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
Diff: SpactrumAnalysisClasses/FFT_Analysis.cpp
- Revision:
- 0:c5b026c2d07e
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/SpactrumAnalysisClasses/FFT_Analysis.cpp Sun Jul 26 02:48:23 2015 +0000 @@ -0,0 +1,51 @@ +//------------------------------------------------------- +// Class for spectrum analysis using FFT +// Copyright (c) 2014 MIKAMI, Naoki, 2014/12/30 +//------------------------------------------------------- + +#include "FFT_Analysis.hpp" + +namespace Mikami +{ + FftAnalyzer::FftAnalyzer(int nData, int nFft) + : N_DATA_(nData), N_FFT_(nFft), + hm_(nData-1, nFft), fft_(nFft) + { + pkHolder_ = new PeakHolder[nFft/2+1]; + for (int n=0; n<=nFft/2; n++) + pkHolder_[n].SetCoefs(0.2f); + + xData = new float[nData]; // Data to be analyzed + xFft = new float[nFft]; // Input for FFT + yFft = new Complex[nFft/2+1]; // Output of FFT + normY = new float[nFft/2+1]; // Powerspectrum + } + + FftAnalyzer::~FftAnalyzer() + { + delete[] pkHolder_; + delete[] xData; + delete[] xFft; + delete[] yFft; + delete[] normY; + } + + void FftAnalyzer::Execute(float xn[], float db[]) + { + // Differencing + for (int n=0; n<N_DATA_-1; n++) + xData[n] = xn[n+1] - xn[n]; + + hm_.Execute(xData, xFft); // Windowing and zero-padding + fft_.Execute(xFft, yFft); // Execute FFT + + // Smoothing + for (int n=0; n<=N_FFT_/2; n++) + normY[n] = pkHolder_[n].Execute(Sqr(yFft[n].real()) + + Sqr(yFft[n].imag())); + + // Translate to dB + for (int n=0; n<=N_FFT_/2; n++) + db[n] = 10.0f*log10f(normY[n]); + } +}