24 | for (int n=0; n<N_FFT_; n++) sum = sum + xData_[n]; |
MikamiUitOpen | 0:3bf11d2ab6ad | 25 | float ave = sum/N_FFT_; |
MikamiUitOpen | 0:3bf11d2ab6ad | 26 | for (int n=0; n<N_FFT_; n++) xData_[n] = xData_[n] - ave; |
MikamiUitOpen | 0:3bf11d2ab6ad | 27 | |
MikamiUitOpen | 0:3bf11d2ab6ad | 28 | wData_ = wHm_.Execute(xData_); // 窓掛け |
MikamiUitOpen | 0:3bf11d2ab6ad | 29 | fft_.Execute(wData_, yFft_); // FFT の実行 |
MikamiUitOpen | 0:3bf11d2ab6ad | 30 | for (int n=0; n<=N_FFT_/2; n++) // 絶対値に変換 |
MikamiUitOpen | 0:3bf11d2ab6ad | 31 | absFt[n] = 100.0f*abs(yFft_[n]); |
MikamiUitOpen | 0:3bf11d2ab6ad | 32 | } |
MikamiUitOpen | 0:3bf11d2ab6ad | 33 | } |