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@3:7c26b701f363, 2015-12-14 (annotated)

Committer:
MikamiUitOpen
Date:
Mon Dec 14 13:44:42 2015 +0000
Revision:
3:7c26b701f363
Parent:
2:095b360e0f54
Child:
4:99d4d5ea06a2
4

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 3:7c26b701f363 4 // 2015/12/14, 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 3:7c26b701f363 12 : AnalyzerBase(nData, nFft, nFft), N_LIFTER_(nLifter),
MikamiUitOpen 0:5c237fdcba23 13 xFft_(new float[nFft]), yFft_(new Complex[nFft/2+1]),
MikamiUitOpen 3:7c26b701f363 14 lifter_(new float[nLifter]), db_(new Complex[nFft/2+1]),
MikamiUitOpen 3:7c26b701f363 15 cep_(new float[nFft]),
MikamiUitOpen 0:5c237fdcba23 16 cepLft_(new float[nFft]), cepFt_(new Complex[nFft/2+1])
MikamiUitOpen 0:5c237fdcba23 17 {
MikamiUitOpen 0:5c237fdcba23 18 // Generate lifter
MikamiUitOpen 0:5c237fdcba23 19 float pi2N = 3.1415926536f/nLifter;
MikamiUitOpen 0:5c237fdcba23 20 for (int n=0; n<nLifter; n++)
MikamiUitOpen 0:5c237fdcba23 21 lifter_[n] = 0.54f + 0.46f*cosf(pi2N*n);
MikamiUitOpen 0:5c237fdcba23 22 }
MikamiUitOpen 0:5c237fdcba23 23
MikamiUitOpen 0:5c237fdcba23 24 CepstrumAnalyzer::~CepstrumAnalyzer()
MikamiUitOpen 0:5c237fdcba23 25 {
MikamiUitOpen 0:5c237fdcba23 26 delete[] xFft_;
MikamiUitOpen 0:5c237fdcba23 27 delete[] yFft_;
MikamiUitOpen 0:5c237fdcba23 28 delete[] lifter_;
MikamiUitOpen 0:5c237fdcba23 29 delete[] db_;
MikamiUitOpen 0:5c237fdcba23 30 delete[] cep_;
MikamiUitOpen 0:5c237fdcba23 31 delete[] cepLft_;
MikamiUitOpen 0:5c237fdcba23 32 delete[] cepFt_;
MikamiUitOpen 0:5c237fdcba23 33 }
MikamiUitOpen 0:5c237fdcba23 34
MikamiUitOpen 0:5c237fdcba23 35 void CepstrumAnalyzer::Analyze(const float xn[], float yn[])
MikamiUitOpen 0:5c237fdcba23 36 {
MikamiUitOpen 0:5c237fdcba23 37 wHm_.Execute(xn, xFft_); // Windowing and zero-padding
MikamiUitOpen 0:5c237fdcba23 38 fft_.Execute(xFft_, yFft_); // Execute FFT
MikamiUitOpen 0:5c237fdcba23 39
MikamiUitOpen 3:7c26b701f363 40 // Translate to dB and to complex
MikamiUitOpen 0:5c237fdcba23 41 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 3:7c26b701f363 42 db_[n] = Complex(10.0f*log10f(Norm(yFft_[n])), 0);
MikamiUitOpen 3:7c26b701f363 43
MikamiUitOpen 3:7c26b701f363 44 fft_.ExecuteIfft(db_, cep_); // To cepstrum
MikamiUitOpen 0:5c237fdcba23 45
MikamiUitOpen 0:5c237fdcba23 46 // Liftering
MikamiUitOpen 0:5c237fdcba23 47 cepLft_[0] = cep_[0];
MikamiUitOpen 0:5c237fdcba23 48 for (int n=1; n<N_LIFTER_; n++)
MikamiUitOpen 0:5c237fdcba23 49 cepLft_[n] = 2.0f*lifter_[n]*cep_[n];
MikamiUitOpen 0:5c237fdcba23 50 for (int n=N_LIFTER_; n<N_FFT_; n++)
MikamiUitOpen 0:5c237fdcba23 51 cepLft_[n] = 0.0f;
MikamiUitOpen 0:5c237fdcba23 52
MikamiUitOpen 3:7c26b701f363 53 // Smoothed spectrum
MikamiUitOpen 0:5c237fdcba23 54 fft_.Execute(cepLft_, cepFt_);
MikamiUitOpen 0:5c237fdcba23 55 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 3:7c26b701f363 56 yn[n] = cepFt_[n].real();
MikamiUitOpen 0:5c237fdcba23 57 }
MikamiUitOpen 0:5c237fdcba23 58 }
MikamiUitOpen 2:095b360e0f54 59