不韋 呂 / Mbed 2 deprecated F446_Spectrogram

Realtime sound spectrogram using FFT or linear prediction. Spectrogram is displayed on the display of PC. リアルタイム･スペクトログラム．解析の手法：FFT，線形予測法．スペクトログラムは PC のディスプレー装置に表示される．PC 側のプログラム：F446_Spectrogram.

Dependencies:   Array_Matrix mbed SerialTxRxIntr F446_AD_DA UIT_FFT_Real

MySpectrogram/LinearPrediction.cpp@7:5ba884060d3b, 2019-11-24 (annotated)

Committer:
MikamiUitOpen
Date:
Sun Nov 24 11:14:01 2019 +0000
Revision:
7:5ba884060d3b
Parent:
0:a539141b9dec 
8

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:a539141b9dec 1 //-----------------------------------------------------
MikamiUitOpen 0:a539141b9dec 2 // Class for linear prediction
MikamiUitOpen 0:a539141b9dec 3 //
MikamiUitOpen 0:a539141b9dec 4 // 2017/02/11, Copyright (c) 2017 MIKAMI, Naoki
MikamiUitOpen 0:a539141b9dec 5 //-----------------------------------------------------
MikamiUitOpen 0:a539141b9dec 6
MikamiUitOpen 0:a539141b9dec 7 #include "LinearPrediction.hpp"
MikamiUitOpen 0:a539141b9dec 8
MikamiUitOpen 0:a539141b9dec 9 namespace Mikami
MikamiUitOpen 0:a539141b9dec 10 {
MikamiUitOpen 0:a539141b9dec 11 LinearPred::LinearPred(int nData, int order)
MikamiUitOpen 0:a539141b9dec 12 : N_DATA_(nData), order_(order),
MikamiUitOpen 0:a539141b9dec 13 r_(order+1), k_(order), am_(order) {}
MikamiUitOpen 0:a539141b9dec 14
MikamiUitOpen 0:a539141b9dec 15 // Calculate linear-predictive coefficients
MikamiUitOpen 0:a539141b9dec 16 bool LinearPred::Execute(const float x[], float a[],
MikamiUitOpen 0:a539141b9dec 17 float &em)
MikamiUitOpen 0:a539141b9dec 18 {
MikamiUitOpen 0:a539141b9dec 19 AutoCorr(x);
MikamiUitOpen 0:a539141b9dec 20 return Durbin(a, em);
MikamiUitOpen 0:a539141b9dec 21 }
MikamiUitOpen 0:a539141b9dec 22
MikamiUitOpen 0:a539141b9dec 23 // Calculate auto-correlation
MikamiUitOpen 0:a539141b9dec 24 void LinearPred::AutoCorr(const float x[])
MikamiUitOpen 0:a539141b9dec 25 {
MikamiUitOpen 0:a539141b9dec 26 for (int j=0; j<=order_; j++)
MikamiUitOpen 0:a539141b9dec 27 {
MikamiUitOpen 0:a539141b9dec 28 r_[j] = 0.0;
MikamiUitOpen 0:a539141b9dec 29 for (int n=0; n<N_DATA_-j; n++)
MikamiUitOpen 0:a539141b9dec 30 r_[j] = r_[j] + x[n]*x[n+j];
MikamiUitOpen 0:a539141b9dec 31 }
MikamiUitOpen 0:a539141b9dec 32 }
MikamiUitOpen 0:a539141b9dec 33
MikamiUitOpen 0:a539141b9dec 34 // Levinson-Durbin algorithm
MikamiUitOpen 0:a539141b9dec 35 bool LinearPred::Durbin(float a[], float &em)
MikamiUitOpen 0:a539141b9dec 36 {
MikamiUitOpen 0:a539141b9dec 37 // Initialization
MikamiUitOpen 0:a539141b9dec 38 em = r_[0];
MikamiUitOpen 0:a539141b9dec 39
MikamiUitOpen 0:a539141b9dec 40 // Repeat
MikamiUitOpen 0:a539141b9dec 41 for (int m=0; m<order_; m++)
MikamiUitOpen 0:a539141b9dec 42 {
MikamiUitOpen 0:a539141b9dec 43 float w = r_[m+1];
MikamiUitOpen 0:a539141b9dec 44 for (int j=0; j<=m-1; j++)
MikamiUitOpen 0:a539141b9dec 45 w = w - r_[m-j]*a[j];
MikamiUitOpen 0:a539141b9dec 46
MikamiUitOpen 0:a539141b9dec 47 k_[m] = w/em;
MikamiUitOpen 0:a539141b9dec 48 em = em*(1 - k_[m]*k_[m]);
MikamiUitOpen 0:a539141b9dec 49
MikamiUitOpen 0:a539141b9dec 50 if (em < 0) break; // Error for negative squared sum of residual
MikamiUitOpen 0:a539141b9dec 51
MikamiUitOpen 0:a539141b9dec 52 a[m] = k_[m];
MikamiUitOpen 0:a539141b9dec 53 for (int j=0; j<=m-1; j++)
MikamiUitOpen 0:a539141b9dec 54 am_[j] = a[j];
MikamiUitOpen 0:a539141b9dec 55 for (int j=0; j<=m-1; j++)
MikamiUitOpen 0:a539141b9dec 56 a[j] = am_[j] - k_[m]*am_[m-j-1];
MikamiUitOpen 0:a539141b9dec 57 }
MikamiUitOpen 0:a539141b9dec 58
MikamiUitOpen 0:a539141b9dec 59 if (em < 0) return false;
MikamiUitOpen 0:a539141b9dec 60 else return true;
MikamiUitOpen 0:a539141b9dec 61 }
MikamiUitOpen 0:a539141b9dec 62 }