function hd=ideal_bp1(Wcl,Wch,N)

%compute the ideal bandpass fiter unit pulse respondence hd(n)

%wcl: low cutoff frequency

%wch: high cutoff frequency

%N: window length

%hd: unit pulse respondence

alpha= (N-1)/2;

n=0:1:N-1;

m=n-alpha+eps;

hd=[sin(Wch*m)-sin(Wcl*m)]./(pi*m);