pkg load signal;

signal = csvread('unknownsignal.csv');
#Create a window for the domain we want to study
domainStart = 100;
domainEnd = 400;

lengthDomain = domainEnd - domainStart +1;
#window the signal
signal_window = zeros(size(signal));
signal_window(domainStart:domainEnd) = signal(domainStart:domainEnd) .* blackman(lengthDomain)';

#Plot the two raw signals
figure;
subplot(1,2,1);
plot(signal);
title("Signal");
xlabel("samples");
ylabel("Amplitude");

subplot(1,2,2);
plot(signal_window);
title("Blackman signal windowing");
xlabel("samples");
ylabel("Gain");

#Apply FFT to both signals.
signalFFT = fft(signal);
signalFFTwindow = fft(signal_window);
fs=600;
F = (0:length(signal)-1)*(fs/length(signal));

figure;
subplot(1,2,1);
plot(F,signalFFT);
title("Signal FFT");
xlabel("Frequency");
ylabel("Gain");

subplot(1,2,2);
plot(F,signalFFTwindow);
title("Blackman signal FFT");
xlabel("Frequency");
ylabel("Gain");


order = 50;
fc = 100;   % cutoff frequency
h_fir1 = fir1(order, fc/(fs/2));

n = 4;
Wn = fc/(fs/2);
[b, a] = butter(n, Wn);


% filter the signals
filtered_signal = filter(h_fir1, 1, signal);
filtered_windowed_signal = filter(h_fir1, 1, signal_window);
filtered_signal_butter = filter(b, a, signal);
filtered_windowed_signal_butter = filter(b, a, signal_window);

% plot the signals using subplots
t = linspace(0, length(signal)/fs, length(signal));
t_window = linspace(0, length(signal)/fs, length(signal));

subplot(2,2,1);
plot(t, signal);
title('Original Signal');

subplot(2,2,2);
plot(t_window, signal_window);
title('Windowed Signal');

subplot(2,2,3);
plot(t, filtered_signal);
title('FIR1 Filtered Signal');

subplot(2,2,4);
plot(t_window, filtered_windowed_signal);
title('FIR1 Filtered Windowed Signal');

figure;

subplot(2,2,1);
plot(t, signal);
title('Original Signal');

subplot(2,2,2);
plot(t_window, signal_window);
title('Windowed Signal');

subplot(2,2,3);
plot(t, filtered_signal_butter);
title('Butterworth Filtered Signal');

subplot(2,2,4);
plot(t_window, filtered_windowed_signal_butter);
title('Butterworth Filtered Windowed Signal');