不韋 呂 / Mbed 2 deprecated UIT2_SpectrumAnalyzer

Real-time spectrum analyzer for ST Nucleo F401RE using Seeed Studio 2.8'' TFT Touch Shield V2.0.

Dependencies:   SeeedStudioTFTv2 UITDSP_ADDA UIT_FFT_Real mbed

SpactrumAnalysisClasses/FFT_Analysis.cpp@0:c5b026c2d07e, 2015-07-26 (annotated)

Committer:
MikamiUitOpen
Date:
Sun Jul 26 02:48:23 2015 +0000
Revision:
0:c5b026c2d07e
1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:c5b026c2d07e 1 //-------------------------------------------------------
MikamiUitOpen 0:c5b026c2d07e 2 // Class for spectrum analysis using FFT
MikamiUitOpen 0:c5b026c2d07e 3 // Copyright (c) 2014 MIKAMI, Naoki, 2014/12/30
MikamiUitOpen 0:c5b026c2d07e 4 //-------------------------------------------------------
MikamiUitOpen 0:c5b026c2d07e 5
MikamiUitOpen 0:c5b026c2d07e 6 #include "FFT_Analysis.hpp"
MikamiUitOpen 0:c5b026c2d07e 7
MikamiUitOpen 0:c5b026c2d07e 8 namespace Mikami
MikamiUitOpen 0:c5b026c2d07e 9 {
MikamiUitOpen 0:c5b026c2d07e 10 FftAnalyzer::FftAnalyzer(int nData, int nFft)
MikamiUitOpen 0:c5b026c2d07e 11 : N_DATA_(nData), N_FFT_(nFft),
MikamiUitOpen 0:c5b026c2d07e 12 hm_(nData-1, nFft), fft_(nFft)
MikamiUitOpen 0:c5b026c2d07e 13 {
MikamiUitOpen 0:c5b026c2d07e 14 pkHolder_ = new PeakHolder[nFft/2+1];
MikamiUitOpen 0:c5b026c2d07e 15 for (int n=0; n<=nFft/2; n++)
MikamiUitOpen 0:c5b026c2d07e 16 pkHolder_[n].SetCoefs(0.2f);
MikamiUitOpen 0:c5b026c2d07e 17
MikamiUitOpen 0:c5b026c2d07e 18 xData = new float[nData]; // Data to be analyzed
MikamiUitOpen 0:c5b026c2d07e 19 xFft = new float[nFft]; // Input for FFT
MikamiUitOpen 0:c5b026c2d07e 20 yFft = new Complex[nFft/2+1]; // Output of FFT
MikamiUitOpen 0:c5b026c2d07e 21 normY = new float[nFft/2+1]; // Powerspectrum
MikamiUitOpen 0:c5b026c2d07e 22 }
MikamiUitOpen 0:c5b026c2d07e 23
MikamiUitOpen 0:c5b026c2d07e 24 FftAnalyzer::~FftAnalyzer()
MikamiUitOpen 0:c5b026c2d07e 25 {
MikamiUitOpen 0:c5b026c2d07e 26 delete[] pkHolder_;
MikamiUitOpen 0:c5b026c2d07e 27 delete[] xData;
MikamiUitOpen 0:c5b026c2d07e 28 delete[] xFft;
MikamiUitOpen 0:c5b026c2d07e 29 delete[] yFft;
MikamiUitOpen 0:c5b026c2d07e 30 delete[] normY;
MikamiUitOpen 0:c5b026c2d07e 31 }
MikamiUitOpen 0:c5b026c2d07e 32
MikamiUitOpen 0:c5b026c2d07e 33 void FftAnalyzer::Execute(float xn[], float db[])
MikamiUitOpen 0:c5b026c2d07e 34 {
MikamiUitOpen 0:c5b026c2d07e 35 // Differencing
MikamiUitOpen 0:c5b026c2d07e 36 for (int n=0; n<N_DATA_-1; n++)
MikamiUitOpen 0:c5b026c2d07e 37 xData[n] = xn[n+1] - xn[n];
MikamiUitOpen 0:c5b026c2d07e 38
MikamiUitOpen 0:c5b026c2d07e 39 hm_.Execute(xData, xFft); // Windowing and zero-padding
MikamiUitOpen 0:c5b026c2d07e 40 fft_.Execute(xFft, yFft); // Execute FFT
MikamiUitOpen 0:c5b026c2d07e 41
MikamiUitOpen 0:c5b026c2d07e 42 // Smoothing
MikamiUitOpen 0:c5b026c2d07e 43 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 0:c5b026c2d07e 44 normY[n] = pkHolder_[n].Execute(Sqr(yFft[n].real())
MikamiUitOpen 0:c5b026c2d07e 45 + Sqr(yFft[n].imag()));
MikamiUitOpen 0:c5b026c2d07e 46
MikamiUitOpen 0:c5b026c2d07e 47 // Translate to dB
MikamiUitOpen 0:c5b026c2d07e 48 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 0:c5b026c2d07e 49 db[n] = 10.0f*log10f(normY[n]);
MikamiUitOpen 0:c5b026c2d07e 50 }
MikamiUitOpen 0:c5b026c2d07e 51 }