Talk:Raised cosine

why does the image use an alpha = 2 when the text clearly says alpha lives in [0,1]?


 * order:   order of the filter
 * f_cut:   cut frequency of the lowpass filter
 * Rolloff: rolloff factor [0..1]
 * Fs:      sampling frequency

Matlab command firrcos( order, f_cut, Rolloff, Fs, 'rolloff' );

Matlab code equivalent % calculate taps for k=0:order / 2 temp_x( k + 1 ) = ( sinc( 2*k*Ts*f_cut ) * cos( 2*pi*Rolloff*k*Ts*f_cut ) ) / ( 1 - (2*Rolloff*k*Ts*f_cut)^2 ); end; % mirror to Y  for k=1:order+1 if( k <= order/2+1 ) index = (order/2+1) - k + 1; else index = k - order/2; end; X( k ) = temp_x( index ); end;

C++ code static float sinc( float x ) {   if ( x == 0 ) return 1.0; else return sin( PI*x ) / (PI*x); } static float pow( float x ) {   return x*x; }  static float* firrcos( int order, float f_cut, float Rolloff, int Fs ) {   float* temp_x = new float( order/2 +1 ); float* X = new float( order + 1 ); float Ts = 1.0 / Fs; // taps for (int k = 0; k <= order/2; k++) temp_x[ k ] = sinc( 2*k*Ts*f_cut ) * cos( 2*PI*Rolloff*k*Ts*f_cut ) / pow( 1 - 2*Rolloff*k*Ts*f_cut ); // mirror to Y axis for (int k = 0, index = 0; k < order+1; k++) {     if( k < order/2 + 1 ) index = order/2 -k; else index = k - order/2; X[ k ] = temp_x[ index ]; }   return X;  }

Replaced with redirect
I have replaced this article with a redirect to raised-cosine filter, as there was nothing in this article that wasn't covered in more detail in that article. Oli Filth 00:33, 26 January 2007 (UTC)