%%% Script file for in-class 2
%%%
%%% Assignment:  
%%%     The following code generates a signal x containing an A and a C
%%%     that is several octaves above the A.
%%%      
%%%     x(t)=cos(2*pi*440*t)+cos(2*pi*2093.005*t)
%%%                A             C
%%%
%%%     Choose value for wc in following code so that the signal that
%%%     only the A signal is passed by the filter. wc is the cutoff
%%%     frequency of the DT filter. 
%%%
%%% 

fs=8000;				% sample frequency in Hz
n=0:3*fs;				% want 3 seconds of signal

x=cos(2*pi*440/fs*n)+cos(2*pi*2093.005/fs*n);

wc=.28*pi

[b,a]=butter(6,wc/pi);
y=filter(b,a,x);

soundsc(y,fs)