Diff: WindowingDesignLpfHpf/WindowingDesignLH.cpp

Revision:

6:e4b8e25573f3

Parent:

5:184a0b023f5c

Child:

7:46327dcab1bf

--- a/WindowingDesignLpfHpf/WindowingDesignLH.cpp	Sun Dec 07 11:55:00 2014 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,92 +0,0 @@
-//------------------------------------------------------------------------------
-//  Design of FIR filter of LPF and HPF using window method
-//
-//  2014/11/09, Copyright (c) 2014 MIKAMI, Naoki
-//------------------------------------------------------------------------------
-
-#include "WindowingDesignLH.hpp"
-
-namespace Mikami
-{
-    WindowingDesign::WindowingDesign(int order, float fs)
-            : FS_(fs), PI_FS_(3.1415926536f/fs)
-    {
-        order_ = order;
-        if ((order % 2) != 0)
-        {
-            fprintf(stderr, "order must be even.");
-            return;
-        }
-        hm_ = new float[order/2+1];
-        wn_ = new float[order/2+1];    
-        
-        HammWindow();
-    }
-        
-    void WindowingDesign::Design(int order, Type pb, float fc,
-                                 float hk[])
-    {       
-        if (pb == LPF) fC_ = fc;
-        if (pb == HPF) fC_ = 0.5f*FS_ - fc;
-    
-        if (order != order_)
-        {
-            order_ = order_;
-            if (hm_ != NULL) delete[] hm_;
-            hm_ = new float[order/2+1];
-            if (wn_ != NULL) delete[] wn_;
-            wn_ = new float[order/2+1];
-            HammWindow();
-        }
-
-        // Calculate coefficients for LPF
-        LpfCoefficients();
-        // If HPF, transform coefficients
-        if (pb != LPF) ToHpf();
-        
-        for (int k=0; k<=order/2; k++)
-            hk[k] = hm_[order/2-k];
-
-        // For compensation of gain
-        float sum = hk[order_/2];
-        if (pb == LPF)
-            for (int k=0; k<order_/2; k++)
-                sum = sum + 2.0f*hk[k];
-        if (pb == HPF)
-        {
-            float sign = -1.0;
-            for (int k=order_/2-1; k>=0; k--)
-            {
-                sum = sum + sign*2.0f*hk[k];
-                sign = -sign;
-            }
-        }
-        for (int k=0; k<=order_/2; k++)
-            hk[k] = hk[k]/sum;
-    }
-
-    // Calculation of coefficients for LPF
-    void WindowingDesign::LpfCoefficients()
-    {
-        float w = 2.0f*PI_FS_*fC_;
-        hm_[0] = 2.0f*fC_/FS_;
-        for (int k=1; k<=order_/2; k++)
-            hm_[k] = (sinf(k*w)/(PI_*k))*wn_[k];  
-    }
-    
-    // Transform LPF to HPF
-    void WindowingDesign::ToHpf()
-    {
-        for (int k=1; k<=order_/2; k+=2)
-            hm_[k] = -hm_[k];
-    }    
-
-    // Hamming window
-    void WindowingDesign::HammWindow()
-    {
-        float pi2OvM = 2.0f*PI_/(float)(order_ + 1);
-        for (int n=0; n<=order_/2; n++)
-            wn_[n] = 0.54f + 0.46f*cosf(pi2OvM*n);
-    }
-}
-