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@18:6630d61aeb3c, 2016-02-22 (annotated)

Committer:
MikamiUitOpen
Date:
Mon Feb 22 13:54:51 2016 +0000
Revision:
18:6630d61aeb3c
Parent:
4:99d4d5ea06a2 
19

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 4:99d4d5ea06a2 4 // 2015/12/15, 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 4:99d4d5ea06a2 13 yFft_(new Complex[nFft/2+1]), lifter_(new float[nLifter]),
MikamiUitOpen 4:99d4d5ea06a2 14 db_(new Complex[nFft/2+1]), cep_(new float[nFft]),
MikamiUitOpen 0:5c237fdcba23 15 cepLft_(new float[nFft]), cepFt_(new Complex[nFft/2+1])
MikamiUitOpen 0:5c237fdcba23 16 {
MikamiUitOpen 0:5c237fdcba23 17 // Generate lifter
MikamiUitOpen 0:5c237fdcba23 18 float pi2N = 3.1415926536f/nLifter;
MikamiUitOpen 0:5c237fdcba23 19 for (int n=0; n<nLifter; n++)
MikamiUitOpen 0:5c237fdcba23 20 lifter_[n] = 0.54f + 0.46f*cosf(pi2N*n);
MikamiUitOpen 0:5c237fdcba23 21 }
MikamiUitOpen 0:5c237fdcba23 22
MikamiUitOpen 0:5c237fdcba23 23 CepstrumAnalyzer::~CepstrumAnalyzer()
MikamiUitOpen 0:5c237fdcba23 24 {
MikamiUitOpen 0:5c237fdcba23 25 delete[] yFft_;
MikamiUitOpen 0:5c237fdcba23 26 delete[] lifter_;
MikamiUitOpen 0:5c237fdcba23 27 delete[] db_;
MikamiUitOpen 0:5c237fdcba23 28 delete[] cep_;
MikamiUitOpen 0:5c237fdcba23 29 delete[] cepLft_;
MikamiUitOpen 0:5c237fdcba23 30 delete[] cepFt_;
MikamiUitOpen 0:5c237fdcba23 31 }
MikamiUitOpen 0:5c237fdcba23 32
MikamiUitOpen 0:5c237fdcba23 33 void CepstrumAnalyzer::Analyze(const float xn[], float yn[])
MikamiUitOpen 0:5c237fdcba23 34 {
MikamiUitOpen 4:99d4d5ea06a2 35 fft_.Execute(xn, yFft_); // Execute FFT
MikamiUitOpen 0:5c237fdcba23 36
MikamiUitOpen 3:7c26b701f363 37 // Translate to dB and to complex
MikamiUitOpen 0:5c237fdcba23 38 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 3:7c26b701f363 39 db_[n] = Complex(10.0f*log10f(Norm(yFft_[n])), 0);
MikamiUitOpen 3:7c26b701f363 40
MikamiUitOpen 3:7c26b701f363 41 fft_.ExecuteIfft(db_, cep_); // To cepstrum
MikamiUitOpen 0:5c237fdcba23 42
MikamiUitOpen 0:5c237fdcba23 43 // Liftering
MikamiUitOpen 0:5c237fdcba23 44 cepLft_[0] = cep_[0];
MikamiUitOpen 0:5c237fdcba23 45 for (int n=1; n<N_LIFTER_; n++)
MikamiUitOpen 0:5c237fdcba23 46 cepLft_[n] = 2.0f*lifter_[n]*cep_[n];
MikamiUitOpen 0:5c237fdcba23 47 for (int n=N_LIFTER_; n<N_FFT_; n++)
MikamiUitOpen 0:5c237fdcba23 48 cepLft_[n] = 0.0f;
MikamiUitOpen 0:5c237fdcba23 49
MikamiUitOpen 3:7c26b701f363 50 // Smoothed spectrum
MikamiUitOpen 0:5c237fdcba23 51 fft_.Execute(cepLft_, cepFt_);
MikamiUitOpen 0:5c237fdcba23 52 for (int n=0; n<=N_FFT_/2; n++)
MikamiUitOpen 3:7c26b701f363 53 yn[n] = cepFt_[n].real();
MikamiUitOpen 0:5c237fdcba23 54 }
MikamiUitOpen 0:5c237fdcba23 55 }