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FFT によるスペクトル解析器
Dependencies: Array_Matrix mbed SerialTxRxIntr UIT_FFT_Real DSP_ADDA
Diff: MyFFT_Analyzer/FFT_Analyzer.cpp
- Revision:
- 0:91cc5a03f0ca
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MyFFT_Analyzer/FFT_Analyzer.cpp Fri Jan 08 02:27:46 2021 +0000 @@ -0,0 +1,32 @@ +//------------------------------------------------------- +// FFT を使ってスペクトル解析を行うクラス +// +// 2020/11/07, Copyright (c) 2020 MIKAMI, Naoki +//------------------------------------------------------- + +#include "FFT_Analyzer.hpp" + +namespace Mikami +{ + FftAnalyzer::FftAnalyzer(int nFft) + : N_FFT_(nFft), fft_(nFft), wHm_(nFft, nFft), + xData_(nFft), wData_(nFft), yFft_(nFft/2+1) {} + + void FftAnalyzer::Execute(const Array<float> &xn, Array<float> &absFt) + { + xData_ = xn; // データを作業領域にコピー + + // 直流分を除去 + float sum = 0; + for (int n=0; n<N_FFT_; n++) sum = sum + xData_[n]; + float ave = sum/N_FFT_; + for (int n=0; n<N_FFT_; n++) xData_[n] = xData_[n] - ave; + + wHm_.Execute(xData_, wData_); // 窓掛け + + fft_.Execute(wData_, yFft_); // FFT の実行 + + for (int n=0; n<=N_FFT_/2; n++) // 絶対値に変換 + absFt[n] = 100.0f*abs(yFft_[n]); + } +} \ No newline at end of file