Diff: MyFFT_Analyzer/FFT_Analyzer.cpp

Revision:

0:91cc5a03f0ca

diff -r 000000000000 -r 91cc5a03f0ca MyFFT_Analyzer/FFT_Analyzer.cpp
--- /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]);
+    }
+}
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