% Back-prop Application: Removal of 60 Hz noise
% activation function is ?
% author: G. Dempsey, Bradley University
% date: March 27, 2000
% application for DSP/ANN class
% dsp.m (HW #15 part 3 preprocessor)

% function approximation:
% 1) sampled 24.7 Hz + 60 Hz signal (input)

% 2) Target: 24.7 Hz signal (output)

f=60;
f1=24.7;
n=0:1:200;
fs=500;
delt=1/fs;
t=n*delt;
x1=square(2*pi*f*n*delt);
x2=square(2*pi*f1*n*delt);
x=x1+x2;								% this is the input
xd=demp_delay(x,1,12);
xdtest1=demp_delay(x1,1,12);	% create test signals, 60 Hz only
xdtest2=demp_delay(x2,1,12);	% 24.7 Hz only
clf
disp('Press key to see 60 Hz interference')
pause
plot(t,x1);title('60 Hz Noise')
disp('Press key to see 24.7 and 60 Hz')
pause
plot(t,x)
title('Signal and Interference')
disp('Press key to see desired output')
pause
plot(t,x2)
title('The Desired Output, 24.7 Hz')

% build input pattern matrix
P=[x' xd']';

PT1=[x1' xdtest1']';		% test pattern 1
PT2=[x2' xdtest2']';		% test pattern 2

% define target
target=x2;
T=target;

disp('Press key to start network initialization/training')
pause

% INITIALIZE NETWORK ARCHITECTURE
%================================