不韋 呂 / Mbed 2 deprecated F746_RealtimeSpectrumAnalyzer

Realtime spectrum analyzer. Using FFT, linear prediction, or cepstrum smoothing. Version using MEMS microphone and CODEC, named "F746_RealtimeSpectrumAnalyzer_MEMS_Mic" is registered. リアルタイム スペクトル解析器．解析の手法：FFT，線形予測法，ケプストラムによる平滑化の３種類．このプログラムの説明は，CQ出版社のインターフェース誌，2016年4月号に掲載．外付けのマイクまたは他の信号源等を A0 に接続する．線形予測法，ケプストラムは，スペクトル解析の対象を音声信号に想定してパラメータを設定している．MEMS マイクと CODEC を使ったバージョンを "F746_RealtimeSpectrumAnalyzer_MEMS_Mic" として登録．

Dependencies:   BSP_DISCO_F746NG BUTTON_GROUP LCD_DISCO_F746NG TS_DISCO_F746NG UIT_FFT_Real mbed

MyClasses/CepstrumAnalysis.cpp@0:5c237fdcba23, 2015-12-09 (annotated)

Committer:
MikamiUitOpen
Date:
Wed Dec 09 05:05:00 2015 +0000
Revision:
0:5c237fdcba23
Child:
2:095b360e0f54
1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:5c237fdcba23 1 //-------------------------------------------------------
MikamiUitOpen 0:5c237fdcba23 2 // Class for spectrum analysis using cepstrum
MikamiUitOpen 0:5c237fdcba23 3 //
MikamiUitOpen 0:5c237fdcba23 4 // 2015/12/09, Copyright (c) 2015 MIKAMI, Naoki
MikamiUitOpen 0:5c237fdcba23 5 //-------------------------------------------------------
MikamiUitOpen 0:5c237fdcba23 6
MikamiUitOpen 0:5c237fdcba23 7 #include "CepstrumAnalysis.hpp"
MikamiUitOpen 0:5c237fdcba23 8
MikamiUitOpen 0:5c237fdcba23 9 namespace Mikami
MikamiUitOpen 0:5c237fdcba23 10 {
MikamiUitOpen 0:5c237fdcba23 11 CepstrumAnalyzer::CepstrumAnalyzer(int nData, int nFft, int nLifter)
MikamiUitOpen 0:5c237fdcba23 12 : AnalyzerBase(nData, nFft), N_LIFTER_(nLifter),
MikamiUitOpen 0:5c237fdcba23 13 wHm_(nData-1, nFft),
MikamiUitOpen 0:5c237fdcba23 14 xFft_(new float[nFft]), yFft_(new Complex[nFft/2+1]),
MikamiUitOpen 0:5c237fdcba23 15 lifter_(new float[nLifter]), db_(new float[nFft/2+1]),
MikamiUitOpen 0:5c237fdcba23 16 cDb_(new Complex[nFft/2+1]), cep_(new float[nFft]),
MikamiUitOpen 0:5c237fdcba23 17 cepLft_(new float[nFft]), cepFt_(new Complex[nFft/2+1])
MikamiUitOpen 0:5c237fdcba23 18 {
MikamiUitOpen 0:5c237fdcba23 19 // Generate lifter
MikamiUitOpen 0:5c237fdcba23 20 float pi2N = 3.1415926536f/nLifter;
MikamiUitOpen 0:5c237fdcba23 21 for (int n=0; n<nLifter; n++)
MikamiUitOpen 0:5c237fdcba23 22 lifter_[n] = 0.54f + 0.46f*cosf(pi2N*n);
MikamiUitOpen 0:5c237fdcba23 23 }
MikamiUitOpen 0:5c237fdcba23 24
MikamiUitOpen 0:5c237fdcba23 25 CepstrumAnalyzer::~CepstrumAnalyzer()
MikamiUitOpen 0:5c237fdcba23 26 {
MikamiUitOpen 0:5c237fdcba23 27 delete[] xFft_;
MikamiUitOpen 0:5c237fdcba23 28 delete[] yFft_;
MikamiUitOpen 0:5c237fdcba23 29 delete[] lifter_;
MikamiUitOpen 0:5c237fdcba23 30 delete[] db_;
MikamiUitOpen 0:5c237fdcba23 31 delete[] cDb_;
MikamiUitOpen 0:5c237fdcba23 32 delete[] cep_;
MikamiUitOpen 0:5c237fdcba23 33 delete[] cepLft_;
MikamiUitOpen 0:5c237fdcba23 34 delete[] cepFt_;
MikamiUitOpen 0:5c237fdcba23 35 }
MikamiUitOpen 0:5c237fdcba23 36
MikamiUitOpen 0:5c237fdcba23 37 void CepstrumAnalyzer::Analyze(const float xn[], float yn[])
MikamiUitOpen 0:5c237fdcba23 38 {
MikamiUitOpen 0:5c237fdcba23 39 wHm_.Execute(xn, xFft_); // Windowing and zero-padding
MikamiUitOpen 0:5c237fdcba23 40 fft_.Execute(xFft_, yFft_); // Execute FFT
MikamiUitOpen 0:5c237fdcba23 41
MikamiUitOpen 0:5c237fdcba23 42 // Translate to dB
MikamiUitOpen 0:5c237fdcba23 43 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 0:5c237fdcba23 44 db_[n] = 10.0f*log10f(Norm(yFft_[n]));
MikamiUitOpen 0:5c237fdcba23 45
MikamiUitOpen 0:5c237fdcba23 46 // To smoothed spectrum using cepstrum
MikamiUitOpen 0:5c237fdcba23 47 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 0:5c237fdcba23 48 cDb_[n] = Complex(db_[n], 0);
MikamiUitOpen 0:5c237fdcba23 49
MikamiUitOpen 0:5c237fdcba23 50 fft_.ExecuteIfft(cDb_, cep_); // To cepstrum
MikamiUitOpen 0:5c237fdcba23 51
MikamiUitOpen 0:5c237fdcba23 52 // Liftering
MikamiUitOpen 0:5c237fdcba23 53 cepLft_[0] = cep_[0];
MikamiUitOpen 0:5c237fdcba23 54 for (int n=1; n<N_LIFTER_; n++)
MikamiUitOpen 0:5c237fdcba23 55 cepLft_[n] = 2.0f*lifter_[n]*cep_[n];
MikamiUitOpen 0:5c237fdcba23 56 for (int n=N_LIFTER_; n<N_FFT_; n++)
MikamiUitOpen 0:5c237fdcba23 57 cepLft_[n] = 0.0f;
MikamiUitOpen 0:5c237fdcba23 58
MikamiUitOpen 0:5c237fdcba23 59 fft_.Execute(cepLft_, cepFt_);
MikamiUitOpen 0:5c237fdcba23 60 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 0:5c237fdcba23 61 yn[n] = cepFt_[n].real() + 10.0f;
MikamiUitOpen 0:5c237fdcba23 62 }
MikamiUitOpen 0:5c237fdcba23 63 }