不韋 呂 / Mbed 2 deprecated F746_SpectralAnalysis_Example

Spectrum analyzer using DISCO-F746NG. Spectrum is calculated by FFT or linear prediction. The vowel data is in "vowel_data.hpp"

Dependencies:   BSP_DISCO_F746NG LCD_DISCO_F746NG TS_DISCO_F746NG UIT_FFT_Real mbed BUTTON_GROUP

SpactrumAnalysisClasses/LinearPrediction.cpp@6:f385940fbdb1, 2018-10-09 (annotated)

Committer:
MikamiUitOpen
Date:
Tue Oct 09 10:34:47 2018 +0000
Revision:
6:f385940fbdb1
Parent:
0:c35b8a23a863 
7

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:c35b8a23a863 1 //-----------------------------------------------------
MikamiUitOpen 0:c35b8a23a863 2 // Class for linear prediction
MikamiUitOpen 0:c35b8a23a863 3 // Copyright (c) 2014 MIKAMI, Naoki, 2014/12/30
MikamiUitOpen 0:c35b8a23a863 4 //-----------------------------------------------------
MikamiUitOpen 0:c35b8a23a863 5
MikamiUitOpen 0:c35b8a23a863 6 #include "LinearPrediction.hpp"
MikamiUitOpen 0:c35b8a23a863 7
MikamiUitOpen 0:c35b8a23a863 8 namespace Mikami
MikamiUitOpen 0:c35b8a23a863 9 {
MikamiUitOpen 0:c35b8a23a863 10 LinearPred::LinearPred(int nData, int order)
MikamiUitOpen 0:c35b8a23a863 11 : N_DATA_(nData), ORDER_(order)
MikamiUitOpen 0:c35b8a23a863 12 {
MikamiUitOpen 0:c35b8a23a863 13 r_ = new float[order+1]; // for auto-correlation
MikamiUitOpen 0:c35b8a23a863 14 k_ = new float[order]; // for PARCOR coefficients
MikamiUitOpen 0:c35b8a23a863 15 am_ = new float[order]; // working area
MikamiUitOpen 0:c35b8a23a863 16 }
MikamiUitOpen 0:c35b8a23a863 17
MikamiUitOpen 0:c35b8a23a863 18 LinearPred::~LinearPred()
MikamiUitOpen 0:c35b8a23a863 19 {
MikamiUitOpen 0:c35b8a23a863 20 delete[] r_;
MikamiUitOpen 0:c35b8a23a863 21 delete[] k_;
MikamiUitOpen 0:c35b8a23a863 22 delete[] am_;
MikamiUitOpen 0:c35b8a23a863 23 }
MikamiUitOpen 0:c35b8a23a863 24
MikamiUitOpen 0:c35b8a23a863 25 // Calculate linear-predictive coefficients
MikamiUitOpen 0:c35b8a23a863 26 bool LinearPred::Execute(const float x[], float a[],
MikamiUitOpen 0:c35b8a23a863 27 float &em)
MikamiUitOpen 0:c35b8a23a863 28 {
MikamiUitOpen 0:c35b8a23a863 29 AutoCorr(x);
MikamiUitOpen 0:c35b8a23a863 30 return Durbin(a, em);
MikamiUitOpen 0:c35b8a23a863 31 }
MikamiUitOpen 0:c35b8a23a863 32
MikamiUitOpen 0:c35b8a23a863 33 // Calculate auto-correlation
MikamiUitOpen 0:c35b8a23a863 34 void LinearPred::AutoCorr(const float x[])
MikamiUitOpen 0:c35b8a23a863 35 {
MikamiUitOpen 0:c35b8a23a863 36 for (int j=0; j<=ORDER_; j++)
MikamiUitOpen 0:c35b8a23a863 37 {
MikamiUitOpen 0:c35b8a23a863 38 r_[j] = 0.0;
MikamiUitOpen 0:c35b8a23a863 39 for (int n=0; n<N_DATA_-j; n++)
MikamiUitOpen 0:c35b8a23a863 40 r_[j] = r_[j] + x[n]*x[n+j];
MikamiUitOpen 0:c35b8a23a863 41 }
MikamiUitOpen 0:c35b8a23a863 42 }
MikamiUitOpen 0:c35b8a23a863 43
MikamiUitOpen 0:c35b8a23a863 44 // Levinson-Durbin algorithm
MikamiUitOpen 0:c35b8a23a863 45 bool LinearPred::Durbin(float a[], float &em)
MikamiUitOpen 0:c35b8a23a863 46 {
MikamiUitOpen 0:c35b8a23a863 47 // Initialization
MikamiUitOpen 0:c35b8a23a863 48 em = r_[0];
MikamiUitOpen 0:c35b8a23a863 49
MikamiUitOpen 0:c35b8a23a863 50 // Repeat
MikamiUitOpen 0:c35b8a23a863 51 for (int m=0; m<ORDER_; m++)
MikamiUitOpen 0:c35b8a23a863 52 {
MikamiUitOpen 0:c35b8a23a863 53 float w = r_[m+1];
MikamiUitOpen 0:c35b8a23a863 54 for (int j=0; j<=m-1; j++)
MikamiUitOpen 0:c35b8a23a863 55 w = w - r_[m-j]*a[j];
MikamiUitOpen 0:c35b8a23a863 56
MikamiUitOpen 0:c35b8a23a863 57 k_[m] = w/em;
MikamiUitOpen 0:c35b8a23a863 58 em = em*(1 - k_[m]*k_[m]);
MikamiUitOpen 0:c35b8a23a863 59
MikamiUitOpen 0:c35b8a23a863 60 if (em < 0) break; // Error for negative squared sum of residual
MikamiUitOpen 0:c35b8a23a863 61
MikamiUitOpen 0:c35b8a23a863 62 a[m] = k_[m];
MikamiUitOpen 0:c35b8a23a863 63 for (int j=0; j<=m-1; j++)
MikamiUitOpen 0:c35b8a23a863 64 am_[j] = a[j];
MikamiUitOpen 0:c35b8a23a863 65 for (int j=0; j<=m-1; j++)
MikamiUitOpen 0:c35b8a23a863 66 a[j] = am_[j] - k_[m]*am_[m-j-1];
MikamiUitOpen 0:c35b8a23a863 67 }
MikamiUitOpen 0:c35b8a23a863 68
MikamiUitOpen 0:c35b8a23a863 69 if (em < 0) return false;
MikamiUitOpen 0:c35b8a23a863 70 else return true;
MikamiUitOpen 0:c35b8a23a863 71 }
MikamiUitOpen 0:c35b8a23a863 72 }